Extra Strength Biotin from NOW® delivers 10,000 mcg of this valuable B-vitamin. Biotin is a water-soluble vitamin necessary for normal growth and body function.* Biotin functions as a key regulatory element in gluconeogenesis, fatty acid synthesis and in the metabolism of some amino acids.* Alongside its role in energy production, biotin supports the synthesis of certain proteins.* In addition, biotin promotes healthy immune system function and plays a critical role in skin health.*