37
19 Chapter Nutrition Mark Mirabelli, MD, and Ramsey Shehab, MD Key Points Foods containing carbohydrates from whole grains, fruits, vegetables, and low-fat milk are important components of and should be included in a healthy diet (strength of recommendation: A). With regard to the glycemic effects of carbohydrates, the total amount of carbohydrates in meals is more important than the source (i.e., starches or sugars) or type (i.e., GI) (strength of recommendation: B). There is no evidence to support that sodium restriction reduces morbidity or mortality in patients with hypertension, nor that modest sodium restriction is harmful (strength of recommendation: A). Diets that result in long-term weight loss of 5–7%, along with exercise of moderate intensity for at least 150 min/week (average of 30 minutes 5 times/week) have been shown to reduce the incidence of type 2 diabetes (strength of recommendation: A). Adherence to any diet with caloric restriction below the usual energy requirements will result in weight loss (strength of recommendation: B). Consumption of dietary fiber improves lipid profiles and may reduce cardiovascular morbidity and mortality (strength of recommendation: B). Consumption of omega-3 fatty acids improves lipid profiles and may reduce cardiovascular morbidity and mortality (strength of recommendation: B). For persons who consume alcohol, limiting consumption to 1–2 drinks daily may reduce mortality (strength of recommendation: B). Low-carbohydrate diets do not adversely affect and may improve lipid profiles, but evidence of their effect on long-term cardiovascular health is lacking (strength of recommendation: C). Low-fat diets can improve total cholesterol and may reduce cardiovascular risk factors (strength of recommendation: C). Low-carbohydrate diets are slightly more effective than low-fat diets for initial, short- term weight loss (3–6 months), but they are no more effective after 1 year (strength of recommendation: C). Because long-term data on patient-oriented outcomes are lacking for many diets, it is not possible to clearly endorse one diet over another (strength of recommendation: C). Introduction A healthy diet is essential to disease prevention, treatment, and perhaps longevity. Over the past few decades, mounting evidence has implicated diet not only as a cause, but also an adjunct to treatment for many chronic diseases such diabetes mellitus, stroke, cardiovascular disease, and obe- sity. These chronic diseases disproportionately affect developed countries and especially men, for whom these chronic diseases are leading causes of death. This chapter will provide a histor- ical background of governmental nutritional guidelines, an overview of general nutrition, die- tary assessment, and various guidelines that exist for low-fat, low-carbohydrate, and low-calorie options. In addition, we will examine the role of nutrition in the prevention and treatment of chronic diseases in men and conclude with evidence-based dietary recommendations to help foster change and promote healthy living. 349

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Page 1: Clinical Men's Health || Nutrition

19Chapter

NutritionMark Mirabelli, MD, and Ramsey Shehab, MD

Key Points

� Foods containing carbohydrates from wholegrains, fruits, vegetables, and low-fat milkare important components of and should beincluded in a healthy diet (strength ofrecommendation: A).

� With regard to the glycemic effects ofcarbohydrates, the total amount ofcarbohydrates in meals is more importantthan the source (i.e., starches or sugars) ortype (i.e., GI) (strength of recommendation: B).

� There is no evidence to support that sodiumrestriction reduces morbidity or mortality inpatients with hypertension, nor that modestsodium restriction is harmful (strength ofrecommendation: A).

� Diets that result in long-term weight loss of5–7%, along with exercise of moderateintensity for at least 150 min/week (averageof 30 minutes 5 times/week) have beenshown to reduce the incidence of type2 diabetes (strength of recommendation: A).

� Adherence to any diet with caloric restrictionbelow the usual energy requirements willresult in weight loss (strength ofrecommendation: B).

� Consumption of dietary fiber improves lipidprofiles and may reduce cardiovascularmorbidity and mortality (strength ofrecommendation: B).

� Consumption of omega-3 fatty acidsimproves lipid profiles and may reducecardiovascular morbidity and mortality(strength of recommendation: B).

� For persons who consume alcohol, limitingconsumption to 1–2 drinks daily may reducemortality (strength of recommendation: B).

� Low-carbohydrate diets do not adverselyaffect and may improve lipid profiles, but

evidence of their effect on long-termcardiovascular health is lacking (strength ofrecommendation: C).

� Low-fat diets can improve total cholesteroland may reduce cardiovascular risk factors(strength of recommendation: C).

� Low-carbohydrate diets are slightly moreeffective than low-fat diets for initial, short-term weight loss (3–6 months), but they areno more effective after 1 year (strength ofrecommendation: C).

� Because long-term data on patient-orientedoutcomes are lacking for many diets, it is notpossible to clearly endorse one diet overanother (strength of recommendation: C).

Introduction

A healthy diet is essential to disease prevention,treatment, and perhaps longevity. Over the pastfew decades, mounting evidence has implicateddiet not only as a cause, but also an adjunct totreatment for many chronic diseases such diabetesmellitus, stroke, cardiovascular disease, and obe-sity. These chronic diseases disproportionatelyaffect developed countries and especially men,for whom these chronic diseases are leadingcauses of death. This chapter will provide a histor-ical background of governmental nutritionalguidelines, an overview of general nutrition, die-tary assessment, and various guidelines that existfor low-fat, low-carbohydrate, and low-calorieoptions. In addition, we will examine the roleof nutrition in the prevention and treatment ofchronic diseases in men and conclude withevidence-based dietary recommendations to helpfoster change and promote healthy living.

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4Special Concerns of the Adolescent and Adult Male

Government Regulation

In the United States, Recommended DietaryAllowances (RDAs) were established by the Foodand Nutrition Board of the National Academy ofSciences in 1941 and have since been updated 10times. The first attempts at establishing dietarystandards were made in 1894, and again duringWorld War I, and were then formalized in 1933with recommendations from the US Departmentof Agriculture (USDA) on consumption of cal-cium, iron, phosphorus, vitamin A, and vitamin C.The original goal of establishing an RDA for aparticular nutrient was neither to treat or toprevent a chronic disease nor to optimize health,but rather to prevent a nutritional deficiency.RDAs constitute the levels of intake of essentialnutrients that are adequate to meet the knownneeds of almost all healthy persons. In 1953, asa way to explain the RDAs to the public, theUSDA introduced the four food groups: themeats, poultry, fish, and egg group; the dairygroup; the breads and grains group; and the fruitsand vegetables group.

In 1973, the USDA established its own set ofRDAs based on those of the Food and NutritionBoard, designed to replace the minimum dailyrequirements that had previously been used forlabeling. The final revision was established in1989 when RDAs were determined for protein, 11vitamins, and 7 minerals. These RDAs were setfor different age groups, for men and women, andfor pregnant and nursing mothers. Finally, theBoard also established Estimated Safe and Ade-quate Daily Dietary Intakes for seven other nutri-ents for which insufficient data were available toestablish a certain RDA. Also in 1989, the Foodand Nutrition Board published a comprehensivevolume, Diet and Health, which reviewed the avail-able scientific literature and was later reduced intomore usable forms for medical professionals andthe lay public.1

Despite decades of constant revision, by theearly 1990s the US RDAs were quickly becomingoutdated and inadequate for determining opti-mal nutrition. An expanding interest in nutritionby both the scientific and lay communities ledto questions on the importance of higher intakesof some nutrients to improve health, prevent ortreat disease, or even improve performance. TheRDAs were criticized for not acknowledgingindividual differences and emphasizing onlypopulation-level recommendations. Some con-sumer advocacy groups also criticized the USDAand the Food and Nutrition Board for adjustingRDAs in response to pressure from the meat

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and dairy industries. The USDA published thefirst Food Guide Pyramid in 1992 to replace thefour food groups. Finally, food fortification anddietary supplements were subject to decreasedregulation with the advent of the Dietary Supple-ment Health and Education Act of 1994.2 Thus,from 1996 through 1997, the Food and NutritionBoard developed a new, more comprehensiveapproach to setting dietary guidelines. Thecurrent RDAs were revised and replaced withDietary Reference Intakes (DRIs) to providerecommended nutrient intakes for use in a vari-ety of settings.3

Each DRI value has specific recommendationsbased on age and gender. To help balance individ-ual needs versus general recommendations,RDAs, adequate intakes (AIs), and tolerable upperintake levels are used as guidelines for individ-uals, whereas estimated average requirementsprovide guidelines for groups and populations(Table 19-1). The 1997 revisions also incorporated,for the first time, factors that might modify theseguidelines, such as bioavailability of nutrientsfrom different sources, nutrient-nutrient andnutrient-drug interactions, and intakes from foodfortifiers and supplements.

RDAs and DRIs are used as the baseline inmaking more general recommendations regard-ing which foods to consume. Recommendationsnow focus on altering dietary components toreduce the risk of disease as well as highlightingthe types and amounts of foods required to pre-vent deficiencies. Using the Food and NutritionBoard’s new DRIs as a base, these recommenda-tions are published jointly by the USDA and USDepartment of Health and Human Services asthe Dietary Guidelines for Americans and havebeen updated every 5 years since 1980, with themost recent update in 2005.4

Other governmental and public and privatenonprofit groups such as the American HeartAssociation (AHA), the American Diabetes Asso-ciation (ADA), the World Health Organization,the Institute of Medicine, the National ResearchCouncil, Physicians Committee for ResponsibleMedicine, Oldways Preservation and ExchangeTrust, and various branches within the NationalInstitutes of Health have also published guide-lines and recommendations on the role of dietin health. Private industry lobbying groups, suchas the National Dairy Council, the United FreshFruit and Vegetable Association, the Soft DrinkAssociation, the American Meat Institute, theCattlemen’s Beef Association, and the WheatFoods Council, may also promote certain foodsto the public and the government.5

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Table 19-1. US Department of Agriculture Dietary Reference Intakes

Recommended dietary

allowance (RDA)

Average daily nutrient intake level that is sufficient to meet the nutrient requirements

of nearly all persons (97–98%) in a given life stage and gender group, intended for

assessing the diets of healthy individuals, not for assessing or planning diets for

groups

Acceptable macronutrient

distribution range

Range of macronutrient intakes for a particular energy source associated with reduced

risk of chronic disease while providing adequate intakes of essential nutrients

Adequate intake Recommended average daily nutrient level based on observed or experimentally

determined estimates of average nutrient intakes by a group of healthy persons, used

when the RDA cannot be determined and may be used to plan and evaluate diets of

individuals or groups

Tolerable upper intake

level

The highest daily nutrient intake that is likely to pose no risk of toxicity for almost all

individuals in a given life stage and gender group

Estimated average

requirement

Nutrient intake value estimated to meet the requirement defined by a specific indicator

of adequacy in 50% of individuals in a given life stage and gender group and is

expressed as a daily value over time (e.g., at least 1 week), including adjustments for

bioavailability, and should not be used as an intake goal for an individual

Adapted from: Nutrition.gov. Available at http://www.nutrition.gov. Accessed August 4, 2006.

19Nutrition

Nutritional Basics

From an evolutionary standpoint, human biologyencourages and is well adapted to the consump-tion and storage of food whenever available.Humans are naturally omnivorous and haveevolutionarily driven preferences for foods thatcontain nutrients, such as salt or fat, that werehistorically scarce or good sources of energy.Although there is considerable debate on the“original” or Paleolithic diets of early man,unquestionably, social changes over the millenniahave made all types of nutrients more accessible,with a resultant impact on health. The relation-ship between diet and health is extraordinarilycomplex, which makes it difficult to define nutri-tional quality.

Clearly, nutritional quality is determined bythe nutrient composition of the diet. Nutrientsare substances in food that provide energy andcontribute to the structure and function of all bio-logic processes that are essential to life. Food isbuilt from essential and nonessential nutrientsas well as nonnutritive compounds. More than45 individual nutrients are classified as essentialto human life, meaning that they must beprovided regularly through the diet. Nonessentialnutrients can be made by the body in sufficientquantity and thus are not required to be ingested.Macronutrients include carbohydrates, lipids, andproteins and are required in relatively largeamounts (i.e., gram and kilogram quantities) bythe body as they are energy containing; althoughit contains no energy, water is also considered tobe a macronutrient. Micronutrients include vita-mins and minerals and are required in relatively

small amounts (i.e., microgram or milligramquantities). Other substances including alcoholmay also be consumed in the diet but do not fitinto any of these classes because they are notrequired by the body. Some non-nutritive sub-stances may play important roles in promotinghealth and minimizing disease. Optimal nutritionresults from the proper combination of nutrientsfrom foods.

Macronutrients

Lipids

Fats (i.e., solids at room temperature) and oils(i.e., liquids at room temperature) are the majorforms of lipids consumed in the diet. Lipids arethe most concentrated energy source at 9 kilocal-ories (Calories) per gram. The USDA suggeststhat 20–35% of the diet consist of fat. Based ona 2200-Calorie/day diet, this allows for approxi-mately 50–85 g of fat per day. No RDA or AIhas been set for lipid intake. The acceptablemacronutrient distribution range, which providesa minimum amount required for physiologicfunction, suggests 20–35 g/day for a 70-kg male.6

Lipids, which may be of either animal or plantorigin, include fatty acids, glycerides, phospholi-pids, and sterols.

Fatty acids may be saturated (containing nocarbon-carbon double bonds), monounsaturated(containing one double bond), or polyunsatu-rated (multiple double bonds). Increasing thedouble bonds lowers the melting temperature,which is why mono- and polyunsaturated fattyacids are more likely to be liquid at room

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4Special Concerns of the Adolescent and Adult Male

temperature. Common saturated fatty acidsinclude palmitic and stearic acids and are oftenfound in animal sources. Tropical oils such aspalm, palm kernel, and coconut also containsaturated fatty acids. The DRI for saturated fatssuggest an intake as low as possible because theyhave no physiologic requirement in the body.Monounsaturated fatty acids are most commonlyobtained as oleic acid, which is prevalent in olive,peanut, and canola oils. Approximately one halfof the daily fat intake should be in the form ofmonounsaturated fats.

Polyunsaturated fatty acids are named for thelocation of the first double bond in the carbonchain. The most important of these are the essen-tial fatty acids (EFAs). These include linoleic acidand arachidonic acid, which are omega-6 (n-6)fatty acids, and alpha-linolenic acid, eicosapen-taenoic acid (EPA), and docosahexaenoic acid(DHA), which are omega-3 (n-3) fatty acids. Inthe body, arachidonic acid can be made fromlinoleic acid, and EPA and DHA can be madefrom linolenic acid. Although these fatty acidscan be manufactured by the body, they are con-sidered essential because the rate at which theyare synthesized may not be sufficient to meetthe body’s needs. EFAs are needed for manyphysiologic processes, including maintaining theintegrity of the skin and the structure of cellmembranes and synthesizing prostaglandinsand leukotrienes. EPA and DHA are importantcomponents of the brain and retina. Alpha-linoleic acid is found vegetable oils, and EPA isprimarily obtained from cold-water fish oils.Linoleic acid is the primary omega-6 fatty acidin the American diet and is obtained from corn,soybean, and safflower oils. Omega-3 fatty acidsmay have a protective benefit in heart disease.7

EFAs are damaged by processing in the manu-facture of cooking oils, margarines, shortenings,partially hydrogenated vegetable oils, and trans-fatty acids, and are also damaged by sauteingand frying. The RDAs for an adult male are1.6 g/day of omega-3 fatty acids and 17 g/day(decreasing to 14 g/day for men older than 50years) of omega-6 fatty acids.6 Deficiencies offatty acids are rare in the US and include nonspe-cific dermatitis, liver abnormalities, impairedwound healing and vision.

