VITAMINS

 

VITAMINS

 

                  Vitamins are the accessory indispensable food factors. They are organic in nature and are required in small quantities to maintain normal growth and regulation of metabolism. They have no tissue building role but are concerned with the regulation of chemical reactions of life. Lack of any one of them from the diet of the young animals slows down or prevent growth. Vitamin deficiency results in many diseases. The term vitamin was coined by Dr. Funk in 1912. Some vitamins are synthesized in our body while others are obtained through food. The vitamins are classified into two, Fat soluble vitamins and Water-soluble vitamins based on their solubility in water. Fat soluble vitamins are Vit. A, D, E and K. Water soluble vitamins are vit. B and C.

 

Fat soluble vitamins

Vitamin A (Retinol)

It is also known as antixerophthalmic or anti-infective vitamin.

Sources: This occurs only in animals, in liver, kidney, lungs, and fat deposit. Fish liver oils are good deposits of this vitamins. In plants, it occurs as carotene in carrots and sweet potatoes.

Function: It may be considered as a regulator growth and activity of epithelial tissues. It occurs in the retina of the eyes and is associated with a protein to form a visual purple or rhodopsin.

The deficiency of vitamin results in night blindness due to the inability to resynthesise rhodopsin.

Recommended dietary allowance for adults is 5000 IU

 

Vitamin D (Ergocalciferol)

It is also known as antirachitic vitamin or sunshine vitamin

Sources: Cod-liver oil, dairy products etc. It is manufactured in the skin of mammals under the influence of sunlight.

Physiological role: The primary function of vitamin D is to regulate the absorption as well as utilization of calcium and phosphorous. Hence it is important in bone and teeth formation. It increases both active and passive transport of calcium through the small intestine. Vitamin D also increases the volume of gastric secretion.

The deficiency of vitamin D result in Rickets and Osteomalacia

Recommended dietary allowance for adult is 40 IU

 

Vitamin E (Tocopherol)

It is also known as anti-sterility vitamin or fertility vitamin or reproduction vitamin.

Sources: It is usually found in some natural oils such as wheat-germ oil, rice-germ oil and in leafy green vegetables. It is also found in meat, egg yolks and fish liver oil but in poor quantity. It is absorbed through intestine and this process is promoted by bile salts. It is mainly stored in adipose tissue.

Physiological role: This vitamin maintains the normal health of the sex organs and ensures the continuation of pregnancy and spermatogenesis in rats, rabbits and other mammals. Therefore, it is also called anti-sterility vitamin or fertility vitamin or reproduction vitamin.

Deficiency of vitamin E result in nerve problem, anemia, weak immunity, male infertility  

Recommended dietary allowance for adults 15 IU 

 

Vitamin K (Phylloquinone or Naphthoquinone)

It is popularly called coagulation vitamin or antihemorrhagic vitamin. Chemically this vitamin is a group of compounds called naphthoquinones.

Sources: All green leafy vegetables, fresh or dry liver, egg and fish meal is good source of this vitamin. Microorganisms like bacteria, molds and yeast are said to be good sources of this vitamin.

Physiological role: This vitamin plays an important role in coagulation of blood as it is necessary for the formation of prothrombin. It is an important factor in the clotting of blood.

Deficiency of vitamin K is haemorrhage

Recommended dietary allowance for adults 122 mcg(men), 138mcg(women)

 

Water soluble vitamins

 

Vitamin B or B complex

Vitamin B complex comprises of the following vitamins

Vitamin B1 (Thiamine)

It is commonly known as antineuritic or antiberiberi or aneurin vitamin

 Sources: Brewer's yeast is the richest source of thiamine. Seed coat or bran of cereal

contain vitamin Bi. Liver, kidney and egg yolk are also rich sources of this vitamin.

Physiological role: This vitamin functions in all cells as the coenzyme cocarboxylase

which is essential for the enzymatic decarboxylation of a-keto acids. Thus, it serves in

the decarboxylation of pyruvate to acetate which in turn, combine with co-enzyme A and enters the kreb's cycle. Hence deficiency of thiamine leads to the accumulation of pyruvic acid and lactic acid in the blood and tissues.

Recommended dietary allowance for adults 1.4mg

Deficiency- Beriberi, cataract, depression.

 

Vitamin B2 (Riboflavin)

It is also known as vitamin G or lactoflavin or ovoflavin. It is widely distributed in nature.

Sources: Liver, milk egg and green leafy vegetables.

Physiological role: Riboflavin plays an important role in the release of food energy

and the assimilation of nutrients. It combines with nucleic acid to form flavoproteins,

essential in cell respiration. It is involved in the cell metabolism of protein, fats, carbohydrates and nucleic acids by forming part of the flavoprotein.

Recommended dietary allowance for adults 1.6mg

Deficiency- lesion of eye, reddened lips, cracks at the corner of mouth

 

Vitamin B3/Nicotinic acid (Nicotinamide or Niacin)

This vitamin is synthesized in the tissues of many organisms from the amino acid tryptophan.

Source: Yeast, liver, peanut, wheat germ and soybean are natural sources

Physiological role: It forms an essential component of NAD and NADP and thus

forms co-enzymes. As a co-enzyme it is important in fermentation and glycolysis.

Recommended dietary allowance for adults 18 mg

Deficiency-Pellagra

 

Vitamin B6 (Pyridoxine)

Three naturally occurring substances pyridoxine, pyridoxal and pyridoxamine form vitamin B. The symbiotic flora of intestine of many animals and ruminants synthesizes pyridoxine.

