Multivitamin tablets on top of an enlarged list of the ingredients. Multivitamins usually contain all thirteen major vitamins-vitamins A, C, D, E, K, and the eight B-complexes. Vitamins are organic compounds that the body needs in small amounts to maintain good health. However, the body is either unable to make or produce a big enough amount for itself. People who may need increased vitamin intake include the very old and young, pregnant women, and those on a poor or limited diet.