Type I collagen is the most abundant collagen in the human body, making up around 90% of the bodys total collagen. It forms large, eosinophilic fibers known as collagen fibers and is present in scar tissue, tendons, ligaments, the endomysium of myofibrils, the organic part of bone, the dermis, the dentin, and organ capsules. Type I collagen is a fibrillar type collagen and is the key structural component of skin, bones, tendons, and ligaments. It is also used in supplements to support healthy skin, hair, and nails, and has been used for osteoarthritis, scleroderma, and other conditions, although there is no good scientific evidence to support these uses. Type I collagen is sourced from cows, pigs, fish, and other animals, and is made in the human body with amino acids.