MSM (methylsulfonylmethane) is made by oxidizing a chemical called DMSO (dimethyl sulfoxide) with hydrogen peroxide, typically using a metal-based catalyst and moderate heat. This industrial process mirrors, in simplified form, what happens naturally in Earth’s atmosphere. Understanding both pathways helps explain why MSM quality varies between manufacturers and why purification matters as much as the reaction itself.
Where the Raw Materials Come From
The starting material for MSM is DMSO, and DMSO itself comes from an unexpected place: trees. During the paper pulping process, lignin (the compound that gives wood its rigidity) reacts with molten sulfur in an alkaline solution. This reaction strips two methyl groups from the lignin and transfers them to sulfur, creating dimethyl sulfide, or DMS. That DMS is then oxidized with nitrogen dioxide to produce DMSO, the direct precursor to MSM.
So the chain runs: wood pulp lignin → DMS → DMSO → MSM. Each step adds oxygen to the sulfur atom, progressively oxidizing it. By the time you reach MSM, the sulfur is fully oxidized, making the molecule stable and odorless, unlike its smelly precursors.
The Industrial Synthesis Reaction
To convert DMSO into MSM, manufacturers combine DMSO with a 30% hydrogen peroxide solution. Hydrogen peroxide donates an oxygen atom to the sulfur in DMSO, turning it into methylsulfonylmethane. A catalyst, sodium tungstate, speeds up the reaction without being consumed by it.
The reaction runs in a semi-batch process, meaning hydrogen peroxide is fed in gradually rather than dumped in all at once. Research into optimizing this process found that the best results come at a jacket temperature of 64 to 68°C (roughly 147 to 154°F) with a peroxide feeding rate of 5 to 7 milliliters per minute. These controlled conditions matter because the oxidation reaction generates heat. Adding the peroxide too fast or running the temperature too high creates safety risks and can reduce the purity of the final product.
The result of this reaction is crude MSM dissolved in water, still containing leftover hydrogen peroxide, residual catalyst, and various byproducts. That’s where purification becomes critical.
Purification: Distillation vs. Crystallization
There are two main ways to isolate pure MSM from the reaction mixture, and they produce meaningfully different results.
Crystallization is the cheaper, more common method. The MSM solution is cooled until MSM crystals form and can be filtered out. The problem is that as the crystals form, small pockets (called occlusions) can develop inside them, trapping contaminants like heavy metals, residual water, and reaction byproducts within the crystal structure. These impurities aren’t sitting on the surface where they could be washed off. They’re locked inside.
Distillation takes a different approach, using heat to separate MSM from everything else based on boiling point differences. Pure MSM boils at 478°F (248°C), a temperature distinct enough from water and common contaminants to allow clean separation. A four-stage distillation process can remove benzene, heptane, phenol, mercury, arsenic, cadmium, and lead from the final product. The tradeoff is cost: distillation is energy-intensive and significantly more expensive than crystallization, which is why most MSM on the market uses the crystallization method.
Pure MSM is a white, crystalline powder that melts at approximately 109°C (228°F). Its chemical formula is C₂H₆O₂S, with a molecular weight of 94.13. About 34% of its weight is sulfur, which is the primary reason people take it as a supplement.
How MSM Forms in Nature
The industrial process is actually a shortcut version of a cycle that happens constantly in the ocean and atmosphere. It starts with phytoplankton.
Certain species of marine algae produce a compound called DMSP inside their cells, where it helps maintain osmotic balance for growth. The concentration varies dramatically between species. When these phytoplankton die or get eaten by zooplankton, DMSP spills into the surrounding water and is enzymatically broken down into DMS and acrylic acid.
DMS is volatile and doesn’t last long in seawater, with a lifetime of roughly one day. Some of it gets broken down by microbes or sunlight, but a portion escapes into the atmosphere through air-sea gas exchange. Once airborne, DMS reacts with ozone and other oxidants in a series of steps, eventually forming DMSO and then MSM. This atmospheric MSM dissolves in rainwater and returns to the ground, where it enters soil and plants. That natural sulfur cycle is one reason sulfur-containing compounds show up in fruits, vegetables, and grains, though in very small quantities compared to supplement doses.
Regulatory Status and Quality Markers
MSM produced for human consumption in the United States holds Generally Recognized as Safe (GRAS) status with the FDA. The GRAS designation applies to specific manufacturing procedures, not to MSM as a generic compound, which means quality depends heavily on who made it and how.
Some manufacturers add amorphous silicon dioxide at levels up to 0.5% as a flow agent to prevent caking. This is food-grade material, though it can introduce trace amounts of aluminum depending on the silicon dioxide source. For most consumers this is negligible, but it illustrates why the full manufacturing chain, from raw materials through purification to final additives, determines what ends up in the finished supplement.
If you’re evaluating MSM products, the purification method is the most meaningful quality differentiator. Distilled MSM costs more but carries fewer impurity risks. Crystallized MSM is adequate for most uses, but purity can vary between batches and manufacturers. Some brands publish certificates of analysis showing heavy metal testing results, which gives you a concrete way to compare.