Ever since my hair fell out, I've been taking Biotin daily; it's supposed to help your hair and nails grow strong! When I was getting induced with the Taxol part of chemotherapy, I was warned of the side effect - my fingernails and toenails could turn black and fall off - so not hot!! I kept on with my Biotin, and thank God, nothing happened to my nails. The Nature's Bounty brand was given to me from my beautiful friend Jaime, I figure if she likes it, then it's good enough for me!