Question: what is the best supplement to promote hair growth?
Answer: Vitamin A. All cells need vitamin A for growth. ...  B-Vitamins. One of the best known vitamins for hair growth is a B-vitamin called biotin. ...  Vitamin C. Free radical damage can block growth and cause your hair to age. ...  Vitamin D. ...  Vitamin E. ...  Iron. ...  Zinc. ...  Protein.