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Vitamins are naturally occurring organic compounds that are essential to metabolic or other functions in the body. In most cases vitamins cannot be synthesized by the body. They must be supplied in the diet.
While energy supplying nutrients such as carbohydrates, lipids, and proteins undergo extensive modification during metabolism, vitamins are generally used by the body with very minimal changes
Vitamins 0are usually required in only small amounts, but never the less they are essential to life processes. Each vitamin has one or more specific purposes.
Vitamins can be classified as either water soluble or fat soluble. Water soluble vitamins are generally involved in the cellular metabolism of energy supplying nutrients. Fat soluble vitamins often have very specialized functions
Water soluble vitamins usually contain hydrogen attached to electronegative atoms such as oxygen or nitrogen. They easily form hydrogen bonds with water molecules. Water soluble vitamins do not accumulate in the body, so regular supplies are necessary
Examples of water soluble vitamins include:
Vitamin C Vitamin B
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(Thiamine)
Fat soluble vitamins have long nonpolar hydrocarbon chains or rings. These include vitamins A, D, E, F and K. Fat soluble vitamins usually accumulate in tissues and are not leached out quickly. Unlike water soluble vitamins, an excess of a fat soluble vitamin can be just as harmful as a deficiency
Vitamin D

Vitamin K
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Vitamin C is found in many fresh fruits and vegetables. It contains several polar groups, making it very water soluble.
Cooking vegetables in water tends to leach the vitamin from the food. Cooked foods often contain less vitamin C, since it is also easily oxidized and hence destroyed in the cooking process.
Vitamin C is known to aid in healing wounds and helping to prevent bacterial infections. It is involved in the biosynthesis of the protein, collagen, found in connective tissues such as cartilage, ligaments, and tendons
Although massive doses of vitamin C have often been thought to help in the prevention of the common cold, there is no reliable evidence to show that this is true
A deficiency of vitamin C results in a disease known as Scorbutus or scurvy. This condition is characterized by swollen legs, rotting gums, and bloody lesions. It was often common among sailors in the 18 th and 19 th centuries who spent a long time at sea without fresh fruits and vegetables
Vitamin A is also known as retinol. It is commonly found in cod liver oil, green vegetables, and fruit. Carrots indirectly serve as a source of vitamin a since they contain β carotene which the body readily converts to vitamin A
Vitamin A
Vitamin A is fat soluble. It is not readily broken down by cooking.

Vitamin A plays a very important role in aiding in night vision. Retinol is oxidized to retinal, which combines with the protein opsin to form rhodopsin. Rhodopsin is the active agent which converts light signals to electrical impulses that the optic nerve transmits to the brain
Retinol Retinal
A deficiency in vitamin A results in night blindness. A serious deficiency results in a condition known as Xeropthalmia, a severe form of conjunctivitius or blindness.
Vitamin D is commonly found in fish liver oil as well as egg yokes. Unlike other vitamins, the body synthesizes vitamin
D in the skin through the action of ultraviolet light on 7-dehydrochlosterol
Vitamin D
Vitamin D is an important regulator of calcium metabolism. It is involved in the uptake of calcium and phosphate ions from food into the body. It is necessary for the proper formation of bone structures and teeth.
A serious deficiency in vitamin D results in a condition known as Ricketts. It is characterized by bone softening an malformation.
Vitamin D is destroyed by bleaching agents that are often used in the manufacture of purified white flour