Study: High Doses of Omega-3 Supplements May Not Be Heart-Healthy

A group of transparent yellow capsules, meant to be omega-3 supplements, on a light blue backgroud.

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Key Takeaways

  • A new meta-analysis found that people who took more than one gram of omega-3 fatty acid supplements per day had an increased risk of developing a heart rhythm problem called atrial fibrillation (AFib).
  • AFib is not a life-threatening condition, but it can lead to heart failure or stroke.
  • While they can be part of a heart-healthy lifestyle, most experts recommend getting omega-3 fatty acids from food instead of supplements.

New research has shown that taking high doses of omega-3 supplements may increase a person's risk of developing a type of irregular heart rhythm called atrial fibrillation (also called AFib).

While atrial fibrillation is not life-threatening, it can lead to serious cardiovascular conditions, like stroke or heart failure.

Certain dietary patterns, including those that emphasize omega-3 fatty acids, are often linked to better cardiovascular health and are even recommended for patients to reduce their risk of heart disease—guidance that the new research brings into question.

What the Study Found

A new meta-analysis published in the journal Circulation found that omega-3 supplements were slightly associated with a higher risk of AFib. The risk was related to how much of an omega-3 supplement a person took—in other words, the higher a person's omega-3 intake, the higher their risk of AFib was.

According to a press release discussing the study, the researchers said that "patients who took more than one gram per day of omega-3 fatty acids had a 49% increased risk of developing atrial fibrillation."

A person's risk of developing AFib is increased by stress, high blood pressure, diabetes, obesity, alcohol consumption, and heart disease.


Christine M. Albert, MD, MPH, professor of cardiology, chair of the department of cardiology in the Smidt Heart Institute, and senior author of the study, tells Verywell that "atrial fibrillation is the most common heart rhythm disturbance" and that by age 80-85," about 15% of the population has atrial fibrillation."

Earlier this year, Albert published research that showed omega-3s did not increase or decrease atrial fibrillation risk. However, some studies show that omega-3s did increase the risk of AFib.

The mixed results prompted Albert to conduct the new meta-analysis to figure out why the research findings varied so much.

The researchers compared the results from seven randomized controlled trials that focused on omega-3s and AFib risk. "The studies are very different," says Albert. "They use different dosages of omega-3s."

Albert's study, as well as others that used 1 gram or less of omega-3s, did not lead to an increased risk of AFib. However, the studies that used more than 1 gram of omega-3s did show a higher AFib risk.

A meta-analysis cannot be used to prove a connection between omega-3 and AFib risk—Albert says that a randomized control trial would be needed to make that claim.

Should Doctors Prescribe Omega-3s?

While they might not be enough to prove a definitive link, Albert says that the findings of the new meta-analysis do give healthcare providers something to think about when they are considering prescribing high doses of omega-3 supplements to their patients.

It's known that patients with AFib often have more cardiovascular disease and do not live as long as patients without the condition. Therefore, finding ways to help them lower their risk is a priority.


"The hope was that the omega-3s would actually prevent [heart disease], but it did not work that way," says Albert. "And in fact, it might be slightly increasing the risk in the population."

However, it's important to note that the high doses of omega-3 supplements that are associated with a higher risk of AFib are not available over the counter (OTC); they would only be available by prescription.

Judith M. Hinderliter, MPH, RDN, LDN, a clinical dietitian for the UNC Wellness Centers at Meadowmont Cardiac Rehabilitation Program, tells Verwell that the studies associating omega-3 intake and AFib risk were using prescription-strength supplements, which "are often prescribed to people with very high triglycerides, a type of blood fat linked to an increased risk of heart attack and stroke."

While there is evidence that prescription-strength omega-3s can lower triglycerides, Hinderliter says that they are somewhat controversial. "Their ultimate benefit to the heart is not clear. This recent study suggests caution is in order," she adds.

Why You Need Omega-3s

Omega-3s support heart, brain, and eye health. Studies have shown that omega-3s may protect people from disease and help people live longer.

