Vitamins are organic compounds which are present in variable, minute quantities in natural foodstuffs and essential for the normal processes of growth and higher forms of the body. Vitamins generally are not synthesized in the body, but must be taken in with the diet. Vitamins do not furnish energy. They act as catalysts for energy transformation and regulation of metabolism. Vitamins were classified according to their solubility in water or fats. Vitamins A, D, E and K are fat soluble; The water-soluble vitamins are the B complex (consisting of vitamin B₁, vitamin B₂, vitamin B₆, vitamin B₁₂, niacin, pantothenic acid, biotin and folic acid) and C vitamins. There are a number of organic compounds related to the vitamins in activity and can be synthesized by man in adequate amounts and therefore are not required in the diet. These substances usually are classified with vitamin-like substances (sometims classified with the B vitamins). They are choline, myoinositol, p-aminobenzoic acid, carnitine, lipoic acid. Vitamin P group (bioflavonoid)that decrease blood capillary fragility is no longer considered to be vitamins.