Some products contain both chrondroitin and glucosamine as a "nutraceutical" intended to improve cartilage condition. Chrondroitin and glucosamine play major roles in maintaining the integrity of joint structure and fluids. MSM (methyl sulfonylmethane) has been used as a source of dietary sulfer, but claims for anti-inflammatory effects are hard to verify. All of these compounds have been purported to improve joint health, and testimonials abound, but supporting research in horses is very limited. I know of nothing to suggest that any of these products is harmful, so they may be used according to manufacturer instructions without undue concern.