Trans-fatty acids (also called trans-fat) arethose unsaturated fatty acids in which the hydro-gen atoms are found on opposite sides of thedouble-bond (“trans” configuration), which isopposite of the normal cis configuration usuallyfound in nature. Trans-fats are formed duringthe hydrogenation of oils, a processing technique

352

used in commercial foods by bubbling hydrogengas through liquid vegetable oils. The resultingproduct, partially hydrogenated vegetable oil,has improved storage characteristics and anincreased melting point. Diets with increasedtrans-fats have been shown to raise low-densitylipoprotein (LDL) cholesterol and decrease high-density lipoprotein (HDL) cholesterol. Recentrecommendations regarding the role of trans-fatsin the diet have called for mandatory reportingof amounts in food and suggestions for elimina-tion. The AHA 2006 Diet and Lifestyle Recom-mendations call for trans-fat to be limited to lessthan 1% of total caloric intake. The USDA DietaryGuidelines call for trans-fat to be limited to aslittle as possible.

Other types of lipids are also important in thediet. Most fatty acids in food are found as a com-ponent of glycerides; triglycerides are the mostcommon form of lipid in both food and in thebody. Phospholipids are those containing a phos-phate group, such as phosphoglycerides. Sterolsare lipids composed of multiple carbon rings;cholesterol is the most well known lipid in thisclass. Although cholesterol is essential to thebody, it is manufactured in significant quantitiesby the liver and is thus not an essential lipid.Intake of cholesterol should be as low as possible,ideally below 200 mg daily.6

Carbohydrates

Carbohydrates are energy-containing compoundscomposed of carbon, hydrogen, and oxygen thatsupply 4 Calories/g. They are classified as eithersimple carbohydrates (i.e., simple sugars) orcomplex carbohydrates (i.e., starches). Glucose isthe end product of all carbohydrate digestionand serves as the primary energy source for thebody. Glucose metabolism in healthy adults istightly regulated primarily by the endocrinepancreas, which produces both insulin andglucagon. Monosaccharides, including glucose,are the basic component of all carbohydrates.Other monosaccharides include galactose, whichis rarely found in food, and fructose, which isfound in honey, fruits, and vegetables. Disacchar-ides include maltose (found in breads), sucrose(table sugar, found in honey, cane sugar, andmaple syrup), and lactose (found in milk). Lac-tose consumption is a common cause of diarrhea,abdominal cramping, and bloating in personswho are lactase deficient, a problem which occursrarely in Northern Europeans but is more com-mon in East Asians. Complex carbohydrates aretermed polysaccharides and include glycogen inanimals and starch and fiber in plants. Plant

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19Nutrition

starch is found as either amylose, which consistsof long chains of glucose, or amylopectin, whichconsists of branched chains of glucose. The RDAfor carbohydrates for adult men is 130 g/day.Added sugars should be limited to no more than25% of total caloric intake.6

Although simple and complex carbohydrateshave different biochemical properties, their phys-iologic action in the body may or may not signif-icantly differ. A recent and increasingly popularmethod of understanding how carbohydrateswork in the body is a rating scale called the glyce-mic index (GI) (Figure 19-1). This scale is a relativeranking of a carbohydrate’s ability to raiseplasma glucose on a scale from 0 to 100, withlow-glycemic foods rated below 55 and thoserated over 70 considered to have a high GI.8 GIis not an unalterable and intrinsic property of afood, like fat or vitamin content, but rather it is arelative property in comparison to other foods. Itis determined by feeding 50 g of the food to 10healthy people after an overnight fast. Finger-stickblood glucose samples are taken at 15–30-minuteintervals over the next 2 hours. These blood sam-ples are then averaged and used to constructa blood sugar response curve for the 2-hour period.The area under the curve (AUC) is calculated toreflect the total rise in blood glucose levels afterthe test food is eaten. The GI rating (%) is calcu-lated by dividing the AUC for the test food bythe AUC for the reference food (50 g of glucose)and multiplying by 100.8 Foods with a high GIare rapidly digested and absorbed and result ina rapid increase in plasma glucose. High-GI foodsinclude maltose, glucose, dextrose, white breadsand rice, and pancakes and muffins. Waterme-lons, bananas, pineapple, raisins, corn, potatoes,carrots, and turnips are also high-GI foods. Low-GI foods have a slower rate of rise in plasma

8

6

40 0.5 1 1.5 2 2.5

Time (hours)

Glycemic Response in Healthy Adults

High glucose response (high Gl)

Low glucose response (low Gl)

3

Pla

sma

gluc

ose

(mm

ol/l)

Figure 19-1. Glycemic response in health adults. GI, Gly-cemic index. (Adapted from: Home of the glycemic index.University of Sydney. Available at: http://www.glycemicindex.com. Accessed August 4, 2006.)

glucose and a smaller related increase in insulin.These include most fruits, vegetables, andwhole-grain products. Pasta, due to the presenceof gluten, is a low- to intermediate-GI food. Darkchocolate (over 60% cocoa) is also a low-GI food.

The term glycemic load builds on this concept.A GI value describes how quickly a carbohydrateincreases serum glucose but does not describe theamount of carbohydrate in a particular food. Theglycemic load is the GI divided by 100, multipliedby its available carbohydrate content (i.e., carbohy-drates minus fiber) in grams.9 A glycemic load of20 or more is high, a glycemic load of 11–19 ismedium, and a glycemic load of 10 or less is low.Foods that have a low glycemic load almostalways have a low GI. Foods with an intermediateor high glycemic load range from very low to veryhigh GI. High-GI foods, however, may be usefulfor quickly restoring glycogen stores after exercise.Low-GI carbohydrates form the basis of many ofthe low-carbohydrate diets.10 Diets with low-GIfoods and low overall glycemic load may resultin weight loss, improvement in serum lipid levels,and improved insulin sensitivity.11 A standard ref-erence for GI was published as the InternationalTables of Glycemic Index by The American Journalof Clinical Nutrition in 1995 and 2002.8,12

Although the GI and glycemic load are usefulpieces of information, they have several limita-tions. First, these numbers are not readily obtain-able by consumers. Second, a food’s GI isinfluenced greatly by processing, storage, andpreparation. Third, the GI for a food is specificfor only that food consumed individually, whichis not how most people eat. Others foods andbeverages consumed at the same time affect GI.Finally, the GI may confuse consumers intobelieving that all high-GI foods are unhealthy(including watermelons, corn, carrots, and bakedpotatoes) and all low-GI foods are good (includ-ing french fries), which is not necessarily the case.

Protein

Proteins are the most complex and diverse groupof macronutrients in the diet. They are organic,nitrogen-containing compounds composed ofamino acids. Protein is obtained from both ani-mal sources and plant sources. Animal sourcesare considered to be complete because they pro-vide all essential amino acids in the proper pro-portions for human use. Plant sources areincomplete protein sources because they individ-ually cannot provide all essential amino acids.There are 20 amino acids that form the buildingblocks of all proteins in the diet; 9 of these areessential, and 11 are nonessential and are formed

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4Special Concerns of the Adolescent and Adult Male

from the transamination of other amino acids.The essential amino acids include the threebranched-chain amino acids valine, isoleucine,and leucine, as well as lysine, methionine, phe-nylalanine, threonine, tryptophan, and histidine.Alanine, arginine, asparagine, aspartic acid, cys-teine, tyrosine, glutamic acid, glutamine, glycine,proline, and serine are nonessential.

Protein provides structure for the body, regu-lates metabolism, and provides energy. Throughthe digestive process, protein is denatured andabsorbed in the small intestine as tripeptidesand smaller structures, which are eventuallycompletely degraded into their constituent aminoacids. This digestive process is imperfect andoccasionally results in disease. Food allergies arecaused by abnormal foreign body immune re-sponse to normal proteins in the intestinal tract.Gluten sensitivity, or celiac disease, is an enterop-athy resulting in intestinal inflammation from areaction to gluten protein, which is found inwheat, oats, barley, and rye.

Like carbohydrates, protein contains 4 Cal-ories/g. Protein beyond that required by the dietis used for energy or converted into fat or carbo-hydrate stores. The RDA for protein in adultmales is 0.8 g/kg, or 56 g/day in an average-sized(70-kg) male.6 A severe infection may increaseprotein needs by one third. Burns increase proteinrequirements by two- to four-fold. Endurance ath-letes and other athletes who are actively buildingmuscle mass may require a higher amount ofprotein, in the range of 1.0–1.5 g of protein perkilogram of body weight.6

The amount of protein required by the bodydepends greatly on the current nitrogen balance.If more nitrogen is lost than is ingested, the bodyis in a negative nitrogen balance and intakeshould be increased. This occurs when stress isapplied to the body—such as when burns, infec-tion, or trauma occur—without a compensatoryincrease in the protein intake. A positive nitrogenbalance occurs when less nitrogen is lost thaningested. This could occur during times ofwound healing, muscle building, or growth. If anegative nitrogen balance is experienced longenough, disease will arise. Kwashiorkor is a rareyet severe type of protein-energy malnutritionthat occurs with extremely low protein intake.Typically thought of as a disease of children indeveloping countries, kwashiorkor may alsooccur in hospitalized and chronically ill adultmen. Marasmus is another severe type of pro-tein-energy malnutrition in which massivechronic caloric deficits results in ketosis andeventual muscle wasting. This occurs during

354

starvation that may be seen during famine andcertain types of eating disorders. Protein andenergy supplementation in the form of commer-cial shakes, such as Boost or Ensure, may have abeneficial effect on weight gain and mortalitybut lack evidence for improvement in clinicaloutcome, functional benefit, or reduction inlength of hospitalization according to a reviewof 49 trials covering 4970 patients conducted bythe Cochrane Database.13

Water

Water is essential for survival. The average adultmale can survive only a few days without fluidintake. Approximately 60% of body mass in anadult male is composed of water, approximatelytwo thirds of which is blood, interstitial fluid,and other extracellular fluids. Water serves as auniversal solvent in the body, maintains homeo-stasis, and allows for transport of nutrients to cellsand removal and excretion of waste products ofmetabolism. Water balance is tightly regulatedby the body through interactions of the pituitary-renal axis via arginine vasopressin (antidiuretichormone). Typical water loss for an adult male is2 liters of urine per day, 200 mL of water lost infeces, and 1.5 liters are excreted in insensiblelosses. The AI for adult males is thus approxi-mately 3.7 liters of water per day obtainedthrough both food and beverage.14 There is noupper limit listed for water because water intoxi-cation is extremely rare in healthy adults.

Micronutrients

Vitamins

Vitamins are essential nutrients. An organic com-pound is classified as a vitamin if a lack of thecompound in the diet results in symptoms thatare then relieved by addition of the substanceback into the diet. Vitamins promote and regulatea variety of chemical reactions in the body, act ascoenzymes, and are necessary for many physio-logic processes. Vitamins are named alphabeti-cally in the order they were discovered. Somesubstances originally classified as vitamins werelater found to be nonessential and were thusdropped, resulting in gaps in the list. Others,such as the B vitamin series, were once thoughtto be one compound but later found to be manydifferent substances and were thus numbered.There are 13 recognized vitamins that are classi-fied as either water soluble or fat soluble. Severalvitamin-like compounds, including choline, car-nitine, taurine, inositol, ubiquinone (coenzyme

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19Nutrition

Q 10), and lipoic acid, serve essential physiologicfunctions but are not known to be required in thediet because they are synthesized in the bodyin adequate amounts. Although choline is nota vitamin, the Food and Nutrition Board estab-lished an AI of 550 mg/day with a upper limitof 3.5 g daily.15

Water-Soluble Vitamins. The water-soluble vita-mins include the entire B complex series andvitamin C.

Thiamine, also called vitamin B1 or aneurine,acts as a coenzyme in the metabolism of carbohy-drates and branched-chain amino acids. Goodsources of thiamine include enriched or fortifiedbakery products and cereals, whole grains, nuts,legumes, seeds, and pork. Deficiency results indepression, weakness, and eventual loss ofcoordination (Wernicke’s encephalopathy) andparesthesias that constitute “dry” beriberi.Advanced or “wet” beriberi results from heartfailure and weakening of the capillary walls andsubsequent edema. Persons with alcoholism areparticularly susceptible to thiamine deficiencybecause of increased need for the vitamin withalcohol metabolism and decreased absorptionand intake. There is no known toxicity for thia-mine. The RDA in adult males for thiamine is1.2 mg/day with no upper limit.15

Riboflavin, vitamin B2, forms the coenzymesflavin mononucleotide and flavin adenine dinu-cleotide, which work in the citric acid cycle andin the breakdown of fatty acids. These coenzymesalso are active in the electron transport chain.Good sources of riboflavin include milk and otherdairy products, red meat, fish, poultry, asparagus,broccoli, and mushrooms. Ariboflavinosis resultsfrom a sustained deficiency over a period ofmonths and consists of conjunctivitis, glossitis,and dermatitis. There is no known toxicity forriboflavin, although high intakes will result inbrightly yellow urine. The RDA in adult malesfor riboflavin is 1.3 mg/day with no upper limit.15

Niacin, vitamin B3, acts as a coenzyme in avariety of reduction-oxidation reactions. Twoforms, nicotinic acid and nicotinamide, areobtained from the diet. Either form can be con-verted into nicotinamide adenine dinucleotideand nicotinamide adenine dinucleotide phos-phate. These coenzymes act in glycolysis, thecitric acid cycle, and the electron transport chain.Good sources of niacin include meat, fish, wholegrains, asparagus, peanuts, and mushrooms. Nia-cin can be synthesized in the body from trypto-phan. Deficiency results in pellagra (“rawskin”), a disease consisting of dermatitis and

diarrhea with eventual progression to dementiaand death (i.e., “the four Ds”). There is no knowntoxicity for niacin, although high intakes maycause flushing and elevation in liver enzymelevels. Niacin is indicated in high doses (1–2 gdaily) as a pharmacologic agent in hypercholes-terolemia and mixed dyslipidemia. The RDA inadult males for niacin is 35 mg/day with noupper limit.15

Vitamin B6, or pyridoxine, is actually a groupof closely related compounds that are convertedinto a coenzyme, pyridoxal phosphate. Six com-pounds, pyridoxamine, pyridoxine, pyridoxal,and three 50-phosphates (PLP, PMP, PNP) arecommonly consumed in the diet. Vitamin B6 actsas a coenzyme in the metabolism of glycogen,amino acids, and sphingoid bases. Good sourcesinclude chicken, fish, pork, liver, whole grains,brown rice, soybean, peanuts, walnuts, eggs,yeast, bananas, broccoli, and spinach. VitaminB6 is lost quickly with processing during foodpreparation. Vitamin B6 supplementation hasnot been helpful for the relief of carpal tunnelsyndrome.16,17 Results of the Norwegian VitaminTrial18 found that vitamin B6 and folate mayworsen cardiovascular disease outcome whenused to treat elevated homocysteine levels. Vita-min B6 supplementation did not improve short-term mood or cognitive functions in a trial of 76elderly men.19 Deficiency results in depression,headaches, confusion, and possible seizures.Important nutrient-drug interactions includehydralazine and isoniazid, which both interferewith metabolism of the vitamin. Sensory neurop-athy may result from toxic overdose. The RDA inadult males for pyridoxine is 1.3 mg/day foradult men younger than 50 years and 1.7 mg formen aged 50 years and older, with an upper limitof 100 mg daily.15

