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Biochemical principles of

nutrition

Nutrition may be defined as the science of food and its relationship to health. It is concerned primarily with the part played by nutrients in body growth, development and maintenance. The word nutrient or "food factor" is used for specific dietary constituents such as proteins, vitamins and minerals. Dietetics is the practical application of the principles of nutrition; it includes the planning of meals for the well and the sick. Good nutrition means "maintaining a nutritional status that enables us to grow well and enjoy good health".

In various historical times structure of In various historical times structure of nutrition and character of a nutrition changed nutrition and character of a nutrition changed depending ondepending on

development of industrial forces of a society, climate-geographical conditions, direction of economic activity and so on. The character of nutrition of the population The character of nutrition of the population

was formed gradually depending on an economic and was formed gradually depending on an economic and cultural level of development of the country, in view of cultural level of development of the country, in view of national customs and features.national customs and features.

Through centuries, food has been recognized as Through centuries, food has been recognized as important for human beings in health and disease.important for human beings in health and disease.

Good nutrition is a basic component of health. The relation of nutrition to health may be seen from the following view points:

• Growth and development: Good nutrition is essential for the attainment of normal growth and development. Not only physical growth and development, but also the intellectual development, learning and behaviour are affected by malnutrition.

• Specific deficiency: Malnutrition is directly responsible for certain specific nutritional deficiency diseases. Good nutrition therefore is essential for the prevention of specific nutritional deficiency diseases and promotion of health.

• Resistance to infection: Infection, in turn, may aggravate malnutrition by affecting the food intake, absorption and metabolism.

• Mortality and morbidity: The indirect effects of malnutrition on the community are even more striking - a high general death rate, high infant mortality rate, high sickness rate and a lower Expectation of life.

'You are what you eat', some people say. If you eat rubbishy food, you can't really expect to grow up strong and healthy.                                          

But if you eat good-quality food, you've a good chance of doing so. That's just commonsense really.                                     

Main rules of healthy nutritionalEating fruits, vegetables, and grain products that contain fiber may help prevent heart disease

Limiting the amount of saturated fat and cholesterol in your diet may reduce your risk of heart disease

Limiting the amount of total fat you eat may help reduce your risk for cancer

Eating fiber-containing grain products, fruits, and vegetables may help prevent cancer

Eating fruits and vegetables that are "low in fat" and "good sources" of dietary fiber, vitamin A, or vitamin C may help prevent cancer

protein

Nutrition as a science can be regarded as the study of six main categories of food components

vitaminsfat

water carbohydrate

minerals

WaterWater is necessary to make up the loss

caused by its excretion in breath, sweat, urine, faces, and also to renew all the various fluids and solid organs of the body.

It is estimated that about 2 liters of water enters the body daily as such or as a part of cooked food, beverages etc. Out of which 1.37 - 1.81 liters is excreted daily in urine, sweat etc.

Some important uses of water are: - As a solvent for transportation of nutrients in

the body. - It helps regulating body temperature

through evaporation from lungs and skin. - As an aid in removing wastes of metabolism in

the urine. - As an aid in functions like osmosis.

Diseases, that is direct or mediate related with a nutrition

1. Alimentary disease, illness caused by

deficiency or surplus of

components of nutrition.

4. Disease, which are transferred by a

nutritional way (some infections

diseases and intestinal worms,

alimentary poisonings).

5. Alimentary intolerance -

atypical reaction to nutrition, for

example alimentary allergy,

idiosyncrasy.

2. The secondary illnesses of insufficiency or excessive nutrition, which is developed as complication on a background of wearisome illnesses (surgical, infectious, oncology and others.)

3. Disease of multifactor nature

that very much frequently

develops on a background of

genetic predilection, for

example, atherosclerosis, gout, idiopathic

hypertension, etc.

Function of Function of nutritionnutrition

Body building and repair

Provision of energy

Maintenance and regulation of tissue functions

CLASSIFICATION OF FOODS

1.Classification by predominant functions:Energy-giving foods. These constitute fats and

carbohydrates. They are also called protein sparer. Proteins also produce energy to some extent. Cereals, roots and tubers, dried fruits, sugars and fats belong to this group. They supply heat and energy to the body.

Body building foods. These are foods rich in proteins, mineral salts and water. Milk, meat, fish, pulses, oilseeds and nuts fall in this category.

