Collagen Peptides is a type of protein. In fact, it’s the most abundant structural protein in animals. A structural protein is one that makes up the structure or framework of your cells and tissues. There are 28 known types of collagen, with type I collagen accounting for 90% of the collagen in the human body. Collagen is composed mainly of the amino acids glycine, proline, and hydroxyproline. These amino acids form three strands, which make up the triple-helix structure characteristic of collagen