Vitamin B12, also called cobalamin or cyanoco-balamin, is group of cobalt-containing coen-zymes. Vitamin B12 is synthesized by bacteria,fungi, and algae and accumulates in animals.Good sources include beef and poultry. Algaeand fermented soy products such as miso andtempeh are some of the few available plant-basedsources. Absorption of vitamin B12 requires thepresence of intrinsic factor, a protein secreted byparietal cells in the stomach. The presence of gas-tric acid, pancreatic bicarbonate, and trypsin isalso required. As such, alcoholics, elderly per-sons, patients with pancreatic insufficiency,patients taking acid-blocking medications, andthose who have undergone gastrectomy or otherradical gastric surgery are at high risk for folatedeficiency. Because plant sources are very poor

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in vitamin B12, vegetarians may be at risk fordeveloping deficiency. Deficiency of folate resultsin pernicious anemia, characterized by macro-cytic anemia and severe irreversible peripheraland central neuropathy. Although vitamin B12

has a clear role in treatment of pernicious anemia,supplementation in the well-known vitamin B12

injections for undifferentiated fatigue have noestablished benefit. A Cochrane Database ofSystematic Reviews20 found insufficient evidenceto support the efficacy of vitamin B12 in improv-ing cognitive function in patients with dementiaand low serum vitamin B12 levels. There is noknown toxicity for vitamin B12. The RDA in adultmales for vitamin B12 is 2.4 mg/day with noupper limit.15

Folate or folic acid are general terms for a groupof closely related B-complex vitamins includingfolacin and pteroylpolyglutamates. They serveas coenzymes in nucleic acid production andmetabolism of amino acids. Good sources offolate include liver, yeast, spinach, and legumes.Folate is naturally unstable and easily degradedduring food preparation. Persons with alcohol-ism are at high risk for folate deficiency. Defi-ciency of folate results in megaloblastic ormacrocytic anemia. Caution should be exercisedwhen supplementing folate empirically for mac-rocytic anemia because replacement may maskvitamin B12 deficiency. Folate supplementationis also used to prevent neural tube defects inpregnancy. There is no known toxicity for folate.The RDA in adult males for folate is 400 mg/daywith a 1000-mg upper limit.15

Biotin is another B-complex vitamin that servesas a coenzyme in carboxylation reactions. Goodsources of biotin include egg yolks, soy, cereal,and yeast. Foods containing raw egg whites con-tain a protein called avidin that binds with biotin,interfering with its absorption. Deficiency isuncommon but may be seen in persons who fre-quently consume raw egg whites and those withdifferent types of malabsorption syndromes.Symptoms of deficiency include nausea, loss ofhair and change in hair color, depression, and par-esthesias. There is no known toxicity level forbiotin. Although no RDA exists, the AI in adultmales for biotin is 30 mg/daywith no upper limit.15

Pantothenic acid is a part of coenzyme A,involved in the metabolism of protein, carbohy-drates, and fat. It is also involved in cholesteroland fatty acid synthesis. Good sources of pan-tothenic acid include meat, eggs, whole grains,legumes, egg yolks, tomatoes, and broccoli. Defi-ciency is uncommon. There is no known toxicitylevel for pantothenic acid. Although no RDA

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exists, the AI in adult males for pantothenic acidis 5 mg/day with no upper limit.15

Vitamin C, or ascorbic acid, serves manypurposes. It acts as an electron donor in hydrox-ylation reactions, serving as a cofactor forreactions requiring reduced copper or iron metal-loenzymes, and it also acts as an antioxidant.Vitamin C regenerates the antioxidant propertiesof vitamin E and improves intestinal absorptionof iron. Vitamin C plays a crucial role in the for-mation of collagen. Good sources of vitamin Cinclude citrus fruits, berries, melons, and mem-bers of the cabbage family. Scurvy results fromdeficiency, with symptoms of poor wound heal-ing, gingival bleeding, bone and joint pains, andhemorrhage. Toxicity results in nausea, diarrhea,and abdominal cramps. Kidney stones, acid-baseimbalances, and destruction of vitamin B12 mayalso occur. Vitamin C supplementation is com-monly used to prevent and treat upper respira-tory viruses, although research has beenequivocal. Vitamin C is also used at dosages of1 g/day for 3 weeks before competition for ath-letes, but no conclusive evidence of improvedperformance has been noted. The RDA in adultmales for vitamin C is 90 mg/day with a 2000-mg upper limit; persons who smoke require anadditional 35 mg of vitamin C daily.21

Fat-soluble Vitamins. The fat-soluble vitaminsare A, D, E, and K.

Vitamin A comes in the forms of retinoids orcarotenoids. Retinoids include retinal, retinol,and retinoic acid and are used in vision, growth,reproduction, and maintenance of epithelial tis-sue. Liver, eggs, and dairy products are particu-larly good sources of retinoids. At least 50provitamin carotenoids can be converted intovitamin A, with beta-carotene as the most potent.These yellow, orange, and red pigments arefound in carrots, squash, apricots, peppers, andgreen leafy vegetables. Vitamin A is also obtainedthrough the use of retinoid-containing skin pro-ducts. Deficiency of vitamin A may result innight blindness, xerophthalmia, and impairedimmunity. Although vitamin A acts as an antiox-idant, no protective role has clearly been estab-lished in preventing cancer and other diseasesor slowing the aging process. Vitamin A is toxicin acute or chronic overdose and may causehypercarotenemia, in which carotenoids depos-ited in body fat cause the skin to appear yellow.Toxic levels of vitamin A may worsen or predis-pose men to osteoporosis. The RDA in adultmales for vitamin A is 900 mg with an upper limitof 3000 mg/day.22

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Vitamin D, or calciferol, is in many aspects asmuch a hormone as a vitamin. It is produced inthe skin from exposure to sunlight and has multi-ple effects on other organs. It is considered a vita-min because it becomes essential in the diet forpersons who have limited sun exposure. Goodsources of vitamin D include liver, fish, and forti-fied dairy products. Vitamin D exists in twoforms: ergocalciferol (D2) from plant sourcesand cholecalciferol (D3) from animal sources.Both types are inactive until they are convertedinto 25-hydroxy vitamin D in the liver and then1,25-dihydroxy vitamin D in the kidney. VitaminD acts in the body to regulate calcium and phos-phorus metabolism through interaction withparathyroid hormone and calcitonin. Deficiencyresults in rickets in children and osteomalacia inadults. Vitamin D may be more important thancalcium in maintaining bone health.23 Vitamin Dis more likely to be deficient in homeboundelderly persons and patients with end-stage kid-ney disease. Vitamin D is toxic in low levels ofoverdose, resulting in hypercalcemia. Althoughno RDA exists, the AI in males 19–50 years oldfor vitamin D is 5 mg, increasing to 10 mg dailyin men aged 51–70 years and 15 mg daily formen older than 70 years, with an upper limit of50 mg/day.24 Vitamin D intake is also oftenexpressed in international units (IU), where40 IU equals 1 mg.

Vitamin E, or tocopherol, exists in several dif-ferent forms. Alpha-tocopherol is the most com-mon and most potent form. Good sources ofvitamin E include plant oils, grains, nuts, andleafy green vegetables. The exact physiologicfunction of vitamin E has not been establishedbut it is thought to function as an antioxidant.No conclusive studies have linked vitamin E withdecreased rates of cancer or established it as aneffective treatment for heart disease. Vitamin Ehas recently been included in a mixture of antiox-idants that convincingly slowed the progressionof age-related macular degeneration in the Age-Related Eye Disease Study.25 Vitamin E defi-ciency is rare but may result in intravascularhemolysis and subsequent anemia; toxicity islikewise uncommon. Vitamin E interferes withvitamin K absorption and, therefore, supplemen-tation should be cautioned for persons takingCoumadin (warfarin). The RDA in adult malesfor vitamin E is 15 mg with an upper limit of1000 mg/day.21

Vitamin K, like all fat-soluble vitamins, existsin multiple forms: phylloquinone from plantsand menaquinone from animals and intestinalmicroflora. Good sources of vitamin K include

dark green, leafy vegetables, vegetable oils, andliver. Vitamin K is also obtained from productionby intestinal microflora. Vitamin K is used in theproduction of prothrombin and other clottingfactors. Vitamin K also interacts with vitamin Din bone metabolism. Deficiency of vitamin Kresults in uncontrolled hemorrhage. This fact isused by blood-thinning medications derivedfrom coumarol and dicumarol, including Couma-din. Therefore, although patients taking warfarinshould not be discouraged from eating dark,leafy vegetables and taking multivitamins con-taining vitamin K, caution and frequent monitor-ing is suggested if these are suddenly introducedor removed from the diet. Although no RDAexists, the AI in adult males is 120 mg daily withno determination on an upper limit.22

Minerals

Minerals are nonorganic elements that are essen-tial for a wide array of biologic processes. Theymay be grouped as either major or trace minerals.Major minerals are required in amounts of100 mg or more per day or are present in thebody in greater than 0.01% of body weight andinclude four cations (i.e., sodium, potassium,magnesium, calcium) and three anions (i.e., phos-phorus, chloride, and sulfur). Bicarbonate alsoserves as a major anion but is not considered amicronutrient.

Major Minerals. Sodium is the major electrolyte inblood and therefore a principal regulator of fluidvolume in the body and a key factor in nervetransmission. It is obtained from a wide varietyof dietary sources, as most processed foodscontain added sodium chloride. Even softeneddrinking water may contain a significant amountof sodium. Serum sodium is tightly regulated bythe renin-angiotensin system. Because the typicalAmerican diet is high in sodium, chronic defi-ciency is extremely rare. However, acute hypona-tremia may occur in endurance and high-performance athletes who lose more sodium thanthey replace. Acute hyponatremia may presentwith muscle cramps and nausea and progress toconfusion and coma. Persons with salt-sensitivehypertension (approximately half of those withprimary hypertension) should be counseled tofollow a low-sodium diet, which is discussedlater in this chapter. Typical American dietaryintake in men is approximately 4 g of sodiumdaily, which is above the recommended upperlimit. Despite this, no toxic effects from highsodium intake are usually observed. A CochraneDatabase review found that a low-salt diet in

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normotensive persons had a statistically signifi-cant but clinically insignificant effect on bloodpressure but was helpful in short-term reductionof blood pressure in white persons with elevatedblood pressure.26 Although no RDA exists, the AIin adult males is 1.5 g/day in men aged 18–50years, 1.3 g in men aged 50–70 years, and 1.2 gin men older than 70 years with an upper limitof 2.3 g.14

Potassium is another major electrolyte, servingas a major intracellular ion and functioning innerve transmission. Like sodium, it is regulatedby the kidney. It is obtained from fresh fruits,vegetables, and unprocessed meats. Potassiumdeficiency is much more common than sodiumdeficiency. Persons with high-salt diets and thosetaking most types of diuretics are likely to havelower serum potassium levels. Symptoms of defi-ciency may include arrhythmia, fatigue, andmuscle cramps. Toxicity from hyperkalemia iscommon in end-stage renal failure but extremelyuncommon in patients with normal renal func-tion and may result in cardiac arrhythmias. TheAI is 4.7 g/day with no upper limit.14

Chloride serves as the opposite, negativelycharged, extracellular ion to sodium. Chloridebalance is also regulated by the kidney. Chlorideis usually obtained in the diet as salt withsodium. Deficiencies in chloride are uncommon,although hypochloremia may occur with pro-longed vomiting and with use of diuretic medica-tions. The AI in adult males is 2.3 g/day for menaged 18–50 years, decreasing to 2.0 g in men aged50–70 years and 1.8 g in men older than 70 years,with an upper limit of 3.6 g daily.14

Calcium is the most abundant mineral in thebody. Ninety-nine percent of total body calciumis bound with phosphorus in hydroxyapatite,found in bones and teeth. The remainder is foundin both intravascular and extravascular fluid,where it is involved with nerve transmission,muscular contraction, and blood clotting. Cal-cium is commonly obtained as a salt in the dietin the forms of calcium carbonate, citrate, phos-phate, gluconate, malate, and lactate. Goodsources of calcium include dairy, bony fish, andleafy green vegetables. Calcium is best absorbedin the presence of vitamin D, whereas absorptionis decreased in the presence of magnesium andiron. Calcium is tightly regulated and balancedwith phosphorus via the actions of calcitoninand parathyroid hormone, as well as vitamin Dfrom the kidney. A diet high in calcium—and inparticular, dairy foods—may increase weight lossin patients on low-calorie diets.27 However, dietshigh in calcium from dairy foods have been

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linked to increased rates of prostate cancer insome studies, including a prospective trial of2776 men.28 Calcium supplementation is alsobeing investigated in the prevention of adenoma-tous colonic polyps.29 Calcium deficiency mayresult in muscle cramps and osteoporosis. Toxic-ity may result in a predisposition to nephrolithia-sis, constipation, and inhibition of absorption ofother minerals. The AI in adult males is 1 g/dayfor men aged 18–50 years, increasing to 1200 mgin men older than 50 years with an upper limitof 2.5 g daily.24

Phosphorus is bound to calcium in bones andteeth. In addition, it exists in both intravascularand extravascular fluid, where it acts as a buffer,is a major constituent of nucleic acids, and isinvolved intimately in energy production as aden-osine diphosphate and triphosphate. Goodsources of phosphorus include meat, dairy, cer-eals, and other baked goods. Deficiency is uncom-mon but may result in weakness, bone loss, andlack of appetite; toxicitymay result in bone resorp-tion. The RDA in adult males is 700 mg/day withan upper limit of 4 g daily decreasing to 3 g dailyfor men older than 70 years.24

Magnesium is involved in energy productionand nerve and muscle function. It is involved innumerous enzymatic reactions including glycoly-sis, fat oxidation, protein synthesis, and adeno-sine triphosphate synthesis. The majority ofmagnesium in the body is in bone, with 40%found in muscle and soft tissue. A small amountis in extracellular and intravascular fluid. Con-centration of magnesium is regulated by thekidney. Good sources of magnesium from thediet include nuts, leafy green vegetables, andwhole grains. Magnesium absorption is enhancedby vitamin D. Although magnesium has beentouted as an ergogenic aide, no studies haveshown that magnesium supplementation canincrease performance in athletes with normaldiets. Symptoms of deficiency include nausea,vomiting, weakness, and cardiac arrhythmias.Patients with alcoholism or end-stage kidney dis-ease are at high risk for magnesium deficiency.Magnesium toxicity may result in diarrhea, nausea,and hypotension. The RDA in adult males is420 mg/day with an upper limit of 350 mg/dayof supplement beyond any amount obtained inthe diet.24

Sulfur, or sulfate, is an important componentof the essential amino acid methionine and thenonessential amino acid cysteine. It is involvedin acid–base balance. No deficiencies or toxicitiesare known. There is no RDA, AI, nor upper limitfor sulfur.14

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Trace Minerals. The trace minerals groupincludes 19 different chemical elements that serveas important nutrients to various extents in thehuman body. They include 14 known to be essen-tial: arsenic, boron, copper, chromium, fluoride,iodine, iron, manganese, molybdenum, nickel,selenium, silicon, vanadium, and zinc. Fiveothers may also play a role in health but havenot been conclusively demonstrated as essential.These include cadmium, cobalt, lead, lithium,and tin. Several of these minerals, such as arsenic,cadmium, and lead are normally toxic but aresafe in trace amounts. There are also trace miner-als that may be found in the body but have noknown biologic function. Their presence in thediet and the body likely reflects only theirconcentration in nature. This category is fairlyloose, changing from time to time, and includesbromine, mercury, tungsten, and aluminum.

