Biotin, also known as B7 or H, is a water-soluble vitamin for hair loss. Biotin has been shown to promote hair growth, thicken the hair strand, and prevent hair loss. If your diet lacks B vitamins like Biotin, it may result in hair loss. Hair loss vitamins such as Biotin, Niacin (Vitamin B3) and Vitamin C, and minerals for hair loss such as Zinc and Iron, provide essential hair nutrients to nourish healthy and longer hair. Eating enough of these key hair growth vitamins can help prevent hair loss in both men and women.