What are Vitamins

Vitamins are generally synthesized  by plants and found  in animals as a result of food intake and  also because of synthesis of some of the vitamins by gut microorganisms. All  living beings not necessarily need the same number or kind of vitamins as some of these may be produced by the organism concerned. For instance, rat can synthesize vitanii~~  C but a guinea pig or man  cannot. We, human beings,  in  fact can synthesize only two vitamins -  vitamin D and niacin.