Vitamin U

What is Vitamin U?

Vitamin U is not a vitamin. The name belongs to S-methylmethionine, a sulfonium compound with the formula C6H13NO2S and a molecular weight of 163.24, built by plants from methionine and S-adenosylmethionine. It is real, it is genuinely concentrated in cabbage, and it has a defined job inside the plant. What it does not have is a human requirement, a deficiency disease, or an entry in any nutrient table. The letter U was assigned around 1950 by Garnett Cheney at Stanford University School of Medicine, and it stood for ulcer, the condition he was treating. It never stood for a nutrient anyone runs short of.

Capsules sell it as methylmethionine sulfonium chloride, typically at 500 mg. In Japan, Korea, Taiwan and Hong Kong the same molecule is a registered over-the-counter stomach medicine. In the United States and the European Union it has no drug approval at all.

Common Names

• S-methylmethionine, abbreviated SMM, the systematic name

• Methylmethionine sulfonium chloride, or MMSC, the salt in capsules, C6H14ClNO2S, molecular weight 199.70

• Vitamin U, a 1950s coinage no nutrition body recognizes

• Anti-peptic ulcer dietary factor, Cheney's term

Primary Active Compounds

• S-methyl-L-methionine, the naturally occurring enantiomer, and the form specified in most Asian drug registrations

• Dimethyl sulfide, its breakdown product. This is why boiled cabbage smells the way it does, and why brewers boil wort hard to drive the same compound from malt

Key Nutritional Note

Cabbage really is a good source. In a Korean survey of 26 food plants published in Food Science and Technology Research in 2003, the middle leaf of head cabbage measured 46.4 mg per 100 g dry weight, the core 30.6 mg and the outer leaves 26.1 mg. Since raw cabbage is roughly 92 percent water, that is near 2 to 4 mg in 100 g of fresh cabbage. The same survey put spinach at 45.2 mg per 100 g dry weight, worth noting because spinach is not a Brassica.

The chemistry is sound. The problem sits entirely in what the compound is sold to treat.

Primary Functions & Benefits

S-methylmethionine has exactly one fully established function, and it is a plant function.

• In plants, SMM is the main stable form in which sulfur travels through the phloem to developing seeds. Bourgis and colleagues showed this in The Plant Cell in 1999, volume 11, page 1485. A second enzyme converts SMM plus homocysteine back into two methionines at the destination.

• In animals, SMM is absorbed intact and can donate its methyl group, regenerating methionine. Older Soviet radiotracer work confirmed systemic availability and preferential use of the L form.

• The gastric effect studied in rodents is mucus, not acid. SMM increases surface mucin in the stomach lining, an effect blocked by sulfhydryl-group inhibitors.

• Preclinical work also reports antioxidant and anti-inflammatory activity in liver, kidney and lung injury models, via glutathione preservation and Nrf2 signaling.

Everything after the first bullet is animal or cell data. None of it establishes a human benefit.

Who Should Take Vitamin U

The list is short, and it starts with what should happen first.

• Anyone with recurring ulcer or gastritis symptoms should be tested for H. pylori first. That is the intervention with the outcome data.

• People who already eat cabbage, kale, pak choi, broccoli or spinach are getting S-methylmethionine inside a food matrix that also delivers fiber, vitamin C and glucosinolates. No reason to stop.

• People in Japan, Korea or Taiwan using a pharmacist-recommended MMSC product for functional dyspepsia are at least inside a regulatory system that reviewed it. A US capsule has no approved indication.

• Someone already evaluated, H. pylori-negative, with NSAID-related irritation, who wants to try it alongside standard care. Low risk, thin evidence.

Who Should AVOID or Use Caution

Contraindications

• Anyone with untested or untreated H. pylori using this instead of eradication therapy

• Anyone with alarm features: unintentional weight loss, vomiting, difficulty swallowing, anemia, black or bloody stools

Use Caution

• Adults 60 and over with new dyspepsia. The 2017 ACG and CAG dyspepsia guideline, American Journal of Gastroenterology, volume 112, pages 988 to 1013, suggests endoscopy here to exclude upper gastrointestinal cancer.

• Pregnancy and breastfeeding, where there is no human dosing data, only animal screening

• Anyone confusing this with MSM. Methylsulfonylmethane is C2H6O2S, molecular weight 94.14, a sulfone with no amino acid structure and its own separate literature.

Critical Safety Point

The realistic harm here is not toxicity. It is delay. Most peptic ulcer disease is driven by H. pylori, which the International Agency for Research on Cancer classified in 1994, in Monographs volume 61, as carcinogenic to humans, Group 1. A 2025 Nature Medicine analysis estimated 15.6 million lifetime gastric cancers among people born from 2008 to 2017, about 76 percent of them attributable to H. pylori. Managing recurring symptoms with a cabbage derivative can leave a curable, cancer-causing infection in place for years. Get tested.

