A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e., vitamers) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrients cannot be synthesized in the organism, either at all or not in sufficient quantities, and therefore must be obtained through the diet. Vitamins are often used as a form of medicine to treat ailments such as colds, or to counteract lifestyle issues such as stress. Contrary to popular belief, vitamins aren't drugs or miracle cures. They are organic compounds that participate in various metabolic functions. Vitamins are often used as a form of medicine to treat ailments such as colds, or to counteract lifestyle issues such as stress. Contrary to popular belief, vitamins aren't drugs or miracle cures. They are organic compounds that participate in various metabolic functions.