Keratin is a family of structural proteins, renowned for its tough, insoluble nature. It is the principal component of the outermost layer of human skin, hair, and nails, as well as the feathers, hooves, and horns of animals. Its unique composition, rich in sulfur-containing amino acids like cysteine, allows for the formation of strong disulfide bonds, which contribute significantly to its stability and resistance to degradation. This essential protein plays a crucial role in maintaining the integrity and protective barrier function of various tissues. In the skin, keratinocytes produce keratin that forms a robust shield against environmental damage, pathogens, and water loss. For hair, keratin provides its strength, elasticity, and shape, while in nails, it forms the hard plate that protects the fingertips and toes. Keratin supplements, often derived from animal sources, are used to support the body's natural keratin production, aiming to improve the health, appearance, and strength of hair, skin, and nails. It is frequently hydrolyzed into smaller peptides for better absorption and bioavailability when taken orally, or applied topically to enhance external structures.

