Background Information
B-complex vitamin products provide several or all of the B-vitamins, but unlike multivitamins they do not contain other nutrients. Often, the B-vitamins are included at relatively high potencies, and the product may have names like "B-complex 100" or "B-complex 50," hinting at their composition of 100 mg or 50 mg of each of several of the B-vitamins. Selection of a B-complex mixture rather than a multivitamin or multivitamin with minerals presupposes a need for or benefit from the B-vitamins but not from other nutrients. There is little to no evidence that such a supposition is correct.

A rationale frequently offered for use of a B-complex mixture is that these vitamins are necessary for energy metabolism. While it is generally true that several of B-vitamins are involved in energy production, some are not. Vitamin B-6 is also involved in metabolism of amino acids and many other substances. Folic acid and vitamin B-12 are involved in production of DNA and RNA, among other actions.

 Effects on Health
Marginal or deficient intakes of each of the B-vitamins are not equally likely to occur. The RDAs of vitamins B-1, B-2, and B-6 are similar (a little less than 2 mg per day). The RDA for niacin is much more, nearly 20 mg/day, and that for B-12 is much less, only 2 mcg/day. There is no rationale for taking all the B-vitamins in equal amounts.

 Supplement Range
Obtain B-vitamins from a wide variety of foods and a multivitamin with minerals.