Nutrition

Last Updated on Tuesday, 26 October 2010 08:27 Written by Sandesh Monday, 24 May 2010 02:57

NUTRITION
Nutrition: Process of obtaining necessary food for growth, development and maintenance of health. It can also be defined as acquiring of energy and raw-materials needed to maintain life.
Nutrients: Specific substances required for growth, developed and normal functioning of our body are called nutrients. They may be organic such as carbohydrates, lipids, proteins, and vitamins or organic such as mineral salts.
Diet: Nature and quantity of food we eat
Balanced diet: One which contains the correct proportions and quantity of the various, water and dietary
1. Carbohydrates:
Daily requirements: each gm of carbohydrates provides 80-85% of energy.
Carbohydrates include sugars and starch (a polysaccharide). Carbohydrates are major energy source, but sugars are also building blocks for more complex molecules such as nucleic acids, nucleotides (e.g. ATP, NAD) and glycogen.
2. Lipids:
Lipids include fats, which are solid at room temperature, and oils, which are liquid at room temperature. Like carbohydrates, lipids are major energy source. Fatty tissue forms a convenient long-term energy store in the body. Fats in the diet may also be a source of fat-soluble vitamins (A, D, E and K). Types of lipids:
i. Simple: esters of fatty acids and alcohols. E.g. fats, oil and waxes
ii. Complex- composed of fatty acids, alcohol and an extra group which may be carbohydrates
iii. Derived or precursor lipids- building blocks of lipids
Fatty acids: There is a large variety of fatty acids in foods, but all are either saturated or unsaturated. Saturated fatty acids have no double bonds. Fats are rich in saturated fatty acids. Unsaturated fatty acids have one or more double bond. Oils are rich in unsaturated fatty acids. A balanced diet will contain both saturated and unsaturated fatty acids.
Daily requirement: 20-30%of dietary fats.
Essential fatty acids (EFAs) are the one which must be included in the diet because it cannot be made in the body. Without it ill-health would result. Only two are strictly essential namely linoleic acid and alpha linoleic acid.
• EFAs are used in the manufacture of phospholipids which form part of structure of membranes
• Involved in transport, breakdown and excretions of cholesterol. Cholesterol is an essential component of membranes and are needed for the manufacture of steroids, including sex hormones and vitamin D. However excess cause atherosclerosis (fatty acid deposits in arteries)
Deficiency- EAFs deficiency is characterized by rough, dry scaly skin, hair loss, poor health etc.

3. Proteins:
Proteins are used mainly for growth and repair. They have many functions. They can also be used as source of energy if the diet is deficient in carbohydrate and fat.
Proteins are made up of amino acids. There are 20 different amino acids commonly used to make protein. Amino acids are either essential or non essential.
Essential amino acids- must be included in the diet because either it cannot be made in the body at all, or it is made too slowly to meet needs. Insufficient intake would result in ill health. Eight of 20 amino acids are required for adult human and ten for infants. Non-essential amino acids can be made from essential amino acids. Protein rich in essential amino acids are called first class or high quality proteins. They are commonly animal protein, found in milk and its products, meat, fish and eggs, but soya protein is useful source of first class protein for vegetarians. Other protein are referred to as second class or low quality proteins
4. Vitamins: (imp for exam)
Vitamins are organic compounds required in small quantities for good health. They cannot be made within the body, so must be present in the diet. If a given vitamin is lacking, a characteristic set of symptoms will develop known as a deficiency disease.
Name of vitamins and its designated letter Principle sources Function Deficiency Disease and symptoms
Fat soluble vitamins
A (Retinol) (imp.)* Fish-liver oil, liver
Milk and derivatives, carrots, spinach, watercress Control growth
Used to make retinal, which is an essential for the formation of the visual pigment rhodopsin. Helps in ni8ght vision Skin becomes dry, cornea becomes dry and mucous membrane degenerates. Poor night vision. Night blindness (xeropthalmia) or permanent blindness (keratomalacia)
D (Calciferol)* Fish-liver oil, egg-yolk, dairy products, margarine. Made by the action of sunlight on a cholesterol-like compound in the skin. Controls calcium absorption from the gut and concerned with the calcium metabolism. Important in bone and tooth formation. Aids in absorption of phosphrous. i. Rickets-Occur in children, -failure of growing bones to calcify, bowing of leg and bending of spine.
ii. Osteomalacia- an adult condition where bones are painful and spontaneous fractures
E (Tocopherol) Wheat germ, brown flour, liver, green vegetables Anaemia-increased breakdown of RBC
K (Phylloquinone) Spinach, cabbage, brussels, sprouts Necessary for blood-clotting mechanism Mild deficiency results in prolonged blood clotting time where as serious deficiency fails to clot blood
Water soluble vitamins
B1(Thiamin) Wheat germ or rice germ, yeast extract, liver, kidney, heart Acts as coenzyme for decarboxylation in respiration esp. in Kreb cycle Beriberi-nervous system affected
Muscles become weak, paralysis, heart failure. Oedema, retardation of growth in children.
B2 (Riboflavin)
Cheese, milk, yeast extracts Carbohydrate and fat metabolism and cellular oxidation Tongue sores, sores at the corners of mouth
B6 (Pyridoxine) Eggs, liver, kidney, whole grains, vegetables, fish Important in fatty acid and amino-acid metabolism Depression and irritability
B5 (Panthothenic) In most foods Involved in activation of carboxylic acids in cell metabolism Muscles cramp, fatigue, poor muscles coordination
B12 (Cyanocobalamin)* Milk, meat, cheese RNA nucleoprotein synthesis Anaemia
B3 (Nicotinic) Meat, whole meal bread, yeast extract, liver Essential component of co-enzymes NAD, NADP Skin lesions, rashes and diarrhoea
Folic acid (M or Bc) White fish, liver, green vegetables Formation of RBC. Synthesis of nucleoprotein Anaemia
H (Biotin) Yeast, egg-white, kidney, liver used as coenzyme for number of carboxylation reactions Muscles pain
C (Ascorbic acid)* Citrus fruits, green vegetables, potatoes, tomatoes, other fruits Metabolism of connective tissue and production of strong skin Skin of gums become weak and bleed. Anaemia. Heart fail.