Source: Yeast, milk, rice, cereals, pulses and meat are good sources of this vitamin

Physiological role: It is closely related to niacin and forms part of an enzyme system for the synthesis of amino acids. It is an important constituent of the enzyme, transaminase, involved in protein metabolism. This vitamin is a dietary essential for many protozoans, bacteria, insects and vertebrates including man. It also plays an important role in brain metabolism.

Recommended dietary allowance for adults 1.3 mg

Deficiency-Dermatitis, kidney stone, muscular convulsions

 

Vitamin B5 (Pantothenic acid)

 It forms part of an enzyme system.

Source: Good source of this vitamin include yeast, milk, liver and egg yolk.

Physiological role: It forms coenzyme A by combining with adenylic acid, phosphate and a sulphydryl group. Coenzyme A is used in Kreb’s cycle in the transfer of acetyl group from pyruvic acid. It is also involved in the formation of acetyl choline.

 Recommended dietary allowance for adults 10 to 15 mg.

Deficiency-Fatigue, impaired co-ordination

 

Vitamin B12 (Cyanocobalamin)

It has got a very complex structure with cobalt, cyanide and amino groups. It occurs in natural water. The symbiotic microorganisms of most animals can synthesize this vitamin

Source: Liver, milk, yolk, fish and meat are good sources of this vitamin.

Physiological role: Cyanocobalamin is a growth factor and anti-pernicious anaemia factor. It is essentially required for normal formation of blood and erythrocyte maturation. It also plays a part in purine metabolism.

Recommended dietary allowance for adults 2.4ug.

Deficiency-pernicious anemia, neurological disorders.

 

Vitamin H (Biotin)/B7/ coenzyme R

Like cyanocobalamin, biotin also occurs in natural waters.

Source: Protein in the egg white, yeast, liver, molasses, tomatoes and milk contain Biotin

Physiological role: it is important for the synthesis of an enzyme which converts pyruvic acid into oxaloacetic acid. It also functions in the deamination of amino acids.

Daily requirement: There is no Recommended dietary allowance for biotin, only suggested adequate intake levels.

Deficiency-fatigue, depression, muscular pain (lactic acidosis-pyruvate converted to lactate, hypoglycaemia.

Vitamin B9 (Folic acid)

This vitamin is found in green leave and hence the name. It is also named as vitamin M because it can prevent a nutritional anaemia in monkeys. It is also known as vitamin Bc because it can prevent nutritional anaemia in chicks. Some intestinal bacteria can synthesize it.

Source: it is found in abundance in liver, kidney, yeast, egg, milk, seeds and mushroom

Physiological role: it is needed for synthesis, repair and methylation of DNA and formation of RBC.

Recommended dietary allowance for adults 400 ug

Deficiency-Anemia

 

Choline

 It is the basic constituent of lecithin and acetyl choline.

Source: liver, kidney, meat, peas and leafy vegetables.

Physiological role: Choline plays a role in fat metabolism and also serves as precursor of acetyl choline which is concerned with synaptic transmission of nerve impulses.

Recommended dietary allowance for adults 550mg/day

Deficiency- muscle damage, liver damage and non-alcoholic fatty liver disease (hepatosteatosis).

Vitamin B8 (Inositol)

It is a derivative of benzene and occurs in plant products as an organic phosphorous substance.

Source: Various types of plant and animal tissues contain inositol.

Physiological role: It acts as an important growth factor. But it is observed that in the presence of inositol, the blood cholesterol level is not increased. This vitamin plays a role in fat metabolism.

Vitamin C (Ascorbic acid)

Source: The main source of this vitamin is citrus fruit, gooseberry tomatoes, potatoes, green leafy vegetables and other fresh fruits and vegetables. Vitamin c is required by primates in their food. All other vertebrates and some invertebrates can synthesize vitamin c from carbohydrates.

Physiological role: It plays an important role in cellular respiration and carbohydrate metabolism and in the conversion of folic acid to folinic acid. It produces and maintains the collagen in the matrix of connective tissues. It helps the body to build resistance against infection from bacteria and the toxic products by such infection. It also helps the absorption of calcium and iron from the intestine. It is involved in tyrosine metabolism. It controls the cholesterol metabolism.

Recommended daily allowance is 75mg

Deficiency- Scurvy

Dietary fibre

This is the natural packing of the plant foods. It can be defined as those parts of the food which are not digested by human enzymes. The principal classes of dietary fibres are cellulose, hemicellulose, lignin, pectin and gums. These are all polysaccharides except lignin. Bran, cabbage carrots, fruits and some leafy vegetables have a relatively high content of dietary fibres. They provide normal bowel movements and serves as a natural laxative. Dietary fibre is partially digested in the large intestine by resident bacterial flora and a small amount of energy is released.

Balanced diet

Body requires a definite amount all nutrients in the diet to maintain normal health. A diet containing a proportionate mixture of these constituents as required by the body is known as balanced diet. The dietary requirement varies with age, sex and physical condition of the body. Thus, in adults, the protein intake should be Igm per kg body weight. Some of it is in the form of animal protein. A normal diet of 3000 Kcal should contain at least 75 gm. of fat. The daily intake of carbohydrate should be commonly in the range of 300 to 500 gms. The minimum requirement of sodium chloride is 1-2 gm daily. Similarly, 0.9 to 1 gm calcium is needed daily. The daily intake of iron should not be less than 12mg. Traces of iodine are to be taken daily. Water is very important for all organisms and man requires a minimum two litres of water per day.