BioSil from Natural Factors is specifically formulated to help nourish the body's three beauty proteins: collagen, keratin and elastin. Silicon is a trace mineral required for healthy connective tissue, bone, skin, hair and nails, because it is essential for the formation of collagen and it regulates calcium deposition in bones. Dietary sources of silicon such as those found in food, horsetail and colloidal gel (silica) products are poorly absorbed because of their insoluble, polymerized forms. For optimal absorption to occur, dietary silicon must be first converted to orthosilicic acid (monomeric silicic acid), the bioavailable form found in BioSil. Gluten free.