Labdoor analyzed 18 of the best-selling glucosamine supplements in the United States for glucosamine content as well as heavy metal (arsenic, cadmium, lead, mercury) contamination.
Labdoor's analysis found that about 80% of the tested products (15 of 18) recorded glucosamine doses of at least 1500 mg per day, the lowest level at which glucosamine has been found in research studies to improve joint pain and function1. Six products also listed chondroitin and another 14 products listed MSM (methylsulfonylmethane).
With respect to purity, all products passed heavy metal screens. Shellfish is a common source for glucosamine supplements. For people who are allergic to shellfish, note that 6 products are shellfish-free.
Analytical Chemistry Methods: CE (glucosamine); HPLC (chondroitin); GC (MSM); ICP-MS (arsenic, cadmium, lead, mercury).