Arsenic, found in organic forms from fish andgrains, is generally nontoxic. It is used in heartfunction and cell growth. Inorganic arsenic maybe fatal in toxic doses as small as 0.6 mg/kg.30

There is no RDA, AI, nor upper limit for arsenic,although arsenic needs are estimated at 12–15 mgdaily.22

Boron is involved in calcium and magnesiummetabolism. As such, it plays a role in bonehealth. Fruits, vegetables, and nuts are high inboron. There is no RDA or AI for boron, but esti-mated needs are about 0.5–3 mg daily; the upperlimit is 20 mg daily.22

Chromium is used in glucose metabolism tofacilitate insulin action and is obtained frombrewer’s yeast, nuts, whole grains, and mush-rooms. Deficiency may result in diabetes-likesymptoms. Despite claims for anabolic or ergo-genic actions, no adequate studies have shownthat chromium supplementation can increaseperformance in athletes with normal diets. TheAI in adult males is 35 mg/day for men 18–50years old and 30 mg daily for men older than 50years, with no determined upper limit.22

Copper is important in wound healing and inthe formation of ceruloplasmin. Deficiency leadsto anemia and impaired antibody formation andinflammatory responses. Toxicity, as evidencedby Wilson’s disease, may result in cirrhosis andchronic liver failure. The RDA for adult men is900 mg/day with an upper limit of 10,000 mg.22

Fluoride is present in small amounts in all soil,water, plants, and animals. The main source inthe United States is from fluoridated watersupplies. Fluoride supplementation is indicatedfor the prevention of dental caries. Fluoride isalso involved in bone health. Toxicity may result

in paradoxic fractures. The RDA for adult men is4 mg/day with an upper limit of 10 mg.24

Iodine is obtained mainly from seafood andiodized (dietary) salt. Iodine is an essential com-ponent of thyroid hormone. Deficiency results incretinism in children, characterized by failure tothrive and mental retardation. In adults, iodinedeficiency results in hypothyroidism and theformation of a goiter. Toxicity results in para-doxic goiter from hyperthyroidism. Althoughiodine supplementation clearly increases thebody’s iodine status, the Cochrane Database31

found insufficient evidence for improvements inother, more patient-oriented outcomes. TheRDA for adult men is 150 mg/day, with an upperlimit of 1.1 mg.22

Iron is quickly bound to transferrin and car-ried throughout the body, most importantly tothe bone marrow, where it is used for the produc-tion of hemoglobin. Heme iron sources such asred meat and liver are better absorbed thannon-heme sources, such as dark leafy vegetables.A low gastric pH also facilitates absorption. Theaverage adult male consumes approximately15 mg of iron per day but absorbs only about1–2 mg daily. Unlike women, men do not havea constant source iron loss beyond normalgastrointestinal and skin sloughing, whichaccounts for about 1–2 mg of iron loss daily. Alsounlike women, middle-aged men are more likelyto have iron deficiency anemia than youngermen. Iron supplements used to correct deficiencyshould be taken with vitamin C to improveabsorption. Low iron stores, as evidenced byferritin levels below 50 mg/liter, may result in awide variety of symptoms, including fatigue,paresthesias, and restless legs syndrome. Lowferritin levels, even in the absence of frank ane-mia, are an indication for supplementation. TheRDA for adult men is 8 mg/day with an upperlimit of 45 mg.22

Manganese is obtained from whole grains,cereal, and nuts. It is involved in carbohydrateand lipid metabolism. Deficiency is exceedinglyrare but may result in nonspecific dermatitisand alterations in glucose and lipid metabolism.Toxicity may result in neuropathy. The AI foradult men is 2.3 mg/day with an upper limit of11 mg.22

Molybdenum acts as a cofactor for several enzy-matic reactions. It is obtained from dairy pro-ducts, organ meats, cereals, and legumes.Deficiency is extremely rare, and toxicity maycause gout-like symptoms of arthritis. The RDAfor adult men is 45 mg/day with a upper limit of2000 mg daily.22

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Nickel is found in chocolate, nuts, legumes,and grains. Nickel acts as a cofactor in a varietyof enzymatic reactions and affects the distribu-tion and function of other nutrients includingzinc, iron, and calcium. Deficiency is uncommon,causing failure to thrive and decreased sexualfunction. There is no RDA or AI for nickel,although daily needs are estimated at 60–260 mgdaily with an upper limit of 1 mg.22

Selenium acts as an antioxidant and is found inseafood, liver, kidney, and eggs, as well as someseeds and grains. Selenium interacts with vitaminE and other antioxidants as an essential part ofglutathione peroxidase. Selenium has been stud-ied in the prevention of a variety of cancers,including prostate cancer, without definitiveresults, but considerable epidemiologic prom-ise.32 The Randomized Study of Selenium andvitamin E for the Prevention of Prostate Cancer(SELECT Trial) has enrolled more than 32,000men and should provide clarity on this topicwhen data are reported. Deficiency may resultin muscle pain, weakness, and a rare cardiaccondition called Keshan disease. Toxicity maycause fingernail changes and hair loss. The RDAfor adult men is 55 mg/day with an upper limitof 400 mg daily.21

Silicon is involved in collagen synthesis andcalcification of bone. Dietary sources includegrains and root vegetables. Deficiency is uncom-mon, causing failure of wound healing and con-nective tissue and bone abnormalities. There isno RDA, AI, nor upper limit for silicon, althoughdaily needs are estimated at 5–20 mg.22

The exact role of vanadium in health is cur-rently unclear but it is believed to be an essentialmineral; deficiency may predispose a person tobipolar disease. There is no RDA or AI for vana-dium, although daily needs are estimated at5–20 mg. The upper limit is 1.8 mg/day.22

Zinc is abundant in red meats, dairy products,seafood, and wheat germ. Zinc is omnipresent inthe body and acts as a cofactor for numerousenzymes. The signs and symptoms of zinc defi-ciency include anorexia, growth retardation,delayed sexual maturation, hypogonadism andhypospermatogenesis, alopecia, immune disor-ders, dermatitis, night blindness, impaired taste(i.e., hypogeusia), and impaired wound healing.Zinc deficiency may result from acrodermatitisenteropathica, a recessively inherited partialdefect in intestinal zinc absorption. Biochemicalsigns associated with zinc deficiency includedecreased levels of plasma zinc (<70 mg/dL),alkaline phosphatase, and plasma testosterone.Clinical assessment of mild zinc deficiency is

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difficult because many of the signs and symp-toms are nonspecific. Nonetheless, if a malnour-ished person has a borderline-low plasma zinclevel, is subsisting on a high-fiber and high-phy-tate diet (which reduces zinc absorption), andhas reduced signs and symptoms compatiblewith deficiency, empiric treatment with zinc sup-plements (15–25 mg/day) may be tried. ACochrane Database review33 found zinc supple-mentation ineffective for the treatment of legulcers. Zinc depletion may adversely affectstrength and cardiorespiratory performance indeficient athletes through decreased activity ofthe zinc-dependent enzyme, carbonic anhy-drase.34 No studies have shown that zinc supple-mentation can increase performance in athleteswith normal diets. Toxicity may result inimpaired immune function and impairment ofcopper absorption. The RDA for adult men is11 mg/day with an upper limit of 40 mg daily.22

Non-nutritive Components of Food

Alcohol

Ethyl alcohol, or ethanol, is an energy-containingcompound; 1 g of alcohol yields 7 Calories. Alco-hol is absorbed primarily in the stomach andduodenum. One 12-oz beer, a 1.5-oz 80-proofshot of liquor, and a 5-oz glass of wine each haveapproximately 15 g of alcohol. Many studieshave supported benefits from low to moderateintake of alcohol with detrimental effects occur-ring with larger amounts. Light to moderateamounts of alcohol increase insulin sensitivityand raise HDL cholesterol levels. A systematicreview of 32 studies on alcohol intake concludedthat moderate amounts of alcohol (1–3 drinks/day), when compared with no alcohol use, wasassociated with a 33–56% lower incidence ofdiabetes and a 34% lower incidence of diabetes-related coronary heart disease.35 Conversely, thestudy also noted that, compared with moderateintake, chronic ingestion of greater than 45 g/day can cause deterioration in glucose controland a 43% increase in incidence of diabetes. Mod-erate amounts of alcohol with food have no acuteeffect on blood glucose and insulin levels. Lightto moderate alcohol intake does not increaseblood pressure, but amounts greater 30–60 g/day may cause elevated blood pressure. Thesehypertensive effects from excess alcohol arereversed after abstinence. This systematic reviewand other studies suggest a J-shaped mortalitycurve for alcohol consumption, with lowestall-cause mortality at between 1 and 2 drinks

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(15–30 g) per day for an adult male.35 Of signifi-cance in nutrition, alcohol-containing beveragesgenerally contain few other nutrients, mayreduce nutrient intake by replacing more nutri-tious foods, and can decrease absorption of anumber nutrients and alter their storage, metab-olism, and excretion. Thiamine, niacin, folate,zinc, and vitamins B6, B12, A, D, and K arecommonly deficient in alcoholics.

USDA guidelines recommend moderateintake for persons who choose to drink alcohol.If male patients choose to drink alcohol, theyshould limit their intake to no more than2 drinks/day. Persons with diabetes may con-sume moderate amounts without concern ofacute effect on glycemic control, blood pressure,or triglycerides. Men with a history of alcoholabuse, liver disease, and other high-risk condi-tions should be encouraged to abstain from alco-hol completely.

Fiber

Fiber is a non–energy-containing carbohydratecompound. The consumption of dietary fiber isencouraged by all major health and dietary orga-nizations. Although small amounts of fiber maybe digested by intestinal microflora, fiber gener-ally cannot be broken down by the digestiveprocess into energy extractable products. Fiberis classified as either functional (soluble) or die-tary (insoluble). Total fiber is the sum of dietaryand functional fiber. Functional or soluble fibersdissolve or swell in water and include pectin,mucilage, psyllium, and gums. Sources are oatbran, legumes, fruit, and seaweed, which containcarrageenan. Soluble fibers can hold 20–30 timestheir weight in water. This causes the formationof more viscous chyme in the digestive tract,which slows the rate of nutrient absorption.Soluble fibers bind bile acids and interferewith enterohepatic circulation, thus sequesteringand ultimately decreasing serum cholesterol.Insoluble fibers do not dissolve in water. Theseinclude cellulose, hemicellulose, and lignin(which is technically a noncarbohydrate). Sourcesof insoluble fiber include grain brans and crucif-erous vegetables. Insoluble fibers increase thebulk of intestinal contents. This increased stoolbulk combined with increased intraluminal fluidfrom soluble fibers stimulates peristalsis andreduces transit time. Reduced transit time mayreduce the incidence of hemorrhoids anddiverticuli, as noted in the US Physician’s HealthStudy of nearly 44,000 men.36 Fiber also has abeneficial effect on cardiovascular health. Fiberintake in quantities over 50 g daily may have a

beneficial effect on glycemia, insulinemia, andlipemia. The Framingham Offspring Study37

found that the prevalence of both insulin resis-tance and the metabolic syndrome was signifi-cantly lower among persons eating the mostcereal fiber from whole grains compared withthose eating the least. Recent ADA guidelinessuggest, however, that there is no reason to rec-ommend greater amount of fiber intake in per-sons with diabetes.38 The AI for fiber in adultmales is 38 g/day, decreasing to 30 g/day inmen older than 50 years of age.6 Although largeamounts of daily fiber (>50 g daily) requirelarge amounts of water intake to ensure normalcolonic transit, there is no upper limit on safefiber intake.

Phytochemicals

This group includes a wide array of non–energy-containing and apparently nonessential chemicalcompounds found in plants. These compoundsare the current subject of multiple investigationsand may have physiologic or pharmaceuticalactions in the body because many are thought tohave antioxidant properties. Some, such as ephed-rine, are used as the basis of current and futurepharmaceuticals. Phytochemicals include carote-noids from red, yellow, and orange foods, such ascarrots, yams, and tomatoes; lycopene in tomato-based products; lutein and zeaxanthin from leafygreens, such as spinach, endive, and romaine let-tuce; and flavonoids in brightly colored fruits andvegetables, such as blueberries, cherries, andstrawberries. Two flavonoids, rutin, and hesperi-din, are referred to as vitamin P, although theyhave no recognized nutritional necessity. Phytos-terols impair intestinal absorption of cholesteroland may significantly reduce LDL levels.39 Plantsterols are now being used in commercial spreads,such as Benecol, for this purpose. Polyphenols indark chocolate have been found to improve vascu-lar function in male smokers40 and flavonols inchocolate may also have favorable cardiovasculareffects. Policosanols derived from rice are beinginvestigated as cholesterol reducers. Phytoestro-gens, such as isoflavones, may be associated witha decreased risk of lung cancer.41 In Kuopio Ischae-mic Heart Disease Risk Factor Study,42 1889 menwere prospectivelymonitored for the developmentof cardiovascular disease in relation to intake ofenterolactone, an intestinal microflora-modifiedphytochemical. Men with the highest quartileof intake had significantly lower rates of coro-nary heart disease and cardiovascular disease.Although there is no USDA recommendation on

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phytochemical intake, the current recommenda-tion for 5–9 servings of fruits and vegetables dailywould include a considerable amount and arrayof phytochemicals.

Sugar Substitutes

A variety of products are currently used in foodin place of the naturally occurring sugars suchas glucose, fructose, lactose, and sucrose (dex-trose). Sugar alcohols are chemical derivatives ofsugar that provide minimal energy. They includemannitol, sorbitol, xylitol, maltitol, and lactitol.Cyclamate was one of the earliest artificial sweet-eners, provides no energy, and is 30 timessweeter than sucrose. It was banned by the USFood and Drug Administration (FDA) in 1969because of studies that suggested an increasecancer risk in laboratory animals.43

Another early sugar substitute is saccharin(Sweet ‘n’ Low), which is about 300 times sweeterthan sucrose. Findings from animal studiesindicated that high does of saccharin could causebladder cancer; however, human studies havenot shown any link between bladder cancer riskand saccharin intake.44 In 1977 and continuingthrough today, the FDA placed a warning onthe use of saccharin while safety studies con-tinue. Aspartame (NutraSweet, Equal) containstwo amino acids: aspartic acid and phenylala-nine. It is 200 times as sweet as sucrose andcontains 4 Calories/g. Aspartame is metabolizedto several products, including the amino acidphenylalanine, which means that persons withphenylketonuria should not consume aspartame.Neotame, an aspartame derivative that is consid-ered safer for patients with phenylketonuria, wasapproved in 2002. Acesulfame potassium (Sweetand Safe, Sunett) is 200 times as sweet as sucroseand contains no energy. Sucralose (Splenda)is an increasingly popular artificial sweetenerthat is a chlorinated sucrose derivative. Nospecific cautions have been found for acesulf-ame potassium, sucralose, and Neotame. Personswith diabetes and patients trying to lose weightshould be encouraged to use sugar substituteswhen appropriate. However, artificial sweete-ners may still cause an increase in insulin afterconsumption, thus tempering some of theirusefulness for diabetics. Non-nutritive sweet-eners are safe when consumed within theacceptable daily intake (ADI) established bythe FDA.45 Each non-nutritive sweetener hasits own ADI. For example, aspartame has anADI of 50 mg/kg, which translates into approx-imately 15 cans of diet soda daily for a 60-kgmale.46

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Nutritional Assessment

The nutritional assessment is a specialized andcomprehensive evaluation of a patient’s nutri-tional status and requirements based on dataobtained from the medical history, physical exam,and laboratory values. A proper assessment is thefoundation on which further recommendations onproper diet for the prevention and treatment ofdisease can be based. These assessments are rou-tinely performed by registered dietitians andnutritionists and should also be used by physi-cians when evaluating the nutritional status ofany patient. A complete assessment proceeds inthree parts47:

1. Define the patient’s nutritional status withrespect to energy, protein, vitamin, andmineral intake.

2. Establish optimal levels of nutritionalintake for the individual patient’s needsand make dietary recommendations basedon those needs.

