Vitamins

Water Soluble Vitamins

Vitamins are essential nutrients found in foods. The requirements are small but they perform specific and vital functions essential for maintaining health. There are two broad types of vitamins classified by the elements in which they dissolve. They are:

(i)

Fat-soluble vitamins — vitamins A, D, E and K — which dissolve in fat before they are absorbed into the blood stream to carry out their functions. Excesses of these vitamins are stored in the liver. Because they are stored, they need not essentially form part of the daily diet.

(ii)

Water-soluble vitamins which dissolve in water and are not stored in the liver; they are flushed out of the body through urine. We need a continuous supply of water-soluble vitamins in our diets. The water-soluble vitamins are the B-complex group and vitamin C. They are easily exhausted or washed away during food storage or preparation. Proper storage and preparation of food can minimize the loss of such vitamins. 

The eight vitamins of the B-Complex group

The water-soluble vitamins, excluding vitamin C, popularly are termed the B-complex vitamins. There are eight of them, namely; B1 (thiamine), B2 (riboflavin), B6 (pyridoxine), niacin (nicotinic acid), B12, folic acid, pantothenic acid, and biotin. The effects of the water-soluble vitamins are obvious in many parts of the body. They act as coenzymes to help the body obtain energy from food. They also are important for normal appetite, good vision, healthy skin, healthy nervous system and red blood cell formation.

Thiamin functions as the coenzyme thiamin pyrophosphate (TPP) in the metabolism of carbohydrate and in conduction of nerve impulses. Thiamin deficiency causes beri-beri, which is frequently seen in parts of the world where polished (white) rice or unenriched white flour are predominantly eaten.

Riboflavin is helpful in maintaining good vision and healthy hair, skin and nails, and it is necessary for normal cell growth. Riboflavin deficiency causes a condition known as ariboflavinosis, which is marked by cheilosis (cracks at the corners of the mouth), oily scaling of the skin, and a red, sore tongue. In addition, cataracts may occur more frequently with riboflavin deficiency.

Niacin exists in two forms, nicotinic acid and nicotinamide. Both forms are readily absorbed from the stomach and the small intestine. Niacin is stored in small amounts in the liver and transported to tissues, where it is converted to coenzyme forms. Any excess is excreted in urine. Niacin is one of the most stable of the B vitamins.

Vitamin B12’s primary functions are in the formation of red blood cells and the maintenence of a healthy nervous system. B12 is necessary for the rapid synthesis of DNA during cell division. If B12 deficiency occurs, DNA production is disrupted and abnormal cells called megaloblasts occur. This results in anaemia.

Folic acid helps the body make healthy new cells. Everyone needs folic acid. For women who may get pregnant, it is really important. Pantothenic acid is stable in moist heat. Dietary deficiency occurs in conjunction with other B-vitamin deficiencies. In studies, experimentally induced deficiency in humans has resulted in headache, fatigue, impaired muscle coordination, abdominal cramps, and vomiting.

Biotin is the most stable of B vitamins. Biotin is synthesized by bacteria in the large intestine, but its absorption is questionable. Biotincontaining coenzymes participate in key reactions that produce energy from carbohydrate and synthesize fatty acids and protein.

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