Protective foods. These constitute inorganic salts, vitamins and minerals. They include proteins and water. Milk, eggs, liver, green leafy vegetables and fruits are included in this group. They build our bones, teeth, muscles, soft tissues, blood and other body fluids. They provide material for repair in the body as wear and tear goes on constant.

2. Classification by origin:•Foods of animal origin•Foods of vegetable origin

3. Classification by chemical composition:

•Proteins•Fats•Carbohydrates•Vitamins•Minerals

4. Classification by nutritive value:•Cereals and millets•Pulses (legumes)•Vegetables•Nuts and oilseeds•Fruits•Animal foods•Fats and oils•Sugar and jaggery•Condiments and spices•Miscellaneous foods

Balanced diet is one, which will meet a person's caloric need and contain all nutrients, particularly proteins, and vitamins. In addition, the food should satisfy the taste and desire of a person and should have enough roughage to promote the peristalsis. Balanced diet should have 50-60 % carbohydrates 30-35 % fats and 10-15 % proteins with necessary vitamins and minerals. A balanced diet must contain foods from the above three groups.

Importance of the main components of food in nutrition of the man

Nutrients are organic and inorganic complexes contained in food. There are about 50 different nutrients which are normally supplied through the foods we eat. Each nutrient has specific functions in the body. Most natural foods contain more than one nutrient. These may be divided into :

(i) Macronutrients: These are proteins, fats and carbohydrates which are often called "proximate principles" because they form the main bulk of food.

(ii) Micronutrients : These are vitamins and minerals. They are called micronutrients because they are required in small amounts which may vary from a fraction of a milligram to several grams.

PROTEINSThe word "protein" means that which is of first importance. Indeed they are of the greatest importance in human nutrition. Proteins are composed of carbon, hydrogen, oxygen, nitrogen and sulphur in varying amounts. Some proteins also contain phosphorus and iron and occasionally other elements. Proteins differ from carbohydrate and fat in the respect that they contain nitrogen. Proteins are made up of simpler substances, called amino acids. These are the building blocks of proteinSome 22 amino acids are stated to be needed by the human body, out of which eight are called "essential".

Proteins are needed by the body:

• For growth and development: They furnish the building material, i.e. the amino acids from which the body proteins are synthesized.

• For repair of body tissues and their maintenance: It has been shown that the body proteins are constantly being broken down; they have to be replaced for which fresh protein intake is required.

• For synthesis of antibodies, enzymes and hormones: Antibodies, enzymes and hormones contain protein. The body requires protein to produce them.

• Proteins can also furnish energy to the body, but generally the body depends for its energy on carbohydrates and fats rather than proteins.

Protein requirementsDoctors recommended 1,0 g. protein/kg

body weight for an adult.

Daily allowances recommended by experts of the World Health Organization (Geneva, 1976) is 37 g of protein per day for the standard man with mass of body 65 kg for professions of average hardness (II group) and 29 g of protein for the standard woman with body mass 55 kg.

Effects of protein deficiency:The effects of protein deficiency may summarized as below.

During pregnancyDuring pregnancy: : Still birth, low birth weight, anemia

Infancy and early childhoodInfancy and early childhood: : Marasmus, kwashiorkor, mental retardation, stunted growth and development

Effects of protein deficiency:Effects of protein deficiency:Adults: Loss of weight, underweight, poor musculature, anemia, increased susceptibility to infection, frequent loose stools, general lethargy, incapacity to sustained work, delay in wound healing, cirrhosis of liver, oedema, ascitis, etc.

Fats are composed chemically of carbon, hydrogen and oxygen, only in different proportion than they are contained in carbohydrates. There is less of oxygen in fats than in carbohydrates. Fats are a form of concentrated food and like carbohydrates, they are used as body fuels for the production of heat and energy. As fats are not soluble in water, the process of digestion changes the fat into an emulsion form for their absorption into the body. Liquid fats and those which melt at body temperature are somewhat better digested than those which are much harder.

Fats serve the following functions: • Dietary fat is a concentrated source of energy. One

gram of fat supplies 9 calories of energy.

• Fats are carriers of fat-soluble vitamins, e.g., vitamins A, D, E and K.

• Dietary fat supplies "essential fatty acids". Linoleic acid, one of the essential fatty acids, prevents scaly skin formation.

