Biotin has many benefits for your body.
Its primary role is to help turn the food you eat into energy. It is also required by your body to produce keratin, which is a type of protein found in hair, skin, and nails
Many foods contain biotin, meaning that deficiency is rare in healthy people who eat a balanced diet (2Trusted Source).
Although rare, biotin deficiency can cause skin rashes, brittle nails, as well as hair thinning and loss. This is due to the vitamin’s role in the production of keratin
As such, biotin supplements and biotin-added hair products are commonly advertised to support healthy hair growth or promote thicker, voluminous hair.
Despite these claims, though, there’s limited evidence to suggest that supplementing with biotin or lathering it through your hair promotes hair growth in non-deficient people.
In an older 2012 study, women with self-perceived thinning hair were randomised to receive either a multi-ingredient hair growth supplement that contained biotin or a placebo for 6 months (4Trusted Source).
Those who received the hair growth supplement reported a visible increase in overall hair volume, scalp coverage, and thickness after the treatment period. Meanwhile, there were no significant changes in the placebo group.
However, because the hair growth supplement contained multiple ingredients — including zinc and iron, which are also necessary for hair growth — it’s not possible to attribute the study’s findings to biotin alone.
Further, the study was small, and it’s possible that the participants were deficient in one or more nutrients present in the supplement that affect hair health. During the study period, any such deficiency could have been corrected, resulting in hair growth.
In a different study, researchers found that children who experienced improved hair growth or quality after taking biotin supplements all had an underlying condition that caused a biotin deficiency
Outside of these studies, there is no strong evidence to support taking biotin supplements or using biotin-added hair products to promote hair growth