3. Conduct assessments in a serial fashion toassess the effects of dietary recommenda-tions on health.

A complete medical history is the first stepin the assessment.48 In the past medical his-tory and surgical history, specific inquiry ofcardiovascular disease, diabetes mellitus, gout,alcoholism, cancer, immunodeficiencies, and pul-monary, gastrointestinal, or renal diseases shouldbe made. The disease itself or medical or surgicalinterventions used to treat it may affect the nutri-tional status of the patient. In addition to stan-dard medications and allergies, the patientshould be asked whether he takes any vitamins,minerals, or supplements and whether he hasany food allergies or sensitivities, includinglactose intolerance. Certain medications, such aslaxatives, diuretics, and antacids may directlyaffect the nutritional status of a patient or, in thecase of vitamin K–containing green vegetables,may present problems of drug-nutrient interac-tions. A family history of osteoporosis, cardiovas-cular disease, diabetes, hypertension, or obesity isimportant to note. The patient’s social historyshould be evaluated for caffeine, alcohol, andtobacco use.

A complete understanding of the patient’ssocial background will improve the clinician’sability to formulate a successful dietary recom-mendation, and a specific dietary history shouldbe elicited at this time (Table 19-2)49; a daily foodlog may be helpful as well. A complete review ofsystems is useful to further elicit any other signif-icant problems a patient may have that can

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Table 19-2. Key Questions for the Dietary History

Do you have a history of “dieting”?

Do you follow a special diet? (low-salt, vegetarian, etc.)

How successful are you at following this diet?

How many meals and snacks do you eat daily?

Do you avoid any specific foods? Why?

What types of food do you frequently/infrequently eat?

Who prepares your meals? (e.g., self, spouse, restaurant,

caregiver)

How much water/soft drinks/coffee/juice/tea/alcohol do

you drink?

Describe your typical daily food and beverage intake,

including meals and snacks (i.e., usual dietary intake

history).

Describe everything you ate and drank within the past 24

hours, including the quantities consumed and methods

of preparation (i.e., 24-hour recall).

Adapted from: Morrison G, Hark L:Medical Nutrition: A Case-Based

Approach, Malden, MA, 2003, Blackwell Publishing.

19Nutrition

herald a nutritional concern. The review of sys-tems is subjective and organ system based andshould be appropriately tailored to the age andgeneral health of the patient. Gastrointestinalsymptoms such as heartburn, dyspepsia, abdom-inal bloating, gas, constipation, and diarrhea maybe particularly salient.

The physical examination provides moreobjective measurements of the nutritional statusof a patient. For example, a patient who, accord-ing to his history, has no medical problems, takesno medicines, refrains from alcohol and tobacco,and claims to eat a low-fat diet rich in fruits andvegetables yet appears morbidly obese, hyperten-sive, and is noted to have acanthosis nigricansshould immediately focus the attention of thephysician on a nutritional imbalance. Malnutri-tion may cause a myriad of physical findings inany number of organ systems, the specifics ofwhich are beyond the scope of this chapter. Themost important baseline data to be gathered dur-ing the exam are vital signs, including bloodpressure, and an accurate height and weightmeasurements. These numbers can be used tocalculate a variety of anthropometric measure-ments that better quantify the size of a patient.Ideal body weight (for men more than 5 feet tall,106 pounds þ 6 pounds � 10% for each inch over5 feet) and percent ideal body weight (current/ideal weight) are useful rules of thumb, as is theUSDA Healthy Weight for Adults table. Bodymass index (BMI; kg/m2) should be calculatedand is the standard measure used in the diagno-sis of obesity50:

� Normal BMI: 18–25� Overweight: 25–30� Obese: 30–40� Morbidly obese: >40Distribution of body fat is typically more

visceral inmales than in females, likely due to hor-monal differences, resulting in a greater abdomi-nal-to-waist ratio. Other measurements, such asestimated percent body fat by underwater weigh-ing and bioelectric impedance, triceps or abdomi-nal skin fold testing, mid-arm circumference, andmid-arm muscle circumference are not routinelyneeded. These measurements alone may not beaccurate in establishing overnourishment orundernourishment in specific types of patients,including amputees, acutely ill patients, patientswith recent trauma or burns, and athletes with sig-nificant muscle bulk. Magnetic resonance imag-ing, dual-energy x-ray absorptiometry, and otheradvanced imaging is usually unnecessary to deter-mine body fat distribution.

The final part of a complete nutritional assess-ment is laboratory analysis.49 This provides a finalpiece of objective data to support theclinician’s diagnosis. No single laboratory testcompletely measures total nutritional status in apatient; therefore, laboratory tests are best used asan extension of the history and physical examina-tion. Levels of serum electrolytes and mineralsincluding sodium, potassium, chloride, calcium,phosphorus, and magnesium are routinely asses-sed. Ameasurement of serum iron and zinc levelsmay also be useful in certain patients. Testing forother types of minerals and metals is less com-monly necessary and should be done with anappropriate index of suspicion. A fasting serumlipid panel including total cholesterol, HDL cho-lesterol, LDL cholesterol, very-low-density lipoproteins, and triglycerides serves as auseful laboratory test and should be routinely per-formed for a complete nutritional assessment.Measures of vitamin levels, including thiamine,folate, B12, and 25-OH vitamin D are useful inappropriate patients, as are measures of liver andrenal function.

Protein status should routinely be assessed viaserum blood urea nitrogen and creatinine levels,yet these levels are highly dependent on hydra-tion status and baseline renal function. Therefore,protein status can also be assessed using a varietyof markers for patients for whom reduced proteinand caloric intake is a concern. Each of thesemarkers may also be affected by not only nutri-tion and hydration, but also diseases, surgery,and impaired liver function. Serum albumin hasthe longest half-life (18–21 days) and is useful

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4Special Concerns of the Adolescent and Adult Male

for evaluating nutritional status over the pastseveral months. Significantly depressed levels ofalbumin are associated with increased morbidityand mortality. Serum transferrin has a shorterhalf-life (8–9 days) but is also affected by ironstatus, in addition to protein and caloric intake.Serum prealbumin has a short half-life (2–3 days),which makes it useful for nutritional statusassessment over the past week. Serum retinol-binding protein has the shortest half-life of com-mercially available protein markers (12 hours),which makes it the most sensitive for dailyprotein and caloric intake. Serum retinol-bindingprotein levels are also affected by vitamin Astatus.

Dietary Choices

One of the most common questions asked of phy-sicians by their patients is “What should I eat tostay healthy?” Adult American men are increas-ingly looking for an ideal diet that maintainshealth, prevents disease, and provides an abun-dance of energy while remaining enjoyable andeasy to follow. A bewildering array of choicesexist, from low-fat and low-carbohydrate diets,to low-sodium and low-calorie diets, to other dietsthat have been promoted for prevention or treat-ment of specific diseases or that focus on particu-lar types or amounts of food. A Google searchperformed in mid 2006 for “diet AND men”revealed an astonishing 70 million-plus references.

The earliest data collected on the associationof different diets and disease were from TheSeven Countries Study51 carried out from 1958to 1970. This study explored associations amongdiet, risk, and disease experience in contrastingpopulations (i.e., United States, Japan, Greece,England, Finland, Italy, and Yugoslavia). Menaged 40–59 years in 18 areas of seven countrieswere studied, and results demonstrated thatlevels of saturated fatty acids and mean serumcholesterol predict present and future populationrates of coronary heart disease. Moreover, itserved as basis for the concept of populationand dietary causes in the development of obesity,hypertension, coronary disease, and stroke.

Based upon the Seven Countries Study’sdemonstrated risk of cardiovascular disease withincreased levels of saturated fats, the focus for thelast 25 years has been on decreasing fat intake. Asa result, the average American’s fat consumptiondropped from 40% to 34% of total calories.52

Despite these data, according to the Centers forDisease Control and Prevention, between 1971and 2000 American men increased their caloric

364

intake by 7%.52 Concurrently, obesity, hyperten-sion, diabetes, and cardiovascular disease rateshave continued to increase in men.53

Low-Fat Diets

High-fat diets are associated with increasing ratesof obesity and cardiovascular disease.51 The Mul-tiple Risk Factor Intervention trial54 conductedduring the 1970s was the first trial that examinedthe role of a low-fat diet in reducing the risk ofatherosclerosis in men. More than 6000 malepatients were placed on a low-fat diet, encour-aged to exercise, and advised to quit smoking.The trial concluded that low-fat diets, whencombined with smoking cessation and exercise,could reduce the risk of heart disease in men.The Lipid Research Clinics Coronary PrimaryPrevention Trial55 was conducted in the UnitedStates from 1976 to 1983 and involved 3806men. This trial also found evidence that a dietlow in saturated fat could reduce heart disease.55

Currently, there are a variety of low-fatdietary plans that share similar principlesbut demonstrate different food choices. TheUSDA, Dietary Approaches to Stop Hypertension(DASH), Weight Watchers, Mediterranean, andvegetarian diets are established and well-studiedlow-fat diets. More recently, the Healing FoodsPyramid diet from the University of MichiganMedical School and the Healthy Eating Pyramidfrom the Harvard School of Public Health wereintroduced; these share a similar core of recom-mendations with other low-fat diets:

� More fruits, vegetables, and whole grains� Less cholesterol, saturated fats, sweets, andsalt

� Modest amount of alcohol� Smaller meals

USDA/My Pyramid

The Dietary Guidelines for Americans56 are writ-ten to “promote good dietary habits, reservehealth and reduce risk for major chronic diseases”(Table 19-3). Like all low-fat diets, the emphasisin the USDA food guide diet is on fruits, vegeta-bles, and whole grains. The Dietary Guidelinesare explained in visual form as the USDA MyPyramid, an evolution from the previous USDAFood Guide Pyramid. In 2005, the USDA foodguide pyramid was rebuilt with the food groupsbeing represented by a rainbow of colored,vertical stripes and an illustration of a personclimbing steps to emphasize the importance ofexercise (Figure 19-2). It was also individualizedfor age, gender, and activity level and simplified

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Table 19-3. Key Recommendations from the USDA Dietary Guidelines for Americans

Topic Recommendations

Adequate nutrients within

calorie needs

Consume a variety of nutrient-dense foods and beverages within and among the basic

food groups while choosing foods that limit the intake of saturated and trans-fats,

cholesterol, added sugars, salt, and alcohol.

Meet recommended intakes within energy needs by adopting a balanced eating

pattern, such as the USDA Food Guide or the DASH Eating Plan.

Persons older than 50 years of age should consume vitamin B12 in its crystalline form

(e.g., fortified foods or supplements).

Older adults, persons with dark skin, and persons exposed to insufficient ultraviolet-

band radiation (e.g., sunlight): Consume extra vitamin D from vitamin D–fortified

foods and/or supplements.

Food groups to encourage Consume a sufficient amount of fruits and vegetables while staying within energy

needs. Two cups of fruit and 2½ cups of vegetables per day are recommended for

a reference 2000-Calorie intake, with higher or lower amounts depending on the

Calorie level.

Choose a variety of fruits and vegetables each day. In particular, select from all five

vegetable subgroups (dark green, orange, legumes, starchy vegetables, and other

vegetables) several times a week.

Consume 3 or more ounce-equivalents of whole-grain products per day, with the rest of

the recommended grains coming from enriched or whole-grain products. In general,

at least half the grains should come from whole grains.

Consume 3 cups per day of fat-free or low-fat milk or equivalent milk products.

Children and adolescents: Consume whole-grain products often; at least half the grains

should be whole grains. Children aged 2–8 years should consume 2 cups of fat-free or

low-fat milk or equivalent milk products per day. Children 9 years of age and older

should consume 3 cups of fat-free or low-fat milk or equivalent milk products per day.

Fats Consume less than 10% of calories from saturated fatty acids and less than 300 mg of

cholesterol per day, and keep trans-fatty acid consumption as low as possible.

Keep total fat intake to between 20% and 35% of calories, with most fats coming from

sources of polyunsaturated and monounsaturated fatty acids such as fish, nuts, and

vegetable oils.

When selecting and preparing meat, poultry, dry beans, and milk or milk products,

make choices that are lean, low in fat, or fat free.

Limit intake of fats and oils high in saturated and/or trans-fatty acids, and choose

products low in such fats and oils.

Children and adolescents: Keep total fat intake to between 30% and 35% of Calories

for children 2–3 years of age and between 25% and 35% of calories for children and

adolescents 4–18 years of age, with most fats coming from sources of polyunsaturated

and monounsaturated fatty acids, such as fish, nuts, and vegetable oils.

Carbohydrates Choose fiber-rich fruits, vegetables, and whole grains often.

Choose and prepare foods and beverages with little added sugar or caloric sweetener,

such as amounts suggested by the USDA Food Guide and the DASH Eating Plan.

Reduce the incidence of dental caries by practicing good oral hygiene and consuming

sugar- and starch-containing foods and beverages less frequently.

Alcoholic beverages Persons who choose to drink alcoholic beverages: Do so sensibly and in moderation—

defined as the consumption of up to one drink per day for women and up to two

drinks per day for men.

Alcoholic beverages should not be consumed by some persons, including those who

cannot restrict their alcohol intake, children and adolescents, persons taking

medications that can interact with alcohol, and those with specific medical

conditions.

Alcoholic beverages should be avoided by persons engaging in activities that require

attention, skill, or coordination, such as driving or operating machinery.

Table continued on following page

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Table 19-3. Key Recommendations from the USDA Dietary Guidelines for Americans (Continued)

Topic Recommendations

Sodium and potassium Consume less than 2300 mg (approximately 1 tsp of salt) of sodium per day.

Choose and prepare foods with little salt. At the same time, consume potassium-rich

foods, such as fruits and vegetables.

Persons with hypertension, African Americans, and middle-aged and older adults: Aim

to consume no more than 1500 mg of sodium per day, and meet the potassium

recommendation (4700 mg/day) with food.

USDA, US Department of Agriculture; DASH, Dietary Approaches to Stop Hypertension.

Adapted from: US Department of Agriculture: Dietary guidelines for Americans. Available at: http://www.health.gov/DietaryGuidelines/.

Accessed July 22, 2006.

4Special Concerns of the Adolescent and Adult Male

to make serving sizes and food choices easier tocomprehend by the public. A Web site highlight-ing this diet (http://www.mypyramid.gov)allows individuals to receive a personal, tailoreddiet regimen plan. This in turn creates an indivi-dualized approach to balancing nutrition andexercise, which is promoted to lead to a betterlifestyle. Unfortunately, the basic pyramid

AFigure 19-2. A, Anatomy of MyPyramid. (Adapted from: MyPyraMyPyramid_Anatomy.pdf. Accessed July 22, 2006.)

366

contains no text and has an abstract illustrationthat limits its usefulness to individuals withaccess to it—persons with access to the Web siteor a full copy.

The Diabetes Prevention Program57 examinedthe USDA diet in a 27-center, randomized, clinicaltrial that evaluated the effects of lifestyle inter-vention and pharmacotherapy on the incidence

mid.gov. Available at: http://www.mypyramid.gov/downloads/

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BFigure 19-2. B, MyPyramid—Steps to a Healthier You. USDA, US Department of Agriculture. (Adapted from: MyPyramid.gov. Available at: http://www.mypyramid.gov/downloads/MiniPoster.pdf. Accessed July 22, 2006.)

