Collagen is a protein responsible for healthy joints and skin elasticity, or stretchiness. It’s in your bones, muscles, and blood, comprising three quarters of your skin and a third of the protein in your body.

As you age, your existing collagen breaks down, and it gets harder for your body to produce more. As a result, many people turn to collagen supplements. These supplements are usually powders, though there are also capsules and liquid supplements available.

Collagen is also produced naturally in the body by combining amino acids, the building blocks of proteins found in food.