Methylsulphonylmethane (MSM) is a naturally occurring source of sulphur, one of the major building blocks of glycosaminoglycan's. Glycosaminoglycan's are key structural components in cartilage. MSM powder is ideal for those individuals who find it difficult to swallow capsules or tablets. Methylsulphonylmethane (MSM) is a naturally occurring source of sulphur, one of the major building blocks of glycosaminoglycan's. Glycosaminoglycan's are key structural components in cartilage. MSM powder is ideal for those individuals who find it difficult to swallow capsules or tablets.