Once thought to be a single vitamin, B complex is now classified as 12 related water-soluble compounds. Four are synthesized by the body, but the remaining eight are not, and function as co-enzymes in the body in achieving optimum health.
You're probably familiar with thiamine, riboflavin and thiamine, as these words often appear as added nutrients on the ingredient labels of processed foods. Respectively, they are B complex vitamins B1, B2 and B3 and are all essential to metabolism. The benefits of the remaining 12 B complex vitamins, B5, B6, B7, B9 and B12, range from a healthy heart and brain, to the production and absorption of other nutrients needed to maintain strong bones, teeth, nails and hair, and to produce energy in the body. So what happened to vitamins B4 and B8?
In short, nutrition is not a perfect science. Vitamin B4 technically exists as adenine, which is one of the five nitrogenous bases that helps make up the code in DNA and RNA – but it's rarely referred to as B4. Vitamin B8 and B9 appear interchangeable in the literature and both refer to folic acid or folate, needed for cell replication and growth.
Natural sources high in B complex vitamins include meat and dairy products, which is why strict vegans and vegetarians are often encouraged to supplement their whole food diets with a complete B complex supplement. But meat and milk lovers don't be fooled! Nutritionists say most people, including you, don't get enough B complex in diet and should consider daily supplementation.