Evidence-based·Last reviewed May 30, 2026·How we grade evidence

Methylmethionine sulfonium

Amino-acidMethionine derivative

Useful mainly for no well-established clinical use; historical interest in gastric mucosal protection.

Quick decision guide

May help most

no well-established clinical use; historical interest in gastric mucosal protection

Common dosing range

No established dose; older products used roughly tens of milligrams to a few hundred mg/day

When to expect effects

Unclear

Watch out for

Human evidence is old and very limited; not a substitute for treatment of ulcers or reflux

What is it

Methylmethionine sulfonium (S-methylmethionine), historically nicknamed 'vitamin U,' is a methylated amino-acid derivative found in cabbage and other vegetables. It was studied decades ago for protecting the stomach lining and is sometimes marketed for digestive complaints.

Is it worth it for you?

Use this as a quick fit check, not a diagnosis.

Worth considering if…

You are simply curious about the 'vitamin U' history

Probably skip if…

You have an ulcer, gastritis, or reflux that needs evaluation
You want evidence from modern controlled trials
You expect a reliable digestive benefit

Evidence at a glance

gastric mucosal protection

Mixed Evidence
Effect
Unclear
Best fit
not established
Time
Unclear

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

gastric mucosal protection

Mechanism only
Mixed Evidence

Early and largely preclinical work suggested S-methylmethionine may support the gastric mucosa, the basis for its old 'vitamin U' anti-ulcer reputation. There are no robust modern randomized trials demonstrating clinical benefit in humans.

Effect size
Unclear
Time to effect
Unclear
Best fit
not established

Bottom line: Any gastric-protective effect is supported only by old and mechanistic data, not by modern clinical evidence.

SourceMaxis et al., 1965 — PubMed

How to take it

1. Typical dose
No standardized dose established
2. Timing
Historically taken with meals
3. With food
With food
4. How long to try
Not established

What to track

Upper-abdominal symptoms
Heartburn frequency

Safety

Know the common side effects, key cautions, and who should avoid it.

Common side effects

Not well characterized; generally regarded as low-risk at dietary amounts

Who should avoid it

  • People using it in place of evaluated treatment for ulcers or reflux

Pregnancy & breastfeeding

No adequate safety data; avoid supplemental use in pregnancy and breastfeeding.

Choosing a product

What to look for on the label — and what to be skeptical of.

Look for…

Clear identification as S-methylmethionine
Stated amount per serving

Be skeptical of…

'Vitamin U cures ulcers'
'Heals the gut lining'

References by claim

gastric mucosal protection

Maxis et al., 1965 — PubMed (1965) link

Track Methylmethionine sulfonium with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

Coming to App Store
Evidence-based·Last reviewed May 30, 2026·Evidence current as of May 30, 2026·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.