Research review
Does fish oil help with ulcers? What the research does and doesn't show
The human evidence on fish oil and peptic ulcers is thin and contradictory: a large 2017 observational study found higher dietary omega-3 intake associated with lower H. pylori eradication success, while a small, dated study and an animal study point toward faster ulcer healing.
The evidence doesn't support fish oil as a treatment for peptic ulcers, and one large observational study found the opposite of a benefit: people with higher dietary omega-3 intake had a lower success rate when treated for H. pylori, the bacterium behind most peptic ulcers. A small, old, methodologically limited human study and an animal study point the other way, toward faster ulcer healing — which leaves the human evidence thin and contradictory rather than supportive.
What the evidence doesn't support
It doesn't support fish oil as a treatment for an existing peptic, gastric or duodenal ulcer, and it doesn't support fish oil as protective against H. pylori infection or its treatment — the largest, most rigorous study on that specific question found the opposite association. It doesn't support using fish oil in place of standard ulcer treatment (acid-suppressing medication, and antibiotics where H. pylori is involved), and none of the research below tested fish oil against those treatments.
What the trials found
A 2017 observational study of 4,014 people in Japan measured H. pylori infection status and dietary intake by questionnaire. Among 389 H. pylori-positive people with gastritis or duodenal ulcers who received standard eradication therapy (a course of two antibiotics plus a proton pump inhibitor), higher dietary omega-3 fatty acid intake — along with higher dietary cholesterol and egg intake — was associated with a lower success rate of eradication therapy. This is dietary intake data, not a fish oil supplement trial, and it's an association, not a controlled test of cause and effect, but it's the largest and most rigorous study specifically on omega-3 and ulcer-related treatment outcomes.
Running the other direction, a small 1996 human study gave a fish oil preparation to 21 patients with stomach or duodenal ulcers; 85% showed ulcer healing on endoscopy, compared with 60% in patients who didn't take it. The study is old, small, and its abstract doesn't describe randomization or blinding, so it carries much less weight than the 2017 study above. A 1995 animal study found fish oil reduced the size of drug-induced stomach lesions in rats compared with olive oil or a normal diet — a laboratory finding in animals, not evidence about people.
Taken together, this is a small and contradictory literature: one larger, better-designed human study points against a benefit for treatment success, while a small, dated, poorly described human study and an animal study point toward faster healing. Neither direction is strong enough to draw a conclusion from.
Questions people ask
Does fish oil help ulcers?
The human evidence is thin and contradictory. A larger, more rigorous 2017 study found higher dietary omega-3 intake associated with a lower success rate of H. pylori ulcer treatment; a small, older, poorly described study found the opposite. Neither is strong enough to support a recommendation either way.
Can fish oil cause stomach ulcers?
No study reviewed here found that fish oil causes ulcers. The 2017 study found an association between higher omega-3 intake and lower treatment success in people who already had an H. pylori-related ulcer, which is a different question from whether fish oil causes ulcers to form.
Should I take fish oil with ulcer medication?
None of the research above tested fish oil alongside acid-suppressing medication or antibiotics prescribed for H. pylori, for an interaction. If you have a diagnosed ulcer or H. pylori infection, ask your doctor before adding any supplement.
When to talk to a doctor
Ulcer symptoms — burning stomach pain, especially between meals or at night — and a diagnosed H. pylori infection both need a doctor's evaluation and standard treatment. Fish oil is not a treatment for peptic ulcers or H. pylori infection, and nothing in the evidence above supports using it as a substitute for prescribed treatment.
Related reading: fish oil benefits: what's established and what isn't and fish oil and liver health: what the research does and doesn't show.
Sources
- Higher dietary cholesterol and ω-3 fatty acid intakes are associated with a lower success rate of Helicobacter pylori eradication therapy in Japan In a study of 4,014 people, higher dietary intake of omega-3 fatty acids and fish was associated with a lower success rate of standard antibiotic treatment for H. pylori infection in people with gastritis or duodenal ulcers.
- [Optimization of dietary fat composition in erosive and ulcerative diseases of the gastroduodenal area] A small, methodologically unclear 1996 study found 85% of ulcer patients given a fish oil preparation showed healing, versus 60% of those who did not take it.
- Effect of fish oil on indometacin-induced gastric lesions in rats In rats, fish oil reduced the size of drug-induced stomach lesions compared with olive oil or a normal diet — an animal finding, not evidence in people.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.