Biotin is found in egg yolks, brewer's yeast, bananas, lentils, cauliflower, and salmon. This B vitamin strengthens skin, hair, and nails. (A deficiency is extremely rare because bacteria in your intestines make all the biotin you need.) A deficit can lead to hair loss or dermatitis (itchy, scaly skin). Some people beleive that biotin supplements strengthen their brittle nails, but studies have not proven that it's beneficial for anyone who's not deficient in the vitamin.