• The fat layer below the skin plays an important role in maintaining our body temperature.

• Fats provide support for many organs in the body such as heart, kidney, intestine etc.

• Foods containing fats are tasty.

Vegetable sources: These are various vegetable oils such as groundnut, gingely, mustard, cottonseed, safflower (kardi) and coconut oil.

Animal sources: These are ghee, butter, fat of meat, fish oils, etc.

Water-soluble Vitamins

vitaminsvitamins

Niacin (B3) 

Fat -soluble Vitamins

Riboflavin (B2)

Folic acid

E (tocopherol) 

A (retinol)

D (calciferol)

K (menadione)

Pyridoxine (B6)

Thiamine (B1) 

Pantothenic acid  

Cobalamin (B12)

Ascorbic acid

Nutritional Diseases:

1. Protein Calorie Malnutrition (PCM). (i) Kwashiorkor. It results from consumption of very low

protein in diets of low biological values, yet providing just enough energy to satisfy the needs of the child. This condition is usually seen in children between the age group of 1-4 years. This symptom is characterized by pitting oedema, anemia, retarded growth, loss of appetite, diarrhoea, scanty hair growth...

(ii) Marasmus. It is a clinical condition of protein energy malnutrition, primarily due to total deprivation of the requisite calories required by the body. It usually occurs in the age group of 1/2 to 5 years. This syndrome is characterized by failure to gain weight, wasting of muscles and of subcutaneous fat. The child feels good appetite but is irritable.

(iii) Marasmic-Kwashiorkor. Patients suffering from Marasmic-Kwashiorkor show clinical symptoms of both Marasmus and Kwashiorkor.

2. Protein Deficiency in Adults.

Protein deficiency in adults is also quite prevalent in poverty areas.

Protein deficiency will result in adults having reduced weight, reduced subcutaneous fat, anaemia, greater susceptibility to infection, frequent loose motions, general lethargy, delay in healing of wounds oedema.

3. Mineral Deficiencies

(i) Deficiency of iodine in water and feed leads to goitre.

(ii) Lack of flourine ( < 0.5 ppm) in water leads to caries.

(iii) Calcium deficient diets lead to rickets and osteomalacia.

(iv) Iron deficiency diets lead to anaemia,

(v) There are other important minerals like copper, selenium etc. Usually their requirements are so little that deficiency conditions do not occur.

4. Vitamins Deficiencies (i) Lack of vitamin A results

in xerophthalmia, Bitot's spots, night blindness and keratomalacia.

(ii) B Complex: Deficiency of Thiamine leads to beri - beri.

Niacin deficiency results in pellagra.

Riboflavin deficiency symptoms are angular stomatitis, cheilosis, scrotal dermatitis and corneal vascularisation.

Other B Complex deficiencies also result in glossitis, cheilosis and angular stomatitis

(iii) Vitamin C deficiency leads to scurvy, spongy bleeding gums, haemorrhages in skin and other haemorrhages,

(iv) Vitamin D deficiency result in rickets and osteomalacia.

(v) Vitamin K deficiency leads to hypoprothrombinaemia, which further leads to haemorrhages.

5. Problems of Overnutrition (eating too much)

Proteins/fats/carbohydrates• Cardiovascular disease (Leading cause of death in

the western world); a primary cause is thought to be ingestion of saturated fat and trans fat

• Some cancers • Diabetes mellitus • Insulin resistance • Obesity The main features of obesity are overweight

and fatness. It is mostly caused by overeating and intake of abundance of calories

• Metabolic syndrome

Vitamins• Vitamin poisoning

(i) Hypervitaminosis A is at times caused by excess of vitamin A therapy. The manifestation are headache, nausea, vomiting, irritability and anorexia. Carotenaemia is also caused due to excessive consumption of carrots which is charac terised by yellow skin with normal conjunctiva

(ii) The toxic manifestations of hypervitaminosis D are anorexia, nausea, vomiting, thirst, polyuria and drowsiness. Calcium and phosphorus levels in serum and urine are raised. Calcium may be deposited in many tissues also

(iii) Fluorosis occurs if fluorine is available > 1,5 mg in water. It is characterised by (a) dental fluorosis, i.e., mottled enamel of teeth and (b) skeletal fluorosis i.e., dense bone formation, severe spondylitis and even calcifications of ligaments of spine and tendinous inflamation of other muscles in severe cases.

