CHAPTER Images shutterstock.com 2 Nutritional Needs

CHAPTER

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Nutritional Needs

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• Name the key nutrients, describe their functions, and list important sources of each.

• Analyze the effects of various nutrient deficiencies and excesses.

• Explain the processes of digestion, absorption, and metabolism.

Objectives


The Nutrients

• Food provides nutrients, which are necessary for good health

• Nutrition examines how the body uses nutrients

• If you do not eat the foods your body needs, you may suffer from malnutrition

continued


The Nutrients

• Nonessential nutrients are substances the body can make

• Essential nutrients are substances the body cannot make and must be supplied by the foods you eat

continued


The Nutrients

• There are six main groups of essential nutrients:1. carbohydrates

2. fats

3. proteins

4. vitamins

5. minerals

6. water

continued

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The Nutrients

• Failure to get enough of the needed nutrients may result in a deficiency disease

• Consuming too much of some nutrients can result in toxicity


Dietary Supplements

• Doctors may recommend dietary supplements to help make up for nutrient shortages in the diet

• Some dietary supplements provide nonnutrient substances, such as herbs and some antioxidants

continued


Dietary Supplements

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• Besides supplements, fortified foods can be a source of added nutrients


Carbohydrates

• Carbohydrates are the body’s main energy source

• They are classified as simple or complex based on molecular structure

• They are carried through the bloodstream in the form of glucose

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Functions of Carbohydrates

• Carbohydrates are sources of energy for the body and brain

• Fiber does not provide energy, but can help– reduce the risk of heart disease– speed food through the body– dilute carcinogens (cancer-causing agents)– reduce the risk of cancer


Sources of Carbohydrates

• Sugars, soft drinks, and candies are sources of simple carbohydrates

• Breads and cereals provide starches• Fruits, vegetables, and whole grains offer fiber

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Carbohydrate Deficiencies and Excesses• A carbohydrate deficiency can cause the

body to use protein as an energy source• This can interfere with the normal growth

and repair of body tissues and potentially create a chemical imbalance

• Consuming too many simple carbohydrates can result in nutrient shortages and excess calories


Fats

• Fats belong to a group of compounds called lipids

• Lipids, which include both fats and oils, contain fatty acids

• Based on the amount of hydrogen atoms found in their molecules, fatty acids are classified as saturated or unsaturated


Types of Fats

• Saturated fatty acids have as many hydrogen atoms as they can hold

• Unsaturated fatty acids have fewer hydrogen atoms than they can hold– monounsaturated– polyunsaturated

• Hydrogenation makes unsaturated fatty acids saturated and creates trans fatty acids

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Types of Fats

• Cholesterol is a fatlike substance that serves important functions in the body– Part of skin tissue– Aids in transport of fatty acids– Produces hormones


Think Further

Why don’t you need to add cholesterol to your diet?

Think Further

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Functions of Fats

• Supply energy• Carry certain types of vitamins• Enhance flavor in foods• Tenderize meats and baked goods• Protect organs• Insulate the body


Sources of Fats

• Eggs• Dairy products• Meats• Fish• Nuts • Vegetable oils• Olives• Avocados

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Fat Deficiencies and Excesses

• A diet low in fat may result in a loss of weight and energy

• Diets high in fat have been linked to heart disease, some cancers, and weight gain– No more than 35 percent of the calories in your

daily diet should come from fat– No more than 10 percent of total calories should

come from saturated fat


Proteins

• Proteins, the third category of essential nutrients, are made of amino acids– Essential amino acids– Nonessential amino acids

• Complete proteins contain all nine essential amino acids

• Incomplete proteins are missing one or more of the essential amino acids


Functions of Proteins

• Growth, maintenance, and repair of tissues• Formation of enzymes, some hormones,

and antibodies• Source of energy• Regulation of bodily processes


Sources of Proteins

• Meat• Poultry• Fish• Dairy products• Eggs• Dried beans• Nuts

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Protein Deficiencies and Excesses• A protein deficiency can lead to

protein-energy malnutrition (PEM)• Excess protein in the diet will be converted

to fat


In Your Opinion…In Your Opinion…

What is your favorite source of protein?

