Most human studies have used glucosamine sulfate. This is because the company that paid for the research developed this form. Glucosamine HCL has not been evaluated as extensively, but clinical experience from a variety of health practitioners indicates that glucosamine HCL works just as well. Many health practitioners recommend trying one, and if that does not work, trying the other. MSM is a biologically active form of the mineral sulfur.
Sulfur is the fourth most plentiful mineral in the body and is found in every cell of the body.
Sulfur plays a particularly important role in tissue structure. MSM is naturally present in foods and the human body. MSM has been used by veterinarians for more than 15 years, and use by humans goes back some 20 years. These compounds are returned by rainwater to the earth, where they are absorbed by plants. MSM contributes to healthy joints because, as a form of sulfur, it adds to the benefits of glucosamine.