Food allergiesSome people have allergies or sensitivities to foods

which are not problematic to most people. This occurs when a person's immune system mistakes a certain food protein for a harmful foreign agent and attacks it. About 2% of adults and 8% of children have a food allergy.

Commonly food allergens are gluten, corn, shellfish (mollusks), peanuts, and soy. Most patients present with diarrhea after ingesting certain foodstuffs, skin symptoms (rashes), bloating, vomiting and regurgitation. The digestive complaints usually develop within half an hour of ingesting the allergen.

Rarely, the food allergy chelce can lead to anaphylactic shock: hypotension (low blood pressure) and loss of consciousness. This is a medical emergency. An allergen associated with this type of reaction is peanut, although latex products can induce similar reactions.

The hygienic characteristics of some food-stuff and their sanitary

examination

BASES OF TREATMENT - PROPHYLACTIC NUTRITION

Treatment-prophylactic nutrition – is a special nutrition for workers of harmful enterprises. The base of this nutrition is rational nutrition, which is structured according to metabolism of harmful substances in the human organism and curative action of some nutrients, which protect human organism from negative influence of chemical compounds and physical factors. Treatment-prophylactic nutrition is an obligate component of protective health-proving measures, directed on limitation of negative action of harmful factors on production on the organism.

Treatment-prophylactic treatment is directed on:

elimination of possibility of harmful substances penetration into internal medium of the organism from the digestive tract, meaning their binding in stomach and intestines;

quickening of excretion of harmful substances from the human organism;

increasing of general resistance of the organism towards harmful factors;

protection of certain, most damageable systems of the organism from harmful action of toxic substances;

quickening or on the opposite slowing down toxic substances metabolism in the organism (aiming to stop their income into internal medium).

Introduction of treatment-prophylactic nutrition as a rule follows after theoretical and medical-biological investigations directed on determination of mechanism of action of certain harmful substances and their combinations on the organism. Complex interrelations between components of the mixture are determined during studying of complex action of several toxic substances; as if they enter the organism together character of their toxic action may change (synergism or antagonism). After detoxic action of different nutritive products and substances is studied. It is proved that many nutrients have a considerable detoxicating action. Thus, pectin substances are able to bind heavy metals and radionuclide in digestive tract, preventing their absorption and entering internal medium of the organism. Sulfur containing amine acids methyonin, cystin, magnesium salts promote excretion of some toxic substances from the organism. Vitamins raise protective capabilities of the organism.

VEGETARIANISM

Vegetarianism is the practice of not consuming the flesh of any animal, with or without also eschewing other animal derivatives, such as dairy products or eggs. Some vegetarians choose to also refrain from wearing clothing which has involved the death of animals, such as leather, silk and fur. Veganism, sometimes called "strict vegetarianism", excludes all animal products from diet and attire, whether or not their production has involved the actual death of an animal (dairy, eggs, honey, wool, silk and down feathers). Vegetarians have varied motivations including religious, cultural, financial, ethical, environmental, and health concerns.

There are many different practices of vegetarianism. The following table summarizes the practices of various different

types of vegetarian diet:

Foods allowed in the main vegetarian diets

Diet Name Meat (includes fish) Eggs Dairy

Lacto-ovo vegetarianism

No Yes Yes

Lacto vegetarianism

No No Yes

Ovo vegetarianism No Yes No

Veganism No No No

Other dietary practices commonly associated with vegetarianism

Fruitarianism is a diet of only fruit, nuts, seeds, and other plant matter that can be gathered without harming the plant.

Macrobiotic diet is a diet of mostly whole grains and beans, though it allows the consumption of fish.

Natural hygiene in its classic form recommends a diet principally of raw vegan foods.

Raw veganism is a diet of fresh fruit, nuts, seeds, and vegetables.

Freeganism — argues that all commodities produced under capitalism, not only those from animal sources, contribute to exploitation and avoid buying anything, including food. Freegans thus focus on acquiring foods and other commodities by means other than purchasing, including dumpster diving, foraging for wild plants, and gardening with intent to cause as little violence and ecological destruction as possible through their consumption. While many freegans are vegans or vegetarians, others will eat animal products recovered from dumpsters that would otherwise go to waste on the belief that doing this does not encourage further animal exploitation.

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