It will make your skin look dewy and fresh, your bones and nails strong, and your joints pain-free. These are the claims made by the countless manufacturers of collagen supplements that come in the form of powders, pills and creams. For that reason, it’s no surprise that collagen has become a widely sought-after ingredient in the wellness and beauty communities. But collagen’s efficacy is still pretty up in the air.

Frustrated? Here’s what we know.