Collagen peptides are small pieces of protein from animal collagen that are made by breaking down whole collagen proteins into smaller pieces. Collagen is one of the materials that make up cartilage, bone, and skin. When taken by mouth, collagen peptides seem to build up in the skin and cartilage, which might help improve some skin and joint conditions. Collagen peptides are used for aging skin and osteoarthritis, and they are also used for osteoporosis, brittle nails, muscle strength, and many other purposes, but there is no good scientific evidence to support most of these uses. However, research into the benefits of collagen peptides is ongoing, and many health experts believe taking a collagen supplement may be beneficial in several ways, including better skin health and appearance, reduced joint pain, improved brain and gut health, healthier hair and nails, increased metabolism, and weight loss. Studies show that taking collagen peptides may be helpful in treating and preventing osteoporosis. Collagen peptides are generally safe and well-tolerated, but some people may experience heartburn or feel uncomfortably full after taking a collagen supplement.