The company below includes Molybedenum in their product to undo the effects of heavy-metal poisoning,(meaning mercury poisoning). That is crazy. I would recommend you take only vegetarian glucosamine which should be mercury free. All chondroitin is animal derived but should be free of mercury.
Pure Essentials® "Ultra Bone Repair"
"Arthritis and osteoarthritis" joint repair formula, with Glucosamine and Chondroitin Sulfate
** Molybdenum
Because glucosamine and chondroitin are sea shell and animal derived, Molybdenum is included in Bone Repair as a heavy-metal binder. It also enhances bodily processing of common environmental toxic stresses such as aldehydes,