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In Your Opinion…


Vitamins

• Each vitamin serves unique functions• The body cannot produce most vitamins in

quantities large enough to meet nutritional needs

• A varied, nutritious diet is best to get the vitamins the body needs

continued


Vitamins

Fat-soluble vitamins – vitamin A– vitamin D– vitamin E– vitamin K

Water-soluble vitamins– vitamin C – thiamin – riboflavin – niacin– vitamin B6

– folate – vitamin B12

– pantothenic acid– biotin


Fat-Soluble Vitamins

• Vitamin A– aids the eyes with ability to see at night– promotes bone growth– keeps skin and other tissues healthy– found in liver, egg yolk, and whole milk– has higher values in orange and dark green

fruits and vegetables

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• Vitamin D– promotes the growth

and mineralization of bones and teeth

– found in eggs, liver, and fatty fish

– used to fortify most milk, cereal, and margarine

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• Vitamin E– acts as an antioxidant– protects red and white bloods cells, fatty acids,

and vitamin A– common in many food items, including fats and

oils, whole-grain products, liver, eggs, whole milk dairy foods, and leafy green vegetables

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• Vitamin K– aids in blood clotting– produced in the

intestinal tract– found in leafy green

vegetables, cauliflower, organ meats, and egg yolk

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Water-Soluble Vitamins

• Vitamin C (ascorbic acid)– helps form and maintain collagen, which holds

body cells together – firms the walls of blood vessels – helps heal wounds and broken bones– helps create hemoglobin and fight infections– functions as a dietary antioxidant– found in many fresh fruits and vegetables

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• B-complex vitamins work together in the body

– folate

– vitamin B12

– biotin

– thiamin– riboflavin– niacin

– vitamin B6

continued



• Thiamin (B1)– helps the body release energy from food and

promote normal appetite and digestion– found in nearly all foods except fats, oils, and

refined sugars

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• Riboflavin (B2)– helps break down carbohydrates– helps cells use oxygen – keeps skin, tongue, and lips healthy– found in milk, eggs, oysters, leafy green

vegetables, and whole-grain enriched cereal products

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• Niacin–helps keep the nervous system, mouth, skin,

tongue, and digestive tract healthy–helps cells use nutrients–found in meats, poultry, and peanuts–too much niacin can cause nausea, vomiting,

and red flushing

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• Vitamin B6

– helps nerve tissues function normally– aids with the regeneration of red blood cells– helps break down proteins, carbohydrates,

and fats– found in vegetables, muscle meats, and whole-

grain cereals

continued



• Folate– helps the body produce

normal blood cells– folic acid is especially

important during pregnancy

– found in green vegetables, yogurt, fruits, and whole-grain cereals

continued

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• Vitamin B12

– promotes normal growth

– aids in normal functioning of cells in bone marrow, nervous system, and intestines

– found in animal protein foods and cereals

• Pantothenic Acid– helps the body use

energy nutrients and make cholesterol

– promotes growth– found in plant and

animal tissues, yeast, and milk

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• Biotin– aids in the breakdown

of fats, carbohydrates, and proteins

– essential part of several enzymes

– found in kidney, liver, chicken, eggs, milk, fresh vegetables, and some fruits

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Vitamin Deficiencies and Excesses• Vitamin deficiencies can result in such

conditions and diseases as night blindness, rickets, scurvy, beriberi, pellagra, and anemia


Did You Know?

The term vitamin was originally vitamine, a combination of the words vita and amine. Vita is Latin for life. Amine referred to amino acids, which scientists initially thought were part of the make up of vitamins. The final e was later dropped when scientists learned that vitamins did not contain amino acids.

Did You Know?


