Biochemical principles of nutrition

1. Biochemical principles of nutrition 1

2. 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".

3. In various historical times structure of nutrition and character of a nutrition changed depending 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 was formed gradually depending on an economic and cultural level of development of the country, in view of national customs and features. Through centuries, food has been recognized as important for human beings in health and disease.

4. 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.

5. '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 commonsensereally.             

6. Main rules of healthy nutritional • Eating 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

7. Nutrition as a science can be regarded as the study of six main categories of food components protein minerals fat vitamins carbohydrate water

8. Water Water 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 2litersof 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.

9. Diseases, that is direct or mediate related with a nutrition 4. Disease, which are transferred by a nutritional way (some infectionsdiseases and intestinal worms, alimentary poisonings). 1.Alimentarydisease, illness caused by deficiency or surplus of components of nutrition. 3. Disease of multifactor nature that very much frequently develops on a background of genetic predilection, for example, atherosclerosis, gout, idiopathic hypertension, etc. 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.) 5. Alimentary intolerance - atypical reaction to nutrition, for example alimentary allergy, idiosyncrasy.

11. Body building and repair Function of nutrition Provision of energy Maintenance and regulation of tissue functions

12. CLASSIFICATION OF FOODS

13. 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.

14. 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

15. 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.

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

17. 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.

18. 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".

19. 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.

20. Sources of protein Plant sources: Animal sources:

21. Protein requirements Doctors recommended 1,0 g. protein/kgbody 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.

22. Effects of protein deficiency: The effects of protein deficiency may summarized as below. During pregnancy: Still birth, low birth weight, anemia Infancy and early childhood: Marasmus, kwashiorkor, mental retardation, stunted growth and development

23. 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.

24. 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.

25. 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.

26. Animal sources: These are ghee, butter, fat of meat, fish oils, etc. Vegetable sources: These are various vegetable oils such as groundnut, gingely, mustard, cottonseed, safflower (kardi) and coconut oil.

27. CARBOHYDRATES Chemically carbohydrates are composed of carbon, hydrogen and oxygen as the name implies. Polysaccharides are various starches which are converted into two molecules saccharides i.e. cane sugar, beet sugar, milk sugar and malt sugar. These on further, glucose and digestion change into single molecule monosaccharides fructose. Foods that are high in carbohydrates: Breads, pastas, beans, potatoes, bran, rice and cereals.

28. The original source of all starches and sugars is green plants. When plants have excessive sugar and they need to store it, as reserve supply of food, plant body is capable of changing its sugar into starch. Carbohydrates are abundantly present in food. All carbohydrates have to be changed into glucose and fructose before they can be absorbed into the body. 1 gm of carbohydrates yields 4.1 calories of heat. The daily requirement of carbohydrates varies from 50 to 60% of total energy intake. The carbohydrates are chief sources of energy. In the active muscles, the glucose is oxidized for the production of energy and warmth. Glucose which cannot be used imme­diately, is converted into glycogen and stored in the liver and muscles or converted into fat and stored under the skin.

29. There are three main sources of carbohydrate: Starches: These are present in cereals (rice, wheat); roots and tubers (potatoes). • Sugars: • Monosaccharides: glucose, fructose, galactose. • (b) Disaccharides: Sucrose, lactose, maltose. • (c) Cellulose: This is the tough fibrous lining found in vegetables, fruits, cereal, etc. • It is hard to digest and has no nutritive value. However, cellulose acts as "roughage" and prevents constipation.

30. VITAMINS These are complex organic substances contained in food and are very essential for the normal growth and nutrition of animals. In fact, they are vital accessory food factors required for the maintenance of optimum, health. They are present in various foods in minute quantities and diet devoid of vitamins, if taken for some period, gives rise to certain diseases known as deficiency diseases and may ultimately even cause death. They do not supply energy but are simply protective foods.