4. Minerals
Minerals are inorganic and needed for a wide range of functions. Seven minerals are needed in only trace amounts for good health, and these are known as trace elements. They include manganese, copper, iron and iodine. Only tiny quantities of trace elements are required in the daily diet.
Major elements Sources Examples of functions
Calcium
Phosphorus/
phosphate

Milk and other products

Synthesis of bones and teeth
Synthesis of nucleic acids, ATP, phophoslipids
Sodium Table salt, fish, egg, milk and other foods Most common extra-cellular cation, transmission of nerve impulse, water and electrolyte balance, muscular contraction.
Potassium Found in all foods eg. Banana, honey, potato etc. Needed with sodium to maintain electrical potential across cell membranes
Iron Liver, meat, green leafy vegetables, cereals, nuts, legumes etc. Formation of haemoglobin, myoglobin. Regulation of body temperature and muscular activity
Magnesium Plant food and meat Calcium and potassium metabolism
Trace elements
Fluorine Drinking water, marine fish, cheese Mineralization of bones
Zinc Meat, milk sea food Forms components of enzymes like carbonic anhydrase and lactate, synthesis and storage of insulin
Copper Sea food, liver, kidney, fish, nuts, legumes etc Metabolism of iron, present in many enzymes
Cobalt Meat Part of B12
Manganese Meat, sea food Constitute some enzymes involved in respiration
Iodine Sea food, iodized salt, milk, meat, drinking water, onion Synthesis of thyroid hormone
Chromium Meat, cereals, pulses, spices Metabolism of carbohydrate, protein and lipids

RDA(Recommended Dietary Allowance)-average daily dietary intake
EAR (Estimated Average Requirement)
Nutritional deficiency diseases:
1. Kwashiorkor: It is the disease of the child removed from breast by birth of the next one. Switching the child from milk diet to a starchy diet leads to protein deficiency.
Signs and symptoms include:
• Hair becomes thin and fall off easily
• Oedema-swelling of body tissue with fluid
• Thin muscles, under weight and reduced growth, slow mental development
• Reduced resistance to infections
• Babies may cry continuously not responding to pain or comfort
2. Marasmus: Occurs when calorie deficiency is relatively high than protein deficiency. Usually seen in children younger than one year of age.
• Wizened and shrunken features, givi8ng face the appearance of old man’s face, with shrunken eyes
• Growth retardation, very underweight, reduced resistance to infection
Malnutrition: Malnutrition in its broad sense means bad nutrition, and can be applied to both undernutrition and overnutrition.
Obesity: Most common nutritional disease in Britain today and is just as a great problem in most European countries and in North America. Obesity is caused when energy input as a result of eating is greater than energy used.
Anorexia nervosa: slimmer disease. Loss of appetite through nervous cause. Results from dieting, common in society where people believe that thin is beautiful.
Protein energy malnutrition(PEM): Important cause of childhood mortality. Also leads top permanent impairment of physical and mental growth to those who survived.