The B vitamins are eight water-soluble vitamins that play important roles in cell metabolism. Historically, the B vitamins were once thought to be a single vitamin, referred to as vitamin B (much like how people refer to vitamin C or vitamin D). Later research showed that they are chemically distinct vitamins that often coexist in the same foods. Supplements containing all eight are generally referred to as a vitamin B complex. Individual B vitamin supplements are referred to by the specific name of each vitamin (e.g. B1, B2, B3 etc ).
List of B vitamins
- Vitamin B1 (thiamine)
- Vitamin B2 (riboflavin)
- Vitamin B3 (niacin, includes nicotinic acid and nicotinamide)
- Vitamin B5 (pantothenic acid)
- Vitamin B6 (pyridoxine, pyridoxal, and pyridoxamine)
- Vitamin B7 (biotin), also known as vitamin H
- Vitamin B9 (folic acid), also, vitamin M
- Vitamin B12 (various cobalamins; commonly cyanocobalamin in vitamin supplements)
Former or unclassified vitamins
- Vitamin B4 (adenine, DNA metabolite) is no longer classified as a vitamin because it is synthesized by the human body
- Vitamin B8 (myo-inositol, adenylic acid, DNA metabolite) is no longer classified as a vitamin because it is synthesized by the human body
Different B vitamins come from different natural sources, such as potatoes, bananas, lentils, chile peppers, tempeh, liver oil, liver, turkey, tuna, Nutritional yeast (or brewer's yeast) and molasses. Marmite and Vegemite bill themselves as "one of the world's richest known sources of vitamin B". As might be expected, due to its high content of brewer's yeast, beer is a source of B vitamins, although this may be less true for filtered beers and the alcohol in beer impairs the body's ability to activate vitamins.
The B-12 vitamin is of note because it is not available from plant products, making B-12 deficiency a concern for vegans. Manufacturers of plant-based foods will sometimes report B-12 content, leading to confusion about what sources yield B-12. The confusion arises because the standard US Pharmacopeia (USP) method for measuring the B-12 content does not measure the B-12 directly. Instead, it measures a bacterial response to the food. Chemical variants of the B-12 vitamin found in plant sources are active for bacteria, but cannot be used by the human body. This same phenomenon can cause significant over-reporting of B-12 content in other types of foods as well.
Vitamin B may also be delivered by injection to reverse deficiencies.