Recommended Dosages

Supplement capsules (MMSC)

• 500 mg per capsule is the standard US retail unit. That figure traces to a 1990s trial protocol, not to any modern dose-finding study.

Clinical study dosing

• 300 mg per day for six months, in a 2023 Russian study of 37 patients with chronic gastritis.

• 500 mg four times daily, as an add-on in small early-1990s trials by one investigator.

Registered Asian OTC products

• Tablets and granules of L-MMSC, dosed per the national label, usually with antacids and enzymes.

Food

• A 200 g serving of raw cabbage supplies roughly 4 to 8 mg. Cheney's quart of juice delivered maybe 30 to 50 mg a day, well under one modern capsule.

Duration

Human data past six months does not exist. No regulator has set an upper limit.

Timing & Administration

Take it with food. Simulated digestion work found S-methylmethionine stable in stomach acid, with bioaccessibility from a plant source exceeding that of the isolated compound.

Splitting the dose across meals matches how it was studied and how the Asian products are labeled. The compound oxidizes readily and can be heat-sensitive, so store capsules cool, dry and sealed. Cooking degrades it, which is why Cheney insisted on raw juice.

Benefits of Taking Vitamin U

Stated at the honest evidence level.

• Mucosal protection in animals is consistent. SMM raised gastric surface mucin and reduced ethanol- and aspirin-induced lesions in rats. Preclinical.

• A 2025 study in finishing pigs found vitamin U plus antacids in feed reduced gastric ulceration. Preclinical, and a livestock endpoint.

• Hepatoprotective signals in rodents: reduced steatosis in choline-deficient rats, reduced aflatoxin B1 liver injury in mice via Nrf2. Preclinical.

• Lipid effects come from one research group in rats and rabbits around 1979 and 1980, at 1,000 mg per kg per day, roughly a hundred times human dosing. Never replicated.

• In humans, one small 2023 study reported improved dyspepsia scores over six months in chronic gastritis. That is the strongest current human signal, and it is a symptom score.

Potential Negatives & Side Effects

• Sulfurous belching, bad breath and a cabbage-like odor. Dimethyl sulfide release, and the most reliably reported complaint.

• Nausea, loose stools and mild gastrointestinal upset, particularly at four capsules a day.

• The financial negative. A condition with a two-week antibiotic cure does not need a monthly capsule.

• Product identity risk. Because "vitamin U" is not a defined nutrient, no compendial standard governs what goes in the bottle.

Deficiency Symptoms

There is no deficiency state for vitamin U, because it is not an essential nutrient. Humans do not require S-methylmethionine, no intake level has ever been set, no clinical syndrome follows from consuming none of it, and it appears in no dietary reference intake table anywhere. Eat no Brassica vegetables for a lifetime and you will not develop a vitamin U deficiency.

What vitamin U addresses

No nutritional shortfall at all. The letter U was assigned to a disease indication, ulcer, rather than to a deficiency syndrome, which is unusual even among discarded vitamin names. Vitamin P at least described an observed physiological effect. Vitamin U was named after the illness someone hoped it would treat.

Bottom line

The symptoms supplement pages blame on "low vitamin U," meaning heartburn, gastritis and ulcer pain, are symptoms of gastrointestinal disease. They warrant a diagnosis, not a nutrient.

Toxicity Symptoms

At high intake

Gastrointestinal upset and a pronounced sulfur odor on breath and skin. Toxicology screening has not found teratogenicity, and reported acute toxicity is low, consistent with a compound humans eat daily in vegetables.

Signs to reduce or stop

• Persistent nausea, cramping or diarrhea

• Any worsening of the symptoms you started taking it for, which is a reason to see a clinician rather than adjust a dose

General note

No modern Phase I pharmacokinetic study of a standardized S-methylmethionine formulation in humans has ever been published. The safety record is reassuring by inference from food, not by measurement of the supplement.

How Vitamin U Works

• The molecule is a sulfonium: a positively charged sulfur atom carrying three carbon groups, which makes its methyl group easy to hand off. That one property explains the plant biology and everything proposed on the medical side.

• In plants, methionine S-methyltransferase moves a methyl group from S-adenosylmethionine onto methionine. The resulting SMM is stable and mobile, so the plant uses it as the shipping container for sulfur. Homocysteine S-methyltransferase unpacks it at the far end.

• In animal tissue the reaction runs in reverse. SMM plus homocysteine yields two methionines, placing it at the edge of one-carbon metabolism. This is the source of the chicken studies showing a choline-sparing effect.

• The gastric mechanism proposed in rats is sulfhydryl-mediated transport of mucin granules to the apical membrane of gastric mucous cells, thickening the protective mucus layer. Blocking sulfhydryl groups abolishes it.

• Nothing in this mechanism touches Helicobacter pylori. SMM has no meaningful antibacterial activity against it, so even if the mucin effect translates to humans, the infection remains.

Synergistic Supplements

• Standard H. pylori eradication therapy, if you test positive. Nothing here substitutes for it.