31. vitamins Fat-soluble Vitamins Water-soluble Vitamins Thiamine (B1)  A (retinol) Riboflavin (B2) Niacin (B3)  E (tocopherol)  Pyridoxine (B6) Pantothenic acid D (calciferol) Cobalamin (B12) Folic acid K (menadione) Ascorbic acid

32. 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.

33. 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.

34. 3. Mineral Deficiencies • 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.

35. 4. Vitamins Deficiencies (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. • Lack of vitamin A results in xerophthalmia, Bitot's spots, night blindness and keratomalacia.

36. 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.

37. 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

38. (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 charac­terised 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)Fluorosisoccurs 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.

39. Food allergies Some 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.

40. The hygienic characteristics of some food-stuff and their sanitary examination

41. Wheat It is the most important of all cereals and is extensively used all over the world. It contains 60-70 % starch, 8-12 % gluten and 15 % water. The seeds have an outer envelope called pericarp, which is very hard. It is composed mainly of cellulose and mineral matter and forms about 13 % of the grain. A middle layer called endosperm or kernel consists chiefly of starch. It forms 85 % of the grain. The germ or embryo forms about 1.5 % of the entire grain. It is rich in protein and fat. Flour is prepared by grinding up wheat.

42. Rice In fact, it forms the staple article of diet for half the population of the world. In composition, it is poorest in proteins, fats and mineral matter, out of all the cereals and has no cellulose contents or roughage. Its chief constituent is starch, which is in a very digestible form. It is digested within 3-4 hours. Being rich in starch it is eaten with nitrogenous and fatty substances, like pulses, fish, ghee etc., to supply the deficiency in proteins and fats. The bulkiness of rice eaters' diet gives rise to two important consequences: (i) it tends to prevent the absorption from the intestines of the proteins and vitamins contained in other foods eaten with it, as dais or pulses (ii) it is apt to cause disten­sion of the stomach and bowels with fermentation of their contents, thus result in indigestion and bowel complaints. The outer layer or pericarp contains vitamin B1 and its complete removal may give rise to beri-beri in rice eating population. Rice does not contain vitamins A, C and D.

43. Barley. It is very nutritious and is characterized by its richness in mineral salts and fat but is poor in gluten, so it is unsuited for making bread. Maize. It is as nutritious as wheat, and richer in fats than all cereals except oats. It contains 10 % proteins, 65 % carbohydrates, 5 % fats, 1-2 % salts and 14 % water. Maize is poor in certain amino acids—such as tryptophane. It is deficient in vitamins, the anti-scorbic and anti-pellagra factors being absent and an exclusive use of maize may cause pellagra. Oats or Jao. These are highly nutritious. They are deficient in vitamins A and D and gluten. Oats are used as oatmeal porridge and should be eaten with plenty of milk.

44. Pulses These are mostly legumes and are richer in nitrogenous substances that other vegetable foods. Pulses include peas, beans, and lentils. Owing to their richness in proteins, they are called "poor man's meat". Compared to meat, pulses are deficient in fat. Pulses also contain a good deal of carbohydrates If their fresh state they contain vitamins A, B, and C, but when dried they lose vitamin C. Soya Bean It is the richest form of vegetable proteins but with low fat content, a large amount of mineral matter and almost complete absence of starch. Iron content of soya beans varies from 7-30 mg. per 100 gms. The protein is of good quality and easily digestible. It contains large quantities of vitamin B1 but no vitamin C and D. A milk from soya bean is prepared to resemble more or less the composition of cow's milk. It contains absolutely no cholesterol. The high fibre content of soya milk helps relieve constipation, while high mineral protein and vitamin (especially B complex) levels provide "ideal"nutrition.

