Collagen is the most plentiful protein in your body, and it’s a major part of your tendons, skin, bones, teeth, muscles and ligaments. Collagen gives your skin strength and resilience. It helps the cartilage in your joints remain supple. It provides structure to your arteries, keeping them strong and flexible. It gives your bones structure, too, by acting as ‘reinforcing rods’. Collagen is an amazing construction material.