NOW® Solutions Clinically Advanced Hair, Skin and Nail Formula contains the exciting new ingredient Cynatine® HNS, a specialized form of solubilized, bioavailable keratin that’s been clinically tested and proven to support optimal hair strength, brightness and thickness. Cynatine® also supports strong nails as well as skin elasticity and firmness.* Keratin is the name given to a family of fibrous proteins that comprise the primary structural component of the skin’s outer layer, or the epidermis. Keratin is also an important component of hair and nails. Like all proteins, keratin is made up of various amino acids, and variations in this amino acid composition can make keratin soft and pliable as found in the skin and hair, or rigid and inflexible as found in nails.