Consumer Reports tested 16 popular glucosamine-chondroitin supplements, evaluating three samples of each. First the samples were tested to see whether they contained the amount of glucosamine and chondroitin that the label indicated. Testers also conducted a dissolution test, which measures how well tablets and caplets break down in water within an hour. And they tested for heavy metals, such as mercury and lead.
Tests show that none of the supplements contained worrisome levels of lead or other toxic metals. And all of the products contained their labeled amounts of glucosamine. But Nature Made Triple Flex Triple Strength averaged only 65 percent of the labeled amount of chondroitin.
Six others averaged 79 to 87 percent. And of the 16 tested, two did not dissolve sufficiently, indicating that the ingredients might not be fully absorbed in the body. They were the Trigosamine Max Strength and 365 Everyday Value Extra Strength from Whole Foods.
However, nine did meet Consumer Reports' quality criteria. The least expensive is Kirkland Signature Clinical Strength tablets from Costco.
Consumer Reports suggests checking with your doctor before trying joint supplements, particularly if you're taking blood thinners or if you're allergic to shellfish. Glucosamine is often made from shrimp shells, and it can increase the effects of blood thinners.