Winnie Zhao, National Center for Health Research
Fish is a healthy source of nutrition, and that is why fish oil supplements are popular. They contain omega-3 fatty acids, a type of fat that the body needs but cannot make on its own. These supplements typically contain two main types of omega-3s, EPA and DHA, that are found naturally in oily fish such as salmon and sardines. It makes sense that fish oil supplements would improve our health, but numerous large, carefully run studies show that the people who take these supplements are not less likely to have heart attacks, strokes or early death compared to people who do not take them. There may be one exception, so here is what you need to know.
What Research Shows
A clinical trial called the STRENGTH trial studied more than 13,000 adults who were already at high risk for heart disease [1]. Researchers gave half of them 4 grams of omega-3s (EPA and DHA) daily and gave the other half a placebo pill. The fish oil dose was much higher than typical over-the-counter supplements. After 3.5 years, major heart problems such as heart attacks and strokes happened at almost the same rate in both groups. Even these extra-high doses of EPA and DHA did not seem to provide protection.
But the results were worse in the real world. Researchers started a study with more than 415,000 healthy British adults from a British database called the UK Biobank, tracking them for 12 years to see who used fish oil supplements and who developed heart problems. The people taking fish oil supplements were less likely to have heart attacks than those who did not take them. What was surprising and worrisome was that the people who took fish oil supplements were slightly more likely to develop atrial fibrillation (also called A-fib), which is a dangerous irregular heartbeat, and they also had more strokes. Other studies have had similar results: people taking more than about 1 gram of marine omega-3s daily were 13% more likely to develop A-fib. [1]
In contrast, a prescription-only fish oil product containing purified EPA was beneficial to people who already had very high levels of triglycerides (a type of blood fat) in their blood and were already taking cholesterol-lowering statin medications. When researchers gave these patients 4 grams of this specialized EPA daily, they were 25% less likely to have heart attacks, strokes, or urgent heart procedures during the next five years.[2]
This success story is interesting, but it doesn’t mean the fish oil supplements in most stores are likely to help you. This study did not use the typical fish oil supplement you can buy at the pharmacy. It was a purified, prescription-strength product used to treat a specific medical condition in people who were already receiving other heart medications.
What this Means for You
Given all this evidence, what do the experts recommend? The American Heart Association suggests that people who have already suffered a heart attack or have congestive heart failure might consider taking about 1 gram per day of combined EPA and DHA fish oil supplements, but only if their doctor agrees. Even for these patients, the potential benefit appears to be very small. [3]
For healthy people hoping to prevent heart disease, the evidence does not support taking fish oil supplements. Instead, health organizations consistently recommend getting omega-3s by eating fish. The American Heart Association advises eating two servings of oily fish each week, such as salmon, sardines, mackerel, or trout [3]. When you eat fish, you get omega-3s along with high-quality protein, vitamin D, selenium, and other nutrients [4]. Plus, fish can replace less healthy foods in your diet.
The Bottom Line: For most people, fish oil supplements cost money but do not provide any health benefits and may instead increase the chances of developing an irregular heartbeat. Your money and effort are better spent on strategies that actually work. Eat fish regularly, stay physically active, keep your blood pressure and cholesterol in healthy ranges, and do not smoke. However, if you have very high triglycerides that do not improve with these lifestyle changes, and you are taking statins, then you may want to ask your doctor whether prescription-strength EPA might be appropriate for you.
References
[1] Nicholls SJ, Lincoff AM, Garcia M, et al. Effect of high-dose omega-3 fatty acids vs corn oil on major adverse cardiovascular events in patients at high cardiovascular risk: the STRENGTH randomized clinical trial. JAMA. 2020;324(22):2268–2280. doi:10.1001/jama.2020.22258
[2] Chen G, Qian ZM, Zhang J, et al. Regular use of fish oil supplements and course of cardiovascular diseases: prospective cohort study. BMJ Med. 2024;3(1):e000451. doi:10.1136/bmjmed-2022-000451.
[3] Bhatt DL, Steg PG, Miller M, et al. Cardiovascular risk reduction with icosapent ethyl for hypertriglyceridemia. N Engl J Med. 2019;380(1):11–22. doi:10.1056/NEJMoa1812792
[4] American Heart Association. Fish and Omega 3 Fatty Acids. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/fish-and-omega-3-fatty-acids. Updated August 23 2024. Accessed July 16 2025.