19Nutrition

of type 2 diabetes in persons with impairedglucose tolerance. In this study, 3234 overweightparticipants (32% men) were randomly assignedto one of three groups: (1) placebo plus standardlifestyle recommendations, (2) metformin plusstandard lifestyle recommendations, and (3)intensive lifestyle intervention. Participants inthe medication and placebo groups wereprovided written information on the food guidepyramid and were seen annually in individualsessions. Patients in the intensive lifestyle groupalso followed the food guide pyramid butreceived closer follow-up. Participants in theintensive lifestyle group lost significantly moreweight than those in the metformin and placebogroups. The intensive lifestyle group also hada significantly lower incidence of type 2 diabetesthan the placebo or metformin group at 1 year.

AHA Diet

The AHA changed its dietary recommendationsfor 2006 introducing the “No-Fad” Diet.58 The

AHA acknowledges that losing weight is difficultand designed this diet based on three conceptsthat allow each individual to personalize aweight-loss plan (Figure 19-3).

Think Smart. According to the AHA, goodplanning, rather than sheer willpower, is the keyto losing weight. They advocate planning day-to-day activities to support weight-loss effortsbecause this will make it easier to maintain weightloss. Other key recommendations include thefollowing:

� Think about something that representsinner strength and use this image to boostthe self resolve needed for successful weightloss.

� Set reasonable, realistic, and measurableshort- and long-term weight-loss goals.

� Write goals in a weight-loss diary to makethem real.

� Reassess progress every 6 weeks and makechanges accordingly.

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CFigure 19-2. C, MyPyramid—Steps to a Healthier You. USDA, US Department of Agriculture. (Adapted from: MyPyramid.gov. Available at: http://www.mypyramid.gov/downloads/MiniPoster.pdf. Accessed July 22, 2006.)

ThinkSmart!

Eatwell!

MoveMore!

Figure 19-3. AHA diet. (Adapted from: American HeartAssociation. Available at: http://www.americanheart.org.Accessed July 22, 2006.)

4Special Concerns of the Adolescent and Adult Male

368

� Be persistent and practice new behaviorsuntil they become habit.

Eat Well. The emphasis here is on not only fol-lowing a diet plan until weight is lost, butmaking a commitment to choose foods wisely.Other helpful tips include the following:

� Set a personal weight-loss goal and startwith a goal of losing about 10% of currentbody weight.

� Keep a food diary.� Watch nutrition labels.� Include high-fiber foods, such as wholegrains, fruits, and vegetables, in your dietsince they take longer to digest and makeyou feel full longer.

� Identify the nonessential, high-calorie foodsbought out of habit, and stop buying them.

Move More. The AHA agrees that diet alone isnot enough. Regular physical activity is neededto help lose the weight and maintain the weightloss. Activity is an integral part of the recommen-dations, which include the following:

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Fignih

19Nutrition

� Decide on a personal fitness goal and writeit down. Start at 10 minutes each day, andprogress to 30–60 min/day.

� Choose an activity that fits into your life-style because that increases the likelihoodof maintaining it.

� Find a friend who will join in the activity.� Set aside a 30-minute block of time each dayto devote to the activity.

� Make physical fitness a priority in life.� Monitor progress, and reassess every 6weeks.

DASH Diet

The DASH eating plan was designed from theDietary Approaches to Stop Hypertension clinicalstudy funded by the National Heart, Lung, andBlood Institute in 1997.59 This study found thatpopulations who consume diets rich in vegeta-bles and fruits have lower blood pressures thanthose whose diets are low in vegetables. In addi-tion to fruits and vegetables, this diet is rich indietary fiber, potassium, calcium, and magne-sium, and protein (Figure 19-4).

In the original DASH trial, Appel and col-leagues59 evaluated 459 patients who had hyper-tension and, after a 3-week run-in period,subjects were randomly assigned to a control diet(rich in fruits and vegetables) or a DASH-typediet. At 8 weeks, there was a significant decrease

ure 19-4. The DASH diet pyramid. (Adapted from: National H.gov/health/public/heart/hbp/dash.)

in blood pressure of 5.5 mm Hg in the DASHgroup. More recently, the PREMIER60 trial investi-gated the effects of the DASH diet combined withrecommendations known to lower blood pressure(e.g., sodium and alcohol restriction, exercise,weight loss) and evaluated for reductions inweight and hypertension. A total of 810 partici-pants were randomly assigned to a control group(including a single advice-giving session for con-suming a DASH diet) or one of two interventiongroups. One intervention group followed theDASH diet and exercised. The other was encour-aged to participate in calorie restriction and exer-cise. There was significantly greater weight lossin both intervention groups at 6 months, with thegreatest weight loss noted in patients whofollowed the DASH diet and exercise plans.

A further modification of the DASH diet wasconducted in the OmniHeart Randomized Trial.61

This three-armed trial compared a standard dietsimilar to the DASHdiet withmodified diets basedon the DASH diet with either high proportions ofproteins or monounsaturated fats. One hundredsixty-four patients (55% men) were enrolled andwere crossed-over to each diet at 6-week intervals.Compared with the standard DASH diet, partialsubstitution of carbohydrates with either mono-unsaturated fats or proteins provided improvedblood pressure control and lipid levels andreduced estimated cardiovascular risk.

eart, Lung and Blood Institute. Available at: http://www.nhlbi.

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4Special Concerns of the Adolescent and Adult Male

Mediterranean Diet

There is not a universal “Mediterranean” diet.Many countries border the Mediterranean Sea,and differences in culture, ethnicity, and agricul-ture lead to variations in their diets. In additionto the well-known Mediterranean diet, LatinAmerican and Asian diet pyramids have also beendevised; these are based on similar principles butuse traditional ethnic foods in place of those foundin the Mediterranean region. These diets havebeen clearly illustrated and explained by the Old-ways Preservation and Exchange Trust.62 Regard-less of their background, all Mediterranean-stylediets have a few things in common (Figure 19-5):

� Abundant use of olive oil� High consumption of fruits, vegetables,breads, nuts, fish

� Limited amount of red meat

The Mediterranean diet does not regard allfat as unhealthy. The emphasis is not to limit fatconsumption, but rather make good choices

MEAT

The Traditional Healthy Med

Daily beveragerecommendations:

6 glasses of water

Wine inmoderation

SWEETS

EGGS

POULTR

FISH

OLIVE O

BREAD, PASTA, RICE, COOTHER WHOLE GRAI

DAILY PHYSICA

FRUITS BEANS,LEGUMES

& NUTS

CHEESE

Figu re 19-5. The Mediterr anean food diet pyramid. (Adappyramid.h tml. Accessed July 24, 2006.)

370

about the types of fat to include in the diet. Thisdiet is low in saturated and trans-fats, but highin omega-3 fatty acids and monounsaturated fats.Omega-3 fatty acids are found in fatty fishincluding salmon, trout, and sardines, whereasmonounsaturated fat is abundant in olive oil,nuts, and avocados.

A popular ingredient in the Mediterraneandiet is olive oil, which is predominantly monoun-saturated fat. Olive oil has been shown to alsodecrease triglycerides and increase HDL levels.63

In addition to improving the lipid profile, oliveoil may contribute to the cardioprotective effectof the Mediterranean diet in several other ways,including lowering blood pressure, providingantithrombotic effects, and improving insulinsensitivity.64

Fish consumption has long been recognized asimportant in the prevention of coronary arterydisease (CAD). In the United States Physicians’Health Study65 of more than 20,000 men over 11years, consumption of more than one serving of

Monthly

Weekly

Daily

iterranean Diet Pyramid

Y

IL

USCOUS, POLENTA,NS & POTATOES

L ACTIVITY

VEGETABLES

& YOGURT

ted from: Oldways. Available at: http://old wayspt.org/ med_

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19Nutrition

fish per week was associated with a 52% decreasein sudden cardiac death. The Nurses HealthStudy66 supported this finding and found a nega-tive relation between fish intake and risk of coro-nary heart disease. This protective effect is likelythe result of the cardiovascular benefits ofomega-3 fatty acids, which include lowering tri-glyceride levels and providing anti-inflammatoryeffects.

In the Diet and Reinfarction Trial,67 2033 menwith prior myocardial infarction were randomlyassigned to receive different kinds of dietaryadvice. After 2 years, the group that was advisedto increase omega-3 fatty acid intake by eatingfish or taking a fish oil supplement had a 29%reduction in mortality from any cause. In theGISSI-Prevenzione study,68 a 3½-year trial involv-ing more than 11,000 patients, the administrationof a supplement containing 850 mg of omega-3fatty acids decreased the risk of sudden cardiacdeath by 45% and improved all-cause mortalityby 20%, even in patients who were alreadyreceiving standard therapies (e.g., beta-blockers,statins, and aspirin).

In addition to proteins, carbohydrates, andfats, nuts contain other important nutrientsincluding fiber, vitamin E, folic acid, potassium,and magnesium. Although nuts do contain a highproportion of fat, most of it is in the form ofmonounsaturated fat and omega-3 fatty acids.Several large studies have examined the relation-ship between the risk of heart disease and intakeof omega-3 fatty acids from plant sources. In theHealth Professionals Follow-up Study,69 whichinvolved over 43,700 male healthcare profes-sionals, increased intake of alpha-linolenic acid(found in nuts) lowered the risk of a heart attackby 60%. The Seventh-Day Adventist HealthStudy,70 which had more than 31,000 partici-pants, found that eating nuts more than fourtimes per week had a 50% CAD risk–loweringeffect. Similar results were seen in the Nurses’Health Study,66 which found eating nuts regu-larly cut CAD risk by 35%, compared with theresults in those who rarely ate nuts.

Vegetarian Diet

According to a Time/CNN poll in 2002,71 4% ofthe US population identified themselves asvegetarian. People usually choose vegetarian dietsfor religious, ethical, or health reasons. Vegetariansdo not eat meat, chicken, or fish, and their dietconsists mostly of plant-based foods such as fruits,vegetables, whole grains, legumes, and nuts. Thistype of diet contains less total fat and cholesteroland includes more dietary fiber.

In the early 1970s, Frank Sacks,72 through hiswork at the Harvard School of Public Health,demonstrated that blood pressure and plasmalevels of lipids were lower in vegetarians thanin persons who ate meat. The American DieteticAssociation now states that vegetarian diets areassociated with a reduced risk of obesity, hyper-tension, hyperlipidemia, type 2 diabetes mellitus,coronary heart disease, and some forms of cancerincluding prostate, colon, and other gastrointesti-nal malignancies.73 This is thought to be due to ahigher intake of fruit, vegetables, fiber, and anti-oxidants and a lower intake of saturated fat andcholesterol (Figure 19-6).

Some of the strongest epidemiologic evidencein support of vegetarian diets has been providedby the China-Oxford-Cornell Diet and HealthProject (the China Study). The China Study wasa collaboration between Cornell University,Oxford University, and the Chinese Academy ofPreventive Medicine and examined the relation-ship between diet and the risk of developing dis-ease.74 The study’s concept was rooted in dataand hypotheses linking Western-style diets withincreased risks of chronic disease summarizedby the National Academy of Sciences in 1982.75

The project collected mortality data on more than50 diseases from 130 villages in 65 rural countiesin China. Blood, urine, and food samples and die-tary data were collected from 50 adults in eachvillage from 1983 to 1984 and combined withhistorical mortality data from 1973 to 1975.

A follow-up study (the China II Study), resur-veyed the same 6500 persons in 1989–1990,adding mortality data from 1986–1988 as well asparticipants from new counties in China and Tai-wan. The results were published in a manu-script,76 spawning dozens of studies, abstracts,and reviews and eventually a best-selling bookfor the public.77 Although strictly an observa-tional study, multiple papers spawned from thestudy reached several conclusions and generatedmany more hypotheses. Increased plasma choles-terol levels were associated with animal proteinintake and positively associated with increasedcancer mortality rates. Cardiovascular diseasewas also associated with increased animal proteinintake (such as casein) but not plant protein (suchas gluten). Western-type diseases, in aggregate,were significantly correlated (although not defini-tively caused) with increasing concentrations ofplasma cholesterol, which are associated in turnwith increasing intakes of animal-based foods.78

Vegetarians can be subdivided into groupsdefined by the types of animal-based foods theyeat:

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EGGSAND SWEETS

EGG WHITESSOY AND

DAIRY

WHOLE GRAINS

FRUITS ANDVEGETABLES

LEGUMESAND BEANS

PLANTOILS

NUTSAND SEEDS

Vegetarian Diet Pyramid

Daily beveragerecommendations6 glasses of water

Alcohol inmoderation

Daily physicalactivity

Weekly

Daily

At everymeal

Figure 19-6. The vegetarian diet pyramid. (Available at: http://www.vpul.upenn.edu/ohe/HealthLinks/vegetarian-pyramid.jpg.Accessed July 24, 2006.)

4Special Concerns of the Adolescent and Adult Male

� Lacto-ovo vegetarians: eliminate meat,slaughterhouse products, fish, and poultry,but eat/drink eggs, milk, and milk products

� Ovo-vegetarians: eat eggs but not dairyproducts

� Lacto-vegetarians: eliminate meat, fish,poultry, and eggs, but eat/drink milk andmilk products

� Vegans: eliminate all foods from animals,including meat, slaughterhouse products,fish, poultry, milk, eggs, and dairy products

� Fruitarians: restrict vegan diet to fruits, nuts,honey, and olive oil

� Macrobiotic vegetarians: restrict vegan diet,stressing whole grains and vegetables

The greatest risks associated with inadequatenutrient intake from a vegetarian diet occur dur-ing periods of growth. The more restricted thediet, the more difficult it is to get all of the neces-sary nutrients. Yet, vegetarians can meet theirnutritional needs with a carefully planned dietwith particular attention to a few nutrients. Asdiscussed earlier, plant proteins are incomplete.To correct this deficiency, vegetarians should beencouraged to add milk and eggs to their diet,since these items have an equivalent amount ofessential amino acids to animal protein, or to eat

372

soybean products, which have all essential aminoacids with the exception of methionine.

Concerns about iron nutrition arise from the dif-ferences between heme (meat-based) and non-heme(plant-based) iron. Since heme iron is more readilyabsorbed than non-heme iron (15–35% and 2–20%,respectively), vegetarians should include vita-min C sources with each meal to enhance absorp-tion of non-heme iron, and they should avoidheavy intake of tea, which inhibits iron absorp-tion. In addition to cow’s milk, other excellentvegetarian sources of calcium include dark greenleafy vegetables, dried figs, blackstrap molasses,soy milk, and calcium-fortified cereals, pastas,and tofu.

Plant foods do not contain vitamin B12 exceptwhen they are contaminated or processed bymicroorganisms. Thus, vegetarians need to lookto other sources to get vitamin B12 in their diet.Although the minimum requirement for vitaminB12 is quite small (1–2 mg/day), B12 deficiencycan lead to anemia and irreversible nerve dam-age. Possible vitamin B12 sources include eggs,milk, and milk products for lacto-vegetariansand B12-fortified soy milk, B12-fortified meatanalogs, and vitamin B12 supplements forvegans.

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19Nutrition

Weight Watchers

The Weight Watchers diet is a commercial dietprogram based on a low-calorie and low-fat phi-losophy.79 The program uses a point system thatencourages a sensible diet consisting of healthy,ordinary foods, exercise, and a positive attitude.The plan is flexible and allows considerablevariability and choice, but it requires relativelystrict caloric restriction. In addition to the actualdiet, in-person group meetings and weigh-insare important parts of the program that encour-age adherence to the plan.

