What is msm? Methylsulfonylmethane (msm) is a natural sulfur compound that helps support healthy joint function. How does it work? Msm supports organ and joint function by donating sulfur for maintenance of healthy connective tissue. Msm helps keep skin, hair and nails healthy by donating sulfur for production of keratin, a fibrous protein benefits of pure naturals msm-maintains healthy connective tissue-supports joint health-exceptional quality at an extraordinary value. Dietary supplement quality guaranteed: gmp certified products-best naturals' commitment to the highest standards of product quality and efficacy are evident throughout our entire product development process. As a continued measure of quality, all ingredient suppliers are required to provide a certificate of analysis for each raw material they supply, and each ingredient is verified for purity through in-house or independent laboratory testing. To reduce any chance of physical, chemical, or microbiological contaminants, pure naturals has implemented a strict set of fda compliant manufacturing procedures to ensure product integrity, including daily inspections of all storage, blending, and production areas.