• Dexpanthenol, paired with SMM in a 2021 Ukrainian study of 45 patients with chronic pancreatitis and erosive gastritis. Small, and the two agents were never separated.

• Antacids, which is how the Japanese and Korean combination products are built.

• Dietary vitamin C, abundant in the raw cabbage juice Cheney used and never ruled out as the thing that did the work.

Interactions & What NOT to Take

• Do not take it instead of a prescribed antibiotic regimen. The 2024 ACG guideline puts optimized bismuth quadruple therapy for 14 days as first-line treatment for treatment-naive patients.

• Do not use it to mask symptoms while postponing endoscopy if you have alarm features or are 60 or older.

• Do not treat it as interchangeable with MSM, methionine or SAMe. Methionine is C5H11NO2S, molecular weight 149.21, an essential amino acid with a real intake requirement, and loading it raises homocysteine. S-methylmethionine sits elsewhere.

• Caution with methyl-donor stacking. If you already take SAMe, betaine or methylfolate, adding another without a reason is not a plan.

• No documented drug interactions exist, which reflects the absence of interaction studies rather than proven safety.

Special Considerations

The most useful thing to know about this ingredient is what happened to its indication.

Peptic ulcer in 1949 was thought to be a disorder of stress, diet and acid. Cheney's hypothesis fit that world, and his 1952 follow-up in 100 patients called for controlled trials, to his credit. He ran one: a double-blind, placebo-controlled study in inmates at San Quentin Prison, California Medicine, 1956, volume 84, pages 39 to 42, reporting better radiographic healing on cabbage concentrate than on placebo. No independent group has replicated it since, and the concentrate carried ascorbic acid, glutamine, flavonoids and glucosinolates alongside S-methylmethionine, so it cannot tell you which component did anything.

Meanwhile the disease model collapsed. Warren saw the organism in gastric biopsies in 1979, Marshall cultured it in April 1982, and the NIH Consensus Development Panel recommended antibiotics for H. pylori-positive ulcer patients in JAMA in 1994, volume 272, pages 65 to 69.

The practical consequence is worth repeating. Self-treating recurring ulcer or reflux symptoms with a cabbage derivative can leave an H. pylori infection sitting untreated, and untreated H. pylori is a recognized gastric cancer risk factor. Gastric cancer and peptic ulcer produce overlapping symptoms, so persistent upper GI complaints need a workup, not a capsule.

Research Status & Evidence Quality

Strong Evidence For

• Its role as the principal phloem sulfur transport compound in plants

• Its quantification in Brassica vegetables, spinach and asparagus

• Its chemical distinction from MSM, methionine and SAMe

Moderate Evidence For

• Gastric mucin stimulation and reduced experimental lesions in rodents

• Oral absorption and stereoselective metabolism of the L form

Emerging / Preliminary Evidence For

• Symptom improvement in chronic gastritis, from a 37-patient study at 300 mg daily

• Antioxidant and anti-fibrotic protection in rodent liver, kidney, lung and lens injury models

• Lipid lowering, from rat work at 1,000 mg per kg per day by one group in 1979 and 1980

Research Limitations

The human evidence has three problems at once. It is old, it is geographically isolated in Soviet, Russian and East Asian literature, and it comes from single investigators no independent group has reproduced. A 2026 critical review in Pharmaceuticals, volume 19, article 743, worked through the literature and concluded that no contemporary human pharmacokinetic study of a standardized formulation exists, and that Phase II trials in one defined indication are still needed. Seventy-seven years after the first paper, that is the state of play.

Summary & Key Takeaways

S-methylmethionine is a real plant compound with a real biological job, sold under a name invented for a disease that medicine now cures with antibiotics. Cabbage juice may well have helped Cheney's patients. What his trials could not do, and what nothing since has done, is show that S-methylmethionine specifically heals ulcers in humans, or that it matters once you can eradicate the organism causing them.

Bottom Line

The plant biology is solid, the rodent gastroprotection is consistent, and the human evidence is a handful of small unreplicated studies. Eating cabbage is a fine idea. Buying a 500 mg capsule to treat an ulcer is buying a 1949 answer to a question settled in 1994.

Key Safety Points

• Recurring ulcer, gastritis or reflux symptoms need an H. pylori test, not a supplement. Untreated infection is a Group 1 carcinogen sitting in your stomach.

• Gastric cancer and peptic ulcer can present identically. Weight loss, vomiting, swallowing difficulty, anemia or black stools require evaluation now.

• New dyspepsia at 60 or older warrants endoscopy under current guidelines.

• Do not confuse it with MSM or methionine. Different molecules, different literatures.

Special Note

This one leaves a rule behind. When a supplement's name encodes a disease rather than a nutrient, go find out when that disease was last redefined. Vitamin U was named for the ulcer, and then the ulcer got a cure. The name outlived the medicine that inspired it, which is exactly why it still sells.