The Weight Watchers diet has proven effectivein weight loss in multiple studies. A systematicreview of the effectiveness of five commercialdiet programs compared eDiets.com, HealthManagement Resources, Take Off Pounds Sensi-bly, OPTIFAST, and Weight Watchers.80 Of threerandomized, controlled trials of Weight Watch-ers, the largest reported a loss of 3.2% of initialweight at 2 years. Although most of the dietsshowed a large weight loss, most were associatedwith high-cost, high-attrition rates and a highprobability of regaining weight. With the excep-tion of Weight Watchers, the review found poorevidence to support other commercial weight-loss programs. A separate randomized trial com-pared two low-carbohydrate diets (Atkins andThe Zone) with a low-fat cardiac diet (the OrnishDiet) and Weight Watchers.81 Each diet achievedbetween 2 and 3 kg of weight loss at 1 year andsignificantly reduced the LDL/HDL cholesterolratio by approximately 10% but had no signifi-cant effects on blood pressure or glucose levels.Adherence for all the diets was considered poor.

Healing Foods and Healthy FoodsPyramids

The Healthy Foods Pyramid was designed in2001 and revised in 2005 as an evidence-basedresponse to the USDA Food Pyramid. It promotesthe treatment and prevention of disease throughan evidence-based diet, including whole grains,eliminating refined starches, and reducing redmeat and dairy intake.82 The Healing Foods Dietis a recent addition to low-fat diets (Figure 19-7).The diet includes principles of a plant-based dietwith components of food that are healthy forboth the individual and the earth.83 Alcohol,especially wine (which contains saponins, resver-atrol, and tannins), dark chocolate (which containbioflavonoids), and teas (which contain multipleantioxidants) are included as daily accompani-ments because of their phytochemical content.

Monounsaturated and polyunsaturated fats fromolive or canola oil, nuts, seeds, and avocado arerecommended. Five tenets are emphasized:

� Healing foods: Only foods that contain highproportions of essential nutrients and thosewith established healing properties areincluded.

� Plant-based choices: Plants constitute themajority of the diet; in particular, two to fourservings of fruit and essentially unlimitedservings of vegetables are recommended.

� Variety and balance: Balance and variety ofcolor, nutrients, and portion size areencouraged.

� Support of a healthful environment: Personsare encouraged to make food selections soas to be respectful of environment, empha-sizing organic foods raised without or withminimum additions of pesticides, hor-mones, medications, or contaminants.

� Mindful eating: Dieters are reminded to eatslowly and enjoy and focus on what isconsumed.

Low-Carbohydrate Diets

Currently, one of the most popular approachesto weight loss is the low-carbohydrate diet(Table 19-4). In 2003, a systematic review includ-ing over 107 studies, 24 of which were rando-mized controlled trials, evaluated the efficacy ofthese diets.84 The analysis concluded that the dietswere generally effective but that weight loss wasassociated with decreased caloric intake, ratherthan true amount of carbohydrates in the diet.Both low- and higher-carbohydrate dieters lostsimilar amounts of weight (2–3 kg) and had nodifferences in cardiovascular effects after 90 days.Proponents of these diets argue that high glyce-mic carbohydrates are the cause for the weightgain because they result in a rapid rise in bloodsugar followed by a surge in insulin. This insulinsurge decreases blood sugar levels, which in turnresults in craving for more carbohydrates, whichresults in more food ingestion and subsequentconversion into triglycerides. It is thus hypothe-sized that the body then continually needs glu-cose and relies on food as opposed to burning itsown fat. These diets focus on changing the body’sfuel source from dietary carbohydrates to adiposetissue. These diets are sometimes referred to asketogenic diets because the increase in fat break-down commonly results in ketone production.

Since low-carbohydrate diets are generallyhigh in protein content (which has been shownto be more hunger satisfying than carbohydrates

373

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Accompaniments

Lean Meats

Fish & Seafood

Legumes

Water

Grains

VegetablesFruits

Eggs Dairy

Seasonings Healthy Fats

Healing Foods Pyramid

Weekly

Daily

Optional

Figure 19-7. The Healing Foods Pyramid. (University of Michigan Integrative Medicine: Healing Foods Pyramid. 2004. Availableat: http://www.med.umich.edu/umim/clinical/pyramid/index.htm. Accessed July 24, 2006.)

4Special Concerns of the Adolescent and Adult Male

or fats), dieters often consume fewer totalcalories, which aids in the weight loss. Finally,low-carbohydrate diets can induce significantwater diuresis as a result of glycogenolysis fromincreased protein consumption. As glycogenstores (which are bound to water) are consumedfor energy, two to four times that amount inweight-equivalent free water is diuresed throughthe urine. Thus, a portion of the early weight lossin these diets is simply water weight.85

Many versions of the low-carbohydrate dietexist, each with a unique interpretation of opti-mal low-carbohydrate eating.

The Atkins Diet

The Atkins Diet (Figure 19-8) was first publishedin the 1970s by Dr. Robert Atkins86 but did notgain popularity until the late 1990s. The dietworks by promoting a 2-week induction phasethat restricts carbohydrates to 20 g/day, followedby an ongoing weight-loss phase that slowlyincreases carbohydrates in at a rate of 5 g/week.Finally, a maintenance phase with a goal carbo-hydrate level of 40–90 g/day is entered; thisphase is designed to maintain weight loss.

374

In 2003, Foster et al87 randomly assigned 63obese people to follow either the Atkins diet or aconventional low-fat, low-calorie diet. Althoughthe Atkins group had statistically significantgreater weight loss at 3 months, there was no sig-nificant difference in weight loss, total cholesterol,or LDL cholesterol levels at 1 year. However, thesubjects in the Atkins group did have greaterHDL cholesterol and lower triglyceride levels.

South Beach Diet

The South Beach Diet was based on the 2003best-selling book by Dr. Arthur Agatston.88

It incorporates some of the elements of the Atkinsdiet but in a less restrictive form. Phase 1 of the dietlimits fat tomonounsaturated sources and includesonly low-GI carbohydrates. As the various phasesprogress, the proportion of carbohydrates increasesand the proportions of fat and protein decrease. Inphase 2, “healthy carbohydrates” with a low GI areintroduced slowly. Here, each dieter’s reaction tocarbohydrates is monitored by their weight tomake changes necessary to continue to lose weight.Finally, lifelong maintenance (phase 3) is reachedwhen the right balance between intake and weight

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Table 19-4. Low-Carbohydrate/High-Protein Diet Summaries

Atkins Zone Protein Power Sugar Busters Stillman South Beach

Diet philosophy Eating excess CHO

releases insulin in large

quantities,

contributing to obesity

and health problems.

Restricting CHO intake

leads to ketosis, which

decreases hunger and

increasing metabolism.

Three phases are

involved.

Eating the right

combination of foods

to optimize metabolic

functions lowers insulin

levels and desirable

eicosanoid levels, thus

leading to decreased

hunger, weight loss,

and increased energy.

Eating CHO releases

insulin in large

quantities, which

contributes to obesity

and other health

problems.

Sugar is “toxic” to the

body and causes

release of insulin,

which promotes fat

storage.

High-protein foods

burn body fat. If CHO

are consumed, the

body stores fat

instead of burning it.

Eating the “right

carbs” and the

“right fats”

results in health

and weight loss.

“Bad carbs”

create urges to

overeat and store

fat.

Three phases are

involved.

Foods to eat All meats, fish, poultry,

eggs, cheese, low-CHO

vegetables

40% CHO, 30% protein

(based on lean body

mass), 30% fat

15–35% CHO, 30–45%

protein (based on lean

body mass), 30–50% fat

Protein and fat Lean meat and fish,

skinless poultry

Meat, poultry, and

fish, reduced-fat

cheese, eggs

Butter, oils Mono fats, lean meats Meat, fish, poultry, eggs,

cheese

Low-GI foods Eggs Healthy oils and

nuts

No alcohol Low-GI foods Low-CHO vegetables Olive oil, canola oil in

moderation

No alcohol Vegetables

Mega vitamins and

mineral supplements

daily (MVIs

recommended)

Alcohol in moderation High fiber (25 g/day) Alcohol in moderation Skim milk, skim cheeses

and cottage cheese

“Right

carbohydrates

and sweets”—low

GI

200 IU vitamin E Butter, oil, salad

dressings

Fruits must be eaten

alone

Three meals and

two snacks

Alcohol in moderation 3 meals/day Dessert after dinner

8 glasses water/day

MVI, vitamin C,

chromium, potassium

Menu analysis

(based on

computer

analysis of 2–3

days menus

provided in

books)

1st 2 weeks: 1400 kcal/

day; 28 g/day CHO

(8%); 125 g/day protein

(36%); 83 g/day fat

(53%); 29 g/day

saturated fat (19%);

5 g/day fiber

1430 kcal/day; 135 g/day

CHO (38%); 111 g/day

protein (31%); 50 g/day

fat (31%); 14 g/day

saturated fat (9%);

17 g/day fiber (protein

requirement based on

1.6 g/kg)

1475 kcal/day; 47 g/day

CHO (13%); 110 g/day

protein (30%); 86 g/day

fat (52%); 32 g/day sat

fat (20%); 14 g/day

fiber; increase CHO

gradually

1000 kcal/day; 114 g/

day CHO (46%); 71 g/

day protein (28%);

28 g/day fat (25%);

7 g/day saturated fat

(6%); 16 g/day fiber

1038 kcal/day; 7 g/day

CHO (3%); 162 g/day

protein (64%); 80 g/

day fat (33%); 13%

saturated fat

1st 2 weeks:

1409 kcal/day;

72 g/day CHO

(20%); 122 g/day

protein (35%);

67 g/day fat

(43%); 20 g/day

saturated fat

Table continued on following page

19Nutritio

n

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Table 19-4. Low-Carbohydrate/High-Protein Diet Summaries (Continued)

Atkins Zone Protein Power Sugar Busters Stillman South Beach

(13%); 15 g/day

fiber

Ongoing weight loss

phase: 1840 kcal/day;

33 g/day CHO (7%);

161 g/day protein

(35%); 118 g/day fat

(58%); 39 g/day

saturated fat (19%);

6 g/day fiber

Ongoing weight

loss phase:

1220 kcal/day;

125 g/day CHO

(41%); 70 g/day

protein (23%);

53 g/day fat

(38%)

Maintenance phase:

1800 kcal/day; 128 g/

day CHO (31%); 110 g/

day protein (24%);

80 g/day fat (40%);

31 g/day saturated fat

(16%); 20 g/day fiber

Foods to limit or

avoid

CHO; specifically, bread,

pasta, most fruits and

vegetables, milk

CHO; specifically, bread,

pasta, fruit (some

types)

CHO limited to 30 g/day

in phase 1, 55 g/day in

phase 2, increase in

maintenance

Potatoes, white rice,

corn, carrots, beets,

white bread, all

refined white flour

products

All CHO: specifically,

bread, pasta, fruit

(some types)

Phase 1: Fatty

meats; whole

milk cheese; high-

GI vegetables; all

fruit; fruit juices;

all starchy foods,

all dairy; alcohol

1st 2 weeks: CHO 20 g/

day CHO

Saturated fats and

arachidonic acid

Count CHO from alcohol Vegetables Phase 2: bagels,

white flour,

potatoes, white

rice); beets;

carrots, corn;

bananas; canned

fruit, juice,

pineapple

Ongoing weight loss:

gradual increase in

CHO over 2 months

Fats, oils

Maintenance diet: 25–

90 g/day CHO

Dairy products

CHO, Carbohydrates; GI, glycemic index; MVI, multivitamin.

Adapted from: St. Jeor ST, Howard BV, Prewitt TE, et al: Dietary protein and weight reduction: a statement for healthcare professionals from the Nutrition Committee of the Council on Nutrition, Physical

Activity, and Metabolism of the American Heart Association, Circulation 104:1869–1874, 2001; and from the Registered Dietitians at the University of Michigan Cardiovascular Center.

4Sp

ecia

lConcernsoftheAdolesce

ntandAdult

Male

376

Page 29: Clinical Men's Health || Nutrition

NO

THE ATKINS LIFESTYLE FOOD GUIDE PRYAMID™

Whole grain foods such as—barley, oats, and brown rice IN

CR

EA

SE

OP

TIO

NS

WIT

H A

DD

ITIO

NA

L EX

ER

CIS

E

Vegetable and seed oils, cheeseand dairy, nuts and legumes

Fruits such as—blueberries,raspberries, pears, and avocados

Vegetables such as—saladgreens, broccoli, cauliflower,asparagus, and spinach

Protein sources such as—poultry, fish, beef,pork, and soy products

HERE’S WHAT YOU DO: ADDED SUGARS & HYDROGENATED OILS

Tofu

1.2.

3.

4.

Limit and control certain carbohydrates to achieve and maintain a healthy weight.Choose carbohydrates wisely (vegetables, fruits, legumes, whole grains), avoidingrefined carbohydrates and foods with added sugars.Eat until you are satisfied:–to maintain weight, eat in proportion to the pyramid.–to lose weight, focus on protein, leafy vegetables and healthy oils.Everyone’s metabolism and lifestyle are different. Discover your individual carb level toachieve and maintain a healthy weight. Raise this level with additional exercise.

Figure 19-8. The Atkins Diet pyramid. (Available at: http://www.atkins.com. Accessed July 24, 2006.)

19Nutrition

is reached. In 2004, Aude and colleagues89 ran-domly assigned 60 obese patients to follow eitherthe South Beach Diet or a low cholesterol diet. At3 months, weight loss was almost double in theSouth Beach group (13.6 versus 7.5 pounds) withno statistically significant differences in the lipidprofiles between the two groups.

Other Low-Carbohydrate Diets

The Zone Diet90 and the Sugar Busters Diet91 arealso modified low-carbohydrate diets that allow40% of calories from carbohydrates. The ZoneDiet recommends a balanced approach of 40%carbohydrates, 30% protein, and 30% fat and areturn to the diet of our human ancestors, wheremeats, fruits, and vegetables were the main die-tary sources. This plan theoretically achieves thecorrect ratio of carbohydrates to proteins and fatsto control basal insulin levels. According to itsauthor, Barry Sears, PhD,90 this diet optimizesthe body’s metabolic function through the regula-tion of blood glucose.

The Sugar Busters Diet91 not only promotesavoidance of high glycemic carbohydrates butalso encourages the consumption of monounsatu-rated fats such as olive and canola oils. Theauthors of this diet also stress the avoidance ofsaturated and trans-fats to reach a balanced nutri-tional concept. A modified food pyramid is cre-ated that emphasizes moderation in portionsizes and the consumption of grains, fruits, andvegetables.

In 2002, Bouche and colleagues92 examinedwhether glucose, lipids, and total fat mass couldbe improved in nondiabetic men by adhering toa low-GI diet similar to the Zone or Sugar BusterDiet. Participants in the low-glycemic group wereinstructed to consume foods with a GI less than45 (e.g., proteins, tofu, nuts, seeds, berries, avoca-dos, and most vegetables), whereas those in thehigh-GI group were asked to consume foods witha GI greater than 60 (e.g., white bread, white rice,potatoes, sweets). No significant changes in bodyweight were observed during the 5 weeks in

377

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4Special Concerns of the Adolescent and Adult Male

either group; however, those who consumeda low-glycemic diet had lower postprandialplasma glucose, cholesterol, and triglyceridelevels than their counterparts.

There are many other low-carbohydrate dietsavailable. Some of the more popular include theProtein Power and Protein Power Lifeplan, theScarsdale Medical Diet (Dr. Tarnower’s Diet),and one of the earliest low-carbohydrate diets,The Doctor’s Quick Weight Loss Diet (i.e., theStillman Diet).

Dietary Guidelines for thePrevention and Managementof Chronic Disease

Lifestyle modifications including healthier dietarychoices and exercise are always recommended asfirst-line treatment for obesity, hypertension, dia-betes mellitus, and cardiovascular disease. Thisnext section examines the evidence for specificdietary recommendations that have been evalu-ated as part of this first-line treatment.

