Biotin is one of the B vitamins (found mainly in red meat, nuts, bananas and cooked eggs).
It plays a key role in the production of keratin, which is the major protein found in hair. So you might assume that taking biotin supplements would encourage beard growth.
However, whilst you can correct a biotin deficiency with supplements, most healthy men are already getting enough from their diet and aren’t likely to benefit from extra biotin.
So, although it’s quite safe to take the supplements, more data is needed to prove whether it makes a difference to beard growth or not.