Minerals

• The body needs at least 21 minerals for good health, which can be obtained from a variety of foods

• Macrominerals are needed in large quantities per day

• Trace elements, or microminerals, are needed in smaller quantities per day


Macrominerals

• Calcium – combines with

phosphorous to build and strengthen bones and teeth

– helps blood clot– keeps the heart and

nerves working properly– found in milk, fish, and

green vegetablescontinued

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Macrominerals

• Phosphorous– works with calcium

to build bones and teeth

– helps the body store and release energy

– found in meat, poultry, eggs, milk, and dairy products

continued© Joe Gough/Shutterstock


Macrominerals

• Magnesium– helps regulate the body’s temperature– keeps the nervous system working properly– found in whole grains and grain products, nuts,

beans, meats, and dark green leafy vegetables

continued


Macrominerals

• Sodium, chloride, and potassium– work as a team to control osmosis – help the nervous system and muscles function– help cells absorb nutrients– common in the food supply and U.S. diet– sources include table salt, many types of

seafood, many vegetables, and fruits


Trace Elements

• Iron– helps form

hemoglobin, which carries oxygen throughout the body

– found in animal sources and leafy green vegetables

• Zinc– aids the immune

system– promotes normal

growth and development

– found in meats and whole grains

continued


Trace Elements

• Iodine– helps regulate

energy usage rate– found in seafood

and iodized salt

• Fluoride– helps teeth develop

and resist decay– may maintain bone

health– found in water

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Mineral Deficiencies and Excesses

• Mineral deficiencies can cause such conditions as osteoporosis and goiter

• Research has shown there is a link between excess sodium amounts and hypertension

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Think FurtherThink Further

Why do you need to vary your diet in order to consume the essential nutrients?

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Water

• Water is the sixth essential nutrient

• Between 50 and 75 percent of body weight is water

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Functions of Water

• Water aids digestion, cell growth and maintenance, chemical reactions, joint lubrication, and temperature regulation in the body

• Nearly all beverages and foods provide some water


Water Intake and Excretion

• About 80 percent of water intake comes from liquids

• The body excretes most water through the kidneys as urine and the remaining through the skin, lungs, and feces © Jakub Pavlinec/Shutterstock


Water Requirements

• Most people should consume about 1 ounce of fluid for every 2 pounds of body weight

• Climate, health, and eating habits affect water needs

• Thirst is the first symptom of water loss• Too much water can result in water

intoxication, a rare condition


Digestion and Absorption

• Foods must go through the processes of digestion and absorption before the body can use the nutrients they contain

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The Digestive Tract

• The digestive or gastrointestinal tract is about 30 feet long– esophagus– stomach– small intestine– large intestine

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The Digestion Process

• Mechanical phase– begins in the mouth when teeth chew food and

break it down into smaller pieces– initiates contractions in the digestive tract,

known as peristalsis

continued



• Chemical phase– begins in the mouth when food mixes with

saliva– gastric juices break down food in the stomach– the semiliquid leaves the stomach and enters

the small intestine, where intestinal juices, pancreatic juices, and bile act on the food

continued



– digestive enzymes help break foods down into simple substances the body can absorb and use

– once digestion is complete, absorption can take place

– some substances then travel into the large intestine, which acts as a reservoir

– the body excretes these materials in the feces


The Absorption Process

• Most absorption takes place in the small intestine

• The small intestine is lined with millions of villi, which aid in absorption

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Metabolism

• Metabolism takes place in the cells after the body absorbs nutrients

• Nutrients follow a distinct metabolic path• Carbohydrates become glucose for energy

or glycogen for storage

continued


Metabolism

• During fat metabolism, fats become fuel• During protein metabolism, amino acids are

used for cell maintenance and growth or as energy


1. What are the six essential nutrients?1. carbohydrates

2. fats

3. proteins

4. vitamins

5. minerals

6. water

Review


2. What is one function of each of the key nutrients?Answers will vary.

3. What are two important sources of each of the key nutrients?Answers will vary.

Review


4. How can deficiencies and excesses of various nutrients affect the body?

nutrient deficiencies can result in deficiency diseases, protein-energy malnutrition, night blindness, rickets, scurvy, beriberi, pellagra, anemia, osteoporosis, hypertension, and goiter; nutrient excesses can result in toxicity

Review


5. What occurs in the body during the processes of digestion, absorption, and metabolism?

digestion breaks food down into simple materials the body can use; absorption involves taking in nutrients and making them part of the body; metabolism involves chemical processes that take place in the cells after the body absorbs nutrients

Review

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CHAPTER Images shutterstock.com 2 Nutritional Needs