Keratin

Keratin is a naturally occurring protein the human body that is partially responsible for hair, nails, and the outer layer of skin. Because it's produced by the human body, it's not naturally occuring in foods. However, a diet rich in amino acids, protein, vitamin A, and Biotin can encourage production and provide support for hair, skin, and nail growth. 

Naturally found in... your skin, hair, and nails (please don't eat these).

Products with Keratin: Keratin Conditioner