MSM (Methylsulfonylmethane): What It Is and How It Works
MSM is one of the most popular ingredients in supplements for joints and recovery. It is advertised as "organic sulfur," but what is actually known about this molecule? The editorial team explains what methylsulfonylmethane is, how it behaves in the body, and which mechanisms of action are supported by evidence.
What MSM is
Methylsulfonylmethane, or dimethyl sulfone (MSM), is a simple organic sulfur compound with the formula (CH₃)₂SO₂. At room temperature it is a white crystalline powder with no pronounced odor, highly soluble in water. The molecule consists of a sulfur atom, two oxygen atoms, and two methyl groups.
MSM is a product of the oxidation of dimethyl sulfoxide (DMSO), a solvent well known in medicine and chemistry. In fact, interest in MSM arose precisely from research on DMSO: scientists noticed that part of DMSO in the body is converted into dimethyl sulfone and began studying it as a separate substance without the characteristic garlic odor of DMSO.
In nature, MSM is present in small amounts in some plants, milk, coffee, tea, and other products, as well as in human plasma and urine. However, these amounts are very small, so supplements are produced synthetically, most often by oxidizing DMSO with hydrogen peroxide followed by purification (distillation or crystallization).
By mass, sulfur makes up approximately one third of the MSM molecule (about 34%). That is why it is often positioned as a "source of organic sulfur," although in a real diet the main source of sulfur remains proteins with methionine and cysteine.
How MSM behaves in the body
MSM is a small water-soluble molecule that is quickly absorbed in the gastrointestinal tract. In a study with labeled sulfur (Magnuson et al., 2007), the substance quickly appeared in the blood of rats, was distributed among tissues, and was excreted predominantly in the urine, with no signs of significant accumulation.
In humans, MSM is also detected in the blood and urine after intake, and in some studies even in cerebrospinal fluid and the brain, which indicates the ability to cross histohematic barriers. The clinical significance of this fact has not yet been established.
Part of the sulfur from MSM, according to animal data, may be incorporated into sulfur-containing amino acids. However, how important this pathway is for a human with sufficient protein intake is unknown. Therefore the claim "MSM covers a sulfur deficiency" should be treated with caution.
Pharmacokinetic data in humans are quite modest, and standardized parameters (half-life, bioavailability) are not given in guidelines. That is precisely why the intake regimens in studies are usually simple: one or two doses a day for several weeks.
Mechanisms of action: what is known
The review by Butawan, Benjamin, and Bloomer (2017) summarized three main directions used to explain the effects of MSM. The first is anti-inflammatory: in cell models, MSM suppressed the activation of the transcription factor NF-κB, which regulates the expression of pro-inflammatory cytokines and enzymes.
The second direction is antioxidant. Studies have reported changes in markers of oxidative stress and glutathione status with MSM. The mechanism is probably indirect: the molecule itself is not a powerful "trap" for free radicals, but it may influence the regulation of the body's own antioxidant systems.
The third direction is participation in sulfur metabolism as a "building block" for the synthesis of sulfur-containing connective tissue compounds. This is the most popular explanation in marketing, but it is the least proven by direct human studies.
Most mechanistic data have been obtained in vitro or in animals, at doses that cannot always be compared with human ones. Therefore the mechanisms should be regarded as hypotheses explaining the observed clinical results rather than as a proven chain of events.
What MSM is used for
The most research on MSM concerns knee osteoarthritis. In a pilot RCT by Kim and co-authors (2006), 6 g of MSM per day for 12 weeks reduced pain and improved function compared with placebo; Debbi and co-authors (2011) obtained similar results. The effect was moderate, and the studies were small.
In the sports context, MSM has been studied as a means of recovery after exercise: muscle pain, markers of muscle damage, and oxidative stress were assessed. The results are heterogeneous, and we examine them in more detail in a separate article on the evidence base.
MSM has also been studied in seasonal allergic rhinitis, in dermatology (often in combinations with other substances), and as a component of products for hair and nails. These directions have an even weaker evidence base.
The table below summarizes the main areas of application with the editorial team's assessment of the quality of evidence.
| Area | What was studied | Assessment of evidence |
|---|---|---|
| Knee osteoarthritis | Pain, function (WOMAC) | Several small RCTs, moderate effect |
| Recovery after exercise | Pain, damage markers, oxidative stress | Small studies, heterogeneous results |
| Allergic rhinitis | Symptoms | Isolated studies |
| Skin, hair, nails | Cosmetic indicators | Weak, often combinations |
Safety and regulatory status
MSM is considered a substance with low toxicity. In studies on rats (Horváth et al., 2002; Magnuson et al., 2007), even very high doses did not cause serious toxic or teratogenic effects. In clinical work in humans, side effects were rare and mild.
Most often, digestive complaints (bloating, discomfort, loose stools), headache, and sometimes skin reactions are described. They usually resolve after reducing the dose or discontinuing the supplement.
In the US, a particular commercial MSM product received GRAS status ("generally recognized as safe") on the basis of data submitted to the FDA. However, this status concerns use as an ingredient in food products and does not mean confirmation of therapeutic properties.
There is insufficient data on pregnancy, breastfeeding, and prolonged intake beyond a few months in humans. People with chronic diseases and those taking anticoagulants or other ongoing medications should discuss intake with a doctor.
- Low acute toxicity in animals.
- Mild and infrequent side effects in human studies.
- Limited data on special population groups.
Editorial conclusions
MSM is a simple sulfur-containing molecule that is quickly absorbed and excreted from the body. Its effects are associated with anti-inflammatory action via NF-κB, an influence on antioxidant balance, and sulfur metabolism.
The best-studied application is pain in knee osteoarthritis, where small RCTs have shown moderate benefit. Data on sports recovery are encouraging but ambiguous.
The safety profile of MSM is favorable, but it is not a medicinal product and does not replace the diagnosis and treatment of joint diseases.
Our articles "The Benefits of MSM for Athletes: The Evidence Base," "How to Take MSM," and "Side Effects of MSM" will help continue the topic.
References
- Butawan M, Benjamin RL, Bloomer RJ. Methylsulfonylmethane: applications and safety of a novel dietary supplement. Nutrients. 2017;9(3):290.
- Magnuson BA, Appleton J, Ames GB. Pharmacokinetics and distribution of [35S]methylsulfonylmethane following oral administration to rats. J Agric Food Chem. 2007;55(3):1033–1038.
- Kim LS, Axelrod LJ, Howard P, et al. Efficacy of methylsulfonylmethane (MSM) in osteoarthritis pain of the knee: a pilot clinical trial. Osteoarthritis Cartilage. 2006;14(3):286–294.
- Debbi EM, Agar G, Fichman G, et al. Efficacy of methylsulfonylmethane supplementation on osteoarthritis of the knee: a randomized controlled study. BMC Complement Altern Med. 2011;11:50.
- Horváth K, Noker PE, Somfai-Relle S, et al. Toxicity of methylsulfonylmethane in rats. Food Chem Toxicol. 2002;40(10):1459–1462.
- Magnuson BA, Appleton J, Ryan B, Matulka RA. Oral developmental toxicity study of methylsulfonylmethane in rats. Food Chem Toxicol. 2007;45(6):977–984.
- van der Merwe M, Bloomer RJ. The influence of methylsulfonylmethane on inflammation-associated cytokine release before and following strenuous exercise. J Sports Med (Hindawi). 2016;2016:7498359.
Andriy Melnyk
A strength-sports coach and author of programs for beginner and intermediate levels. Writes about training planning.
