Natural Factors Biotin 10,000 mcg is a one-a-day vegetarian-friendly supplement that promotes healthy nails as well as prevents and improves splitting and brittle fingernail health. Biotin 10,000 mcg also increases the health of skin, strengthens and promotes thicker hair. This essential B vitamin helps the body metabolize carbohydrates, fats, and proteins for the maintenance of good health. Biotin is also available in 1000 mcg and 5000 mcg vegetarian capsules.