Their studies revealed concern surrounding some crab and shrimp sources of glucosamine and chondroitin being contaminated with lead.
Now something that we take three times a day should not have lead in it! As much as I am not a fan of Costco, their Kirkland brand passed with flying colors.
Remember that the FDA does not regulate supplements in America so if you want your natural substance to work you need to shop smart. Aside from the prescription pharmaceutical grade products that I work with, I have found Twinlab, Jarrow, and Enzymatic Therapy to all be trusted widely available brands that have also passed this test at Consumer Labs. (Just my honest opinion with no strings attached!)
Many chondroitin products do not contain nearly the amount of chondroitin that they purport on the label.
If glucosamine causes digestive upset you should take it in divided doses. Everyone with arthritis should most likely be taking fish oil as an anti-inflammatory measure, and I will write on herbal medicine for arthritis in an upcoming article. For severe arthritis, I typically prescribe 500mg of glucosamine 3 times daily. After symptoms abait this may be reduced to a maintenence dose for economic purposes. I pretty good study found that glucosamine was effective for 80% of patients after about three weeks of use. If you have used the product for three months consistently, and have not noticed any benefits, then you may need to consider that glucosamine or chondroitin may not be helpful for your particular arthritis.