Folic acid, also known as folate, is one of the B-complex vitamins, all of which play a role in keeping your hair and skin healthy. Hair loss is caused by a variety of factors, like aging, nutrient deficiencies, underlying health conditions or taking certain medications or treatments. There is no evidence to support the use of folic acid for hair loss in humans, so check with your doctor before adding supplements of this vitamin to your daily routine.
A classic animal study published in Veterinary Record noted that a calf with hair loss and signs of folic acid deficiency showed improvement in hair growth when given supplemental folic acid.
Folic acid deficiency could cause hair loss and slow regrowth of hair because it limits the flow of oxygen and blood to the cells responsible for hair growth. Thus, taking folic acid to eliminate the deficiency might help with hair loss, though this has never been demonstrated in humans.
If you're losing hair due to taking rheumatoid arthritis medications, folic acid may help limit this hair loss, but it isn't likely to cause your hair to regrow, according to the Arthritis Foundation.