Is Fish Oil Worth Taking? What the Research Actually Shows

For most healthy adults, fish oil pills probably aren't worth it: the biggest trials found everyday doses didn't significantly cut major heart problems, a 2026 trial found no memory benefit, and fish oil is linked to a higher risk of an irregular heartbeat. Eating fish has better support. A few groups of patients may benefit from prescription omega-3s, but that's a decision for your doctor.

Fish oil supplies two omega-3 fats, EPA and DHA. You also get them by eating fish, which the FDA notes provides omega-3s along with nutrients like iron and choline.

Drugstore fish oil is a dietary supplement. By law, the FDA does not approve supplements before they're sold. The companies that make them are responsible for safety and accurate labels.

Prescription omega-3s are a different product. Drugs like Vascepa (icosapent ethyl) are high-dose omega-3s that were tested in large trials of specific patients. A capsule from the vitamin aisle shouldn't be assumed to do the same thing.

The evidence is mixed at best. In the VITAL trial, 25,871 adults took 1 gram of fish oil a day or a placebo for about five years. Fish oil did not significantly reduce major cardiovascular events overall. Heart attacks were 28 percent lower, but that was a secondary finding. In the ASCEND trial, 15,480 adults with diabetes took the same dose for about seven years. There was no significant effect on serious vascular events, though cardiovascular deaths were 19 percent lower.

High-dose trials split. REDUCE-IT gave 8,179 people 4 grams a day of icosapent ethyl and reported a 25 percent drop in cardiovascular events. But STRENGTH, which gave 13,078 high-risk patients 4 grams a day of a different omega-3 drug, found no benefit: 12.0 percent had a major event, versus 12.2 percent on a corn oil placebo. It was stopped early.

Some experts point to the placebo. REDUCE-IT compared its drug with mineral oil, and a 2022 analysis of the trial's blood samples found several inflammation markers rose in the mineral oil group while barely changing in the drug group. Critics say that may have made the drug look better than it is. REDUCE-IT's lead investigator says the benefit holds up. STRENGTH used corn oil.

The American Heart Association recommends one to two servings of seafood a week. It does not recommend omega-3 supplements for people who aren't at high risk of heart disease.

This is the risk most people haven't heard about. A 2021 analysis of seven randomized trials with 81,210 people found omega-3 supplements were tied to a 25 percent higher risk of atrial fibrillation, or AFib, a type of irregular heartbeat. The risk was 49 percent higher in trials using more than 1 gram a day, and 12 percent higher at 1 gram or less. Because the data came from randomized trials, this is stronger evidence than most supplement warnings.

In STRENGTH, 2.2 percent of people on the omega-3 drug developed AFib, compared with 1.3 percent on corn oil.

Real-world data point the same way for healthy people. A 2024 UK Biobank study followed 415,737 adults without heart disease for a median of about 12 years. Regular fish oil users were 13 percent more likely to develop AFib and 5 percent more likely to have a stroke. But among people who developed AFib or heart failure, fish oil use was linked to a lower risk of their condition getting worse. This was an observational study, so it shows a link, not proof.

A new trial says no. Researchers at the University of Southern California gave 365 adults ages 55 to 80 either 2,000 mg of DHA a day or a placebo for two years. All of them rarely ate fish and had a higher risk of Alzheimer's. Nearly half carried APOE4, the strongest known genetic risk factor for late-onset Alzheimer's.

The supplement did reach the brain. DHA in the fluid around the brain rose an average of 17 percent after six months. But memory and thinking scores were no better than placebo, and the supplement didn't prevent shrinkage of the hippocampus, a key memory region. "Our results do not support fish oil supplements as a preventive measure against Alzheimer's," said lead investigator Dr. Hussein Yassine.

That fits the bigger picture. The NIH's Office of Dietary Supplements says trials generally find omega-3 supplements don't affect thinking in healthy older adults or in people with Alzheimer's.

For most families, food is the better bet. The FDA says strong evidence shows that eating fish, as part of a healthy eating pattern, may have heart health benefits. The USC researchers also suspect omega-3s from a balanced diet may work differently than isolated, high-dose supplements.

The FDA and EPA advise:

Some people have a real reason to talk with a doctor about omega-3s:

Side effects are usually mild: a fishy taste, bad breath, heartburn, nausea or diarrhea. High doses may increase bleeding time, so if you take a blood thinner such as warfarin, check with your doctor or pharmacist first.

Healthy, Again. is health news, not medical advice. Talk to your doctor before changing any medicine or supplement.