Collagen is the most abundant protein in the human body, making up about a third of its protein composition. It is one of the main building blocks of bones, skin, muscles, tendons, and ligaments. Collagen is also found in many other parts of the body, including blood vessels, corneas, and teeth. You can think of it as the "glue" that holds all of these things together. In fact, the word comes from the Greek word "kólla," which means glue.
By supporting the individual building blocks of the body, collagen plays an important role in strengthening the immune system.