Collagen is a natural protein found in the connective tissue of the skin (where it accounts for 70% of its content), as well as in the organs, muscles, bone and cartilage. In fact, there are more than 25 different types of collagen in our bodies. In the skin, it adds suppleness, plumpness, flexibility and spring, and, together with elastin, adds texture and structure. However, as skin ages or is exposed to sun damage, its collagen content is reduced, making skin progressively drier, thinner, flatter, less flexible and more wrinkle-prone. Since animal-derived and plant- derived pseudo-collagen also retains many times its own weight in water, these substitutes are used as conditioning, hydrating and suppleness-boosting ingredients in anti-aging products.

Source: Handbook Of Natural Ingredients - Anthony C. Dweck