Collagen is primarily composed of three amino acids that are repeated in a characteristic sequence to form its fibrillar structure. These three amino acids are: Glycine: Glycine makes up about a third of the amino acids in collagen. It is the smallest amino acid and allows for the close packing of collagen molecules. Proline: Proline also plays an important role in the structure of collagen by contributing to its three-dimensional shape and stabilizing the collagen fibrils. Hydroxyproline: Hydroxyproline is a modified form of proline and is essential for collagen formation as it contributes to collagen's stability and strength. These three amino acids occur in a specific order, resulting in a unique structure that characterizes collagen. The repeating sequence of these amino acids forms a triple helix structure and is the basis for collagen's strength and elasticity. There are up to 28 different types of collagen. The most common and well-known are collagen type I, type II and type III. Type I collagen: is the most common in the body and is found primarily in skin, bones and tendons and makes up approximately 90% of the body's collagen. Type II collagen: is found in cartilage. Type III collagen: is found in blood vessels and other organs. You can see more about what specific functions they have in our blog post which collagen is best in skincare.