MSM is a source of sulphur. It can help boost the immune system and help eliminate parasites. It also helps ease constipation. It is recommended to help decrease fibromyalgia symptoms. MSM doesn't chelate mercury, however if someone is very sulphur deficient, then the body might break down chelating agents(ALA, DMSA, etc.) to use them as a source of sulphur rather than let them chelate mercury.