Vitamin B5, also known as pantothenic acid, is sometimes included in hair care products and supplements with claims of supporting hair health. There is a scientific basis for its necessity in human nutrition, as it is an essential vitamin involved in the synthesis of coenzyme A, which is important for fatty acid metabolism and overall cellular function. Severe deficiency in Vitamin B5 can lead to symptoms such as fatigue, irritability, numbness, and, rarely, hair loss. However, such deficiencies are exceedingly rare due to the widespread presence of pantothenic acid in foods.

Regarding hair specifically, there is limited direct scientific evidence showing that supplementation with Vitamin B5 significantly improves hair growth or prevents hair loss in people who are not deficient. Most studies on hair and vitamin B5 are either outdated, small-scale, or lack rigorous controls. Some anecdotal and preliminary evidence suggests that topical panthenol (a derivative of Vitamin B5) can improve the appearance and manageability of hair, but this is considered a cosmetic effect rather than a physiological change in hair growth or health.

In summary, while Vitamin B5 is essential for general health and severe deficiency could theoretically impact hair health, there is only weak scientific evidence supporting its supplementation specifically for hair health in the absence of deficiency. Its common inclusion in hair products is based more on its cosmetic benefits than on robust clinical research.