Obesity

The prevalence of obesity is rapidly increasingworldwide, with more than 64% of US adultsoverweight or obese by BMI according to resultsfrom the 1999–2000 National Health and NutritionExamination Survey (NHANES).93 This figurerepresents a 14% increase in the prevalence ratefrom NHANES III (1988–1994) and a 36% increasefrom NHANES II (1976–1980) (Table 19-5). Menhave lower rates of obesity than women (27.7%versus 34% between the ages of 20 and 74 years),although prevalence for men has more thandoubled since the first NHANES survey in 1960–1962, in which just 10.7% of males were obese.94

Despite its prevalence, the prevention and man-agement of obesity remains controversial.

Table 19-5. Prevalence of Obesity from 1988 to 2000

MEN PREVALENCE (%)

Age (Years) 1988–1994 1999

20–34 14.1 2

35–44 21.5 2

45–54 23.2 3

55–64 27.2 3

65–74 24.1 3

75 and older 13.2 2

Adapted from: National Center for Health StatisticsPrevalence of overw

Availa ble at: http://www .cdc.gov/nchs/ products/pubs /pubd/hestats/obe s

378

A review of the literature reveals that manystudies demonstrating that calorie restriction canachieve short-term weight loss, yet the lack oflong-term, high-quality trials has led to a lack ofconsensus among clinicians regarding the bestdietary approach to treat obesity.

In November 2004, the Cochrane Database ofSystematic Reviews updated Advice on Low-fatDiets for Obesity.95 This was a collection of allavailable randomized clinical trials of low-fatdiets versus other weight-reducing diets. Thisreview focused on adults who were overweightor clinically obese and were dieting for the pur-pose of weight reduction. The main outcomemeasure was weight loss, and the participantswere followed up for at least 6 months. Theresults of this systematic review showed no sig-nificant difference between low-fat diets andother weight-reducing diets in terms of long-termweight loss. In most of the studies, there weresmall, nonsignificant differences in weight lossbetween low-fat diet groups and the comparisongroups. The two main limitations of this reviewwere the lack of long-term studies and largelosses of participants to follow-up.

Currently, a systematic review is being col-lected by the Cochrane group evaluating low-GI diets for obesity.96 Until the results of thatreview are revealed and more long-term clinicaltrials undertaken, there will continue to bemuch controversy about the type of weight-lossdiet that can be proven to be most efficacious inthe long-term treatment and management ofobesity.

Hypertension

Although a variety of dietary modifications havebeen shown to be beneficial in treating hyper-tension, approximately 50 million persons inthe United States are still affected. In fact, a

WOMEN PREVALENCE (%)

–2000 1988–1994 1999–2000

4.1 18.5 25.8

5.2 25.5 33.9

0.1 32.4 38.1

2.9 33.7 43.1

3.4 26.9 38.8

0.4 19.2 25.1

eight and obesity among adults: United States, 1999–2002.

e/obse99.htm.

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19Nutrition

relationship between weight loss and decreasedblood pressure was first noted as early as the1920s.97 Since then, many trials have demon-strated that weight loss in overweight patients,salt and alcohol restriction, and incorporation ofa vegetarian or DASH-type diet (see Figure 19-4)can improve blood pressure.98

Solid evidence for weight loss was collectedby the Cochrane group in a 2005 systematicreview.99 This review sought to evaluate whetherweight-loss diets are more effective than regulardiets in controlling blood pressure. Eighteen ran-domized controlled trials involving 2611 partici-pants concluded that weight-reducing diets inoverweight hypertensive persons resulting inweight loss of an average of 3–9% of body weightare associated with a decrease of 3 mm Hg ofboth systolic and diastolic blood pressure.100

The workshop on Sodium and Blood Pressurewasconvened by the National Heart, Lung, and BloodInstitute in Bethesda, MD, in January 1999. Itreviewed evidence from the previous decade onthe relationship between sodium intake and bloodpressure. The group concluded that a highersodium intake is associated with higher bloodpressure levels and that blood pressure can belowered with reductions in sodium intake reduc-tions in sodium intake of 40–50 mmol in bothhypertensive and nonhypertensive persons.100

In 2001, Sacks and colleagues101 evaluated theeffect of varying sodium intake in combinationwith consumption of a DASH diet. In this study,412 participants were randomly assigned to fol-low either a control or a DASH diet and, withineach diet, participants ate foods with three differ-ent levels of sodium content for 30 days. Theirfindings revealed that reducing sodium intaketo levels below 100 mmol/day and the DASHdiet both lower blood pressure substantially.The greatest effects were observed in the low-sodium DASH group that had decreases in bloodpressure comparable to those observed with anti-hypertensive patients.

Diabetes Mellitus

Lifestyle modifications including diet and exer-cise have been considered to be effective first-linetreatment for type 2 diabetes for many years. TheUS Diabetes Prevention Program Study57 demon-strated that the onset of type 2 diabetes can beprevented—or at least delayed—with dietaryeffort and increased physical activity. A diet withgreater low-fat dairy intake was found to lowerthe risk for type 2 diabetes in men in the HealthProfessions Follow-up Study, which examined

41,254 male patients.102 Yet, the optimal diet forpatients with diabetes remains controversial. Sig-nificant amounts of carbohydrates worsen hyper-glycemia, whereas fats increase the risk ofatherosclerosis, and proteins may promote dia-betic nephropathy. In 2004, the ADA updatedits statement on the topic103 and provided the fol-lowing top-level evidence-based recommenda-tions based on multiple population risk strata:

� Foods containing carbohydrates from wholegrains, fruits, vegetables, and low-fat milkshould be included in a healthy diet.

� With regard to the glycemic effects of carbo-hydrates, the total amount of carbohydratesin meals or snacks is more important thanthe source or type.

� Less than 10% of energy intake should bederived from saturated fats.

� Dietary cholesterol intake should be lessthan 300 mg/day.

� In insulin-resistant persons, reduced energyintake and modest weight loss improveinsulin resistance and glycemia in the shortterm.

� Structured programs that emphasize life-style changes, including education, reducedfat (< 30% of daily energy) and energyintake, regular physical activity, and regularparticipant contact, can produce long-termweight loss on the order of 5–7% of startingweight.

� Exercise and behavior modification are mostuseful as adjuncts to other weight-loss stra-tegies. Exercise is helpful in the mainte-nance of weight loss.

� Standard weight-reduction diets, when usedalone, are unlikely to produce long-termweight loss; structured intensive lifestyleprograms are necessary.

The Cochrane Database of Systematic Reviewsexamined all randomized trials of 6 months’ dura-tion or longer in which dietary advice was themain intervention in adults with type 2 diabetes.104

Data from 36 articles reporting a total of 18 trialsmonitoring 1467 participants were collected. Dif-ferent dietary approaches, as well as the additionof exercise to each diet, were the main analyses,whereas weight and micro- and macrovasculardiabetic complications were the main outcomemeasures. Unfortunately, there were insufficientdata in the review to reach any valid conclusionsregarding the type of dietary advice most suitablefor patients with diabetes. However, there wassolid evidence for the use of exercise as an adjunctto dietary modifications because this was asso-ciated with a statistically significant decrease in

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4Special Concerns of the Adolescent and Adult Male

mean glycosylated hemoglobin levels of 0.9% at 6months and 1% at 12 months.22

Currently, the National Institutes of Health isevaluating the long-term health effects of weightloss in adults who are overweight and have type2 diabetes. This new study entitled “LookAHEAD” is well underway and will follow upwith participants for up to 11 years, whichshould help clarify the role of dietary treatmentin type 2 diabetes.

Metabolic Syndrome

The constellation of dyslipidemia, elevated bloodpressure, impaired glucose tolerance, and centralobesity defines the metabolic syndrome. TheNational Cholesterol Education Program–AdultTreatment Panel III (NCEP-ATP III) identifiedmetabolic syndrome as an independent riskfactor for cardiovascular disease and consideredit an indication for intensive lifestyle modifica-tion.105 The two essential components of lifestylemodification are diet and exercise. Since skeletalmuscle is the most insulin-sensitive tissue in thebody, it should be a primary target for affectinginsulin resistance. Physical training has beenshown to reduce skeletal muscle lipid levels andimprove insulin resistance, regardless of BMI.106

Unfortunately, very few randomized con-trolled trials exist to specifically examine thetreatment of metabolic syndrome with specificdietary interventions. Azadbakht and col-leagues107 conducted a randomized controlledoutpatient trial conducted on 116 patients withthe metabolic syndrome. These patients wereassigned to follow one of six diets and were fol-lowed up over a period of 6 months. Relative tothe control diet, the DASH diet resulted in higherHDL cholesterol (7 and 10 mg/dL), lower trigly-cerides (�18 and �14 mg/dL), lower systolicblood pressure (�12 and �11 mm Hg), lower dia-stolic blood pressure (�6 and �7 mm Hg), lowerweight (�16 and �14 kg), decreased fastingblood glucose (�15 and �8 mg/dL), anddecreased weight (�16 and �15 kg) among menand women, respectively (all P < .001).

Cochrane Database systematic reviews108,109

support the role of dietary interventions in helpingto reduce cardiovascular risk. These reviewsdemonstrated that a low-sodium diet was enoughto maintain a lower blood pressure after with-drawal of antihypertensive medications and alsoshowed that low-fat diets in which participantswere involved for more than 2 years showed sig-nificant protection from cardiovascular events (rel-ative risk, 0.84; 95% confidence interval, 0.72–0.99).

380

Coronary Artery Disease

An important emphasis of the latest AHA dietaryguidelines for the secondary prevention of CAD(last updated in 2006)110 is lipid management.The recommendations include the following:

� Dietary therapy should proceed in allpatients, including a goal of less than 7%of caloric intake provided by saturated fatand an intake of less than 200 mg dietarycholesterol and trans-fatty acids per day.

� LDL cholesterol should be less than 100 mg/dL (at baseline or on medical treatment);levels less than 70 mg/dL are also reason-able, especially in persons with diabetes.

� Triglyceride levels should be less than150 mg/dL and HDL cholesterol levelsshould be greater than 40 mg/dL (at base-line or on medical treatment).

� The goal BMI should be 18–25 kg/m2.� Increased intake of omega-3 fatty acids inthe form of fish or capsules should beencouraged.

Early studies with conventional dietary modi-fication (National Cholesterol Education ProgramStep 1 and 2 diets) yielded little benefit on estab-lished coronary disease; however, more positiveresults were reported in the early 1990s,111 withaggressive dietary therapy aimed at reducingdietary saturated fat and cholesterol. The St.Thomas Atheroma Regression Study (STARS)randomly assigned men with coronary heartdisease and total cholesterol levels exceeding232 mg/dL to receive conventional care versus alow-fat diet with a target cholesterol consumptionof 100–120 mg/day. At 3 years, the diet-treatedgroupwas noted to have a slower progression rateof coronary atherosclerosis, more regression ofcoronary atherosclerotic lesions based on angiog-raphy, and less severe angina pectoris.111 TheLyon Diet Heart Study112 evaluated the effects ofa Mediterranean diet in 605 patients after a firstmyocardial infarction. At 27 months, patients fol-lowing this diet had lower rates of deaths andmyocardial infarctions (primary end points) aswell as unstable angina, stroke, heart failure, andpulmonary embolisms (secondary end points).This benefit was also noted up to 4 years.

The Cochrane Group recently examined theAHA’s advice regarding omega-3 fatty acidsin the treatment of cardiovascular disease ina recent review.113 They collected data from 48randomized controlled trials including 36,913participants. Pooled trial results did not showa reduction in the risk of total mortality orcombined cardiovascular events in persons

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taking additional omega-3 fats. They concludedthat there is no evidence to advise people to stoptaking rich sources of omega-3 fats, but furtherhigh-quality trials are needed to confirm sugges-tions of a protective effect of omega-3 fats oncardiovascular health.

The Portfolio Diet is a special low-fat dietdesigned to reduced cholesterol.114 A researchintervention, rather than a commercial service orbook, it was designed as a “portfolio” of currentrecommendations from the NCEP-ATP III andthe AHA Step II diet for foods that are knownto reduce cholesterol. This portfolio of choles-terol-reducing foods was compared with statinmedications in a randomized trial. This vegetar-ian diet is low in saturated fat and encouragesplant sterols and viscous fibers, soy protein, andalmonds. Psyllium, in the form of Metamucil,barley, and oats were preferred grains; eggplantsand okra were preferred vegetables. Margarineand butter were substituted with spreads con-taining omega-3 fatty acids and plant sterols,such as Benecol, Take Control, and SmartBalance. In this small trial, 25 men and 21 womenwere randomly assigned to participate in one ofthree interventions for 1 month: a control stan-dard low-fat diet based on milled whole-wheatcereals and low-fat dairy foods, the same dietplus lovastatin 20 mg/day, or the dietary portfo-lio. Results from the diet showed a significant dif-ference between the control diet, which reducedcholesterol by 8% and C-reactive protein (CRP)by 10%, and the other two arms.22 The controldiet plus lovastatin reduced cholesterol by 31%and CRP by 33% and was not significantly differ-ent than the dietary portfolio, which reducedcholesterol by 29% and CRP by 28%.22

Other Diseases

Persons with chronic gastrointestinal diseases,such as peptic ulcer disease, gastroesophagealreflux disease, malabsorptive syndromes, andinflammatory bowel disease, should adhere tospecific diets that treat the symptoms of thedisease or prevent problems associated with it.Persons with chronic pulmonary diseases, suchas chronic obstructive pulmonary disease andcystic fibrosis, and patients with chronic renalinsufficiency and renal failure also benefit fromadherence to a diet specifically designed toaddress their medical problems. For men withthese problems, specific consultation with aphysician regarding nutritional issues should beencouraged.

Fostering Change

Physicians should take an active role in guidingtheir patients toward their nutritional goals. Thisshould include not only educating them regard-ing the different dietary choices but also assistingthem in setting reasonable goals that are possibleto maintain. Because no one superior diet exists,the choice of an acceptable diet is not as impor-tant as its incorporation as part of an overallhealthy lifestyle. The importance of regular phys-ical activity is not to be underestimated becauselong-term weight loss and maintenance of opti-mal weight and body composition is difficultwithout exercise. Scheduled-interval patientfollow-ups for support and tracking progressare of great importance because they willdecrease the likelihood of relapse into poor die-tary habits. Finally, both physicians and dietingpersons need to be patient and flexible becausesuccessful weight loss is a long-term process thatis both challenging and rewarding. The followingbasic steps provide the groundwork towardachieving dietary goals:

� Provide a thorough evaluation of a patient’snutritional status in the context of his over-all health.

� Educate and devise a plan together.� Set realistic short- and long-term goals.� Consider early referral to a nutritionist ordietitian as well as other medical subspecia-lists when indicated.

� Monitor and track changes through use ofa food diary, and review it at scheduledvisits.

� Provide support and encouragement alongthe way through frequent follow-up visits.

� Be flexible and consider changing the plan ifcompliance is a concern.

� Be available for any questions or problemsthat may arise.

Conclusion

Diet plays a critical role in the etiology of chronicdisease and as an adjunct to treatment. Despitegrowing public awareness and scientific research,the incidence of chronic diseases such cardiovas-cular disease and diabetes continue to increase.Various dietary options exist that can potentiallyminimize morbidity and mortality in bothhealthy patients and in those with chronic dis-eases. Patients should consult their physiciansas to proper guidance regarding dietary recom-mendations, employing dietitians and nutritionalcounselors when available.

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