45. Roots and Tubers. They exist chiefly in the form of starch which is about 80 % proteins and fats being practically absent. They contain some mineral matters which are mainly salts of potash. The common form of tubers are carrots, potatoes, beet-root, radish, onions, arrow-root, sago and tapioca. Potatoes are rich in carbohydrates and contain starch 22 %, protein 2 % and a trace of fat (0.16 %). They are a good source of vitamins B and C and contain iron and phosphorus; that is why they are universally used as wholesome and palatable dietary articles having much nutritive value. Green Vegetables. They have little nutritive value, but form an important article of diet on account of the presence of vitamins and mineral salts of sodium, calcium and chlorine, which they contain. In composition they consist of 90 % water, 2 % nitrogenous substance or proteins, 4 % starch and ½ % fats. They contain large amount of alkaline salts which act as "buffers" and maintain the alkalinity of the blood. They supply vitamins A, B1, B2 and C and give relish to the food, so their inclusion is essential in an ideal dietary. Green vegetables are rich in cellulose, so add bulk and are of value in curing chronic constipation. So far as possible, they should be eaten raw as salad.

46. Fruits Fruits contain a large amount of sugar, vegetable acids and salts. These are protective foods. According to their nutritive value fruits have been divided into food fruits and flavouring fruits. Food fruits are those which afford nutriment, and include bananas, dates, figs, grapes, mangoes etc. Their nutritive value depends on the presence of carbohydrates, which exist in the form of sugar and commonly known as levulose or fruit sugar. Certain fruits such as lemons and oranges are rich in potassium salts, lime and magnesia and contain vitamin C. • The fruits are valuable because: • They have cooling effect and quench thirst. • They contain important mineral salts of potash combined with vegetable salts. • They have anti-scorbutic properties being the richest sources of vitamin C and for this reason they are included in children's dietary. They prevent scurvy. • They prevent constipation.

47. Nuts. They differ from fruits as they have higher calorific and nutritive value, being rich in proteins and fats. The common nuts are almonds, cocoa nuts, ground nuts, walnuts etc. They are rich in vitamin B but contain very little vitamin A and no vitamin C.

48. Meat It consists of muscle-fibres held together by connective tissues. The fibres of meat contain muscle plasma or muscle-juice. It contains 1 to 2 % salts which are chiefly chlorides and phosphates of potash. The proteins of meat which are present to the tune of about 17 to 20 % are myosin, muscle-albumen and haemoglobin. Fat (10 to 20 %) is often embedded in the connective tissues of meat. Inspection of Meat. Anti-mortem inspection of animals should be done, wherever possible and the animals should be rejected, if they appear to be ill. The carcase should be inspected after slaughtering whole and also part by part and subsequently organ by organ. Mediastinal and bronchial lymphatic glands should be examined for evidence of tuberculosis. If the animal has suffered from jaundice, the flesh will have a yellow tinge. Characteristics of Good Meat. The muscle fibres are of deep red colour and marbelled with fat. The reaction should be acidic. It should be firm, elastic to touch. It should have little or no odour as diseased meat emits odour of putrefaction or sickly smell. The fat should be firm and of whitish or yellowish grey colour. Lymphatic glands should be free from all diseases. Any diseased condition, i.e., cysts of tapeworms etc., should not be present.

49. Unsound Meat. • It is that meat which has begun to putrefy. • It becomes soft, moist, pale and often has greenish colour. • The reaction becomes alkaline • Оdour of putrefaction may commence in the deeper part of the meat especially near the bones and so the odour may not be apparent from the outer surface. Therefore, in case of suspected meat, it is advisable to push an iron skewer deep into the meat; pull it out and smell it. • The smell should be sweet and agreeable. • The juice should be reddish and acidic, since alkalinity is an indication of decomposition. • Putrified meat is extremely dangerous, as poisonous substances get developed, which introduce sudden and fatal illnesses due to ptomaine poisoning.

50. Diseased Meat • The flesh of animals killed by accident, lightning or those who happen to be suffering from diseases like anthrax, rabies, glanders, general tuberculosis etc., should be condemned. The diseased meat should be condemned and prevented from sending into the market. • The chief diseases of animals are: • Tuberculosis. • Cysticercus. • Trichinella Spiralis. • Actinomycosis or Ray Fungus. • Distomum Hepaticum of Liver Flukes.