"Human beings do not make omega-3 fatty acids in our body," Grace Derocha, MBA, RD, CDCES, a spokesperson for the Academy of Nutrition and Dietetics, senior health care analyst, and expert in cardiovascular nutrition, tells Verywell. "We have to consume omega-3s in some way."

The three main types of omega-3s include:

  • Eicosapentaenoic Acid (EPA)
  • Docosahexaenoic Acid (DHA)
  • Alpha-linolenic Acid (ALA)

EPA and DHA are mainly found in fish while ALAs are found in plant sources, especially flaxseeds and walnuts. The American Heart Association (AHA) recommends consuming two servings of fish, particularly fatty fish, per week, which could include salmon, sardines, and albacore tuna.

Other Aspects of a Heart-Healthy Lifestyle

Omega-3s are generally considered part of a heart-healthy lifestyle, but most experts recommend getting them from food sources rather than from supplements.

Derocha says that it's also important to stay hydrated and eat a variety of fruits, vegetables, legumes, and whole grains. "I like to talk about the things that people should add to nourish," says Derocha. "But limiting sodium and excess fat and excess added sugars are also important when we try to balance everything."

Exercise is another crucial contributor to heart health. Derocha says that people should try to follow the AHA's recommendations of getting 150 minutes of cardiovascular exercise and two resistance training workouts per week. It's also helpful to try to find ways to stand or walk more during the day.

Talk to Your Doctor About Supplements

It's important to discuss any supplements, including fish oil or omega-3 supplements, with your doctor before you try them.

The Food and Drug Administration (FDA) does not review dietary supplements for safety or effectiveness. That's why Derocha says that it's important to be clear about where a supplement that you're interested in taking is coming from.

"As a dietitian, I recommend trying to get things through food as much as possible," says Derocha. "But also listen to your doctor and be very aware of what a supplement is, what it means, and what is in the one that you are taking. I've seen supplements that say omega-3s or fish oil but the DHA and EPA are barely there, so what are you taking it for?"

Ask your doctor and pharmacist for recommendations, then check for third-party verification on a supplement that you are considering.

You can look for the USP Verification Mark on a particular supplement to confirm that it contains the ingredients that are listed on the label and does not have unsafe levels of contaminants.

On the other hand, Derocha says that in light of the recent study, it's also important to make sure that you're not overdoing it with supplementation.

Albert says that the bottom line of their study's findings is that "every supplement potentially has consequences." That's why you should talk to your doctor about whether a supplement is right for you, and if so, how much of it you need to take.

What This Means For You

Taking high doses of omega-3 supplements might increase your risk for an irregular heart rhythm called AFib. Most experts agree that it's better to get omega-3s through food (such as fatty fish) than through supplementation (like fish oil pills).

You should talk to your doctor about the type and dose of omega-3s that's right for you. In some cases, an OTC supplement might be helpful. If you do need a higher dose, your doctor can prescribe it for you after discussing its risks and benefits.

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5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Gencer B, Djousse L, Al-Ramady O, et al. Effect of long-term marine omega-3 fatty acids supplementation on the risk of atrial fibrillation in randomized controlled trials of cardiovascular outcomes: a systematic review and meta-analysisCirculation. 2021. doi:10.1161/circulationaha.121.055654

  2. American College of Cardiology. Alcohol Abuse Increases Risk of Heart Conditions as Much as Other Factors. Published January, 2017.

  3. Albert C, Cook N, Pester J et al. Effect of marine omega-3 fatty acid and vitamin d supplementation on incident atrial fibrillationJAMA. 2021;325(11):1061. doi:10.1001/jama.2021.1489

  4. Bhatt D, Steg P, Miller M et al. Cardiovascular risk reduction with icosapent ethyl for hypertriglyceridemiaNew England Journal of Medicine. 2019;380(1):11-22. doi:10.1056/nejmoa1812792

  5. Harris W, Tintle N, Imamura F et al. Blood n-3 fatty acid levels and total and cause-specific mortality from 17 prospective studiesNat Commun. 2021;12(1). doi:10.1038/s41467-021-22370-2