What doses of the B vitamins are needed?

The role of the B vitamins is not entirely clear. For some vitamins, such as biotin and vitamin B12, it seems that unless one is truly deficient in the particular vitamin, supplementation is not going to help.

Whether that is true for all the B vitamins is not clear. It certainly may be that some B vitamins are beneficial for hair growth even if the patient has normal levels. In patients with excessive shedding (telogen effluvium) in which an underlying cause can not be found, I often recommend 50-100 mg of vitamin B5 (pantothenic acid) and the same dose of B6.

Administration of vitamin B5 and vitamin B6 appear to have some benefits in human and animal studies.