Our celebrity-loved collagen powder is Types I and III. Type I is the most prevalent type of collagen in the body. This is the type of collagen supplement you’re probably thinking about if you’re interested in preserving the levels of collagen in your skin, hair or nails. But Type I collagen isn’t just a beauty-related substance. It’s also a major component of the tendons, organs and bones. Type III is generally found in reticular fibers, such as in the bone marrow. It’s usually found alongside Type I collagen in the body.