Glucosamine

Glucosamine is a natural component of cartilage and one of its main building blocks. It's used to support cartilage and joint mobility, often with chondroitin and MSM.

The usual dose is 1,500 mg a day (glucosamine sulfate is the best-studied form) for at least 2–3 months. It's often sourced from shellfish, so choose a vegetarian form if you have a seafood allergy. If you have diabetes, check with your doctor.