The side effects and health benefits of omega-3s, found in fish oil, are still being explored. The latest: A recent study found that daily purified omega-3 oil lowered the risk of a cardiac event, but raised the risk of hospitalization for atrial fibrillation, which can include heart palpitations.
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You might have experienced heart palpitations if you have felt that your heart is suddenly skipping around, fluttering, beating fast or pounding, Mayo Clinic says. And here's what we know about the possible impact of omega-3s.
Read more: 5 Pros of Fish Oil Supplements — and 4 Cons to Know
The Many Faces of Omega-3s
Omega-3s are a group of fatty acids naturally found in foods, such as seafood, soybeans and flaxseed, and in dietary supplements like fish oil. According to the Office of Dietary Supplements (ODS), the three main fatty acids in this group are:
- Alpha-linolenic acid (ALA).
- Docosahexaenoic acid (DHA).
- Eicosapentaenoic acid (EPA).
Fish oil supplements contain both DHA and EPA fatty acids, according to the Mayo Clinic. Omega-3 supplements, which also include flaxseed oil, krill oil and others, are the most common non-vitamin, non-mineral supplements consumed by adults and children alike, according to the National Center for Complementary and Integrative Health (NCCIH).
But as with many supplements, it may be hard to know exactly what you're getting, says Seth Shay Martin, MD, MHS, director of the Advanced Lipid Disorders Program and associate professor of medicine at Johns Hopkins University in Baltimore.
"Whenever we talk about omega-3s and fish oil, it's very important to be specific about the source of the oil. Is it a purified, regulated product that's been studied in clinical trials? Or are we talking about something less pure and reliable and lacking evidence? We can't just lump them all together," Dr. Martin says.
Omega-3s for Cardiac Health
The dish on fish? The jury is still out on whether the fish oil you are taking could lead to heart palpitations, but there is some evidence that it may be a factor.
A large trial of over 8,000 patients published January 2019 in the New England Journal of Medicine found that for patients with heart disease, diabetes or other risk factors, the risk of an adverse cardiovascular event, like heart attack, unstable angina or death was significantly lower in the group taking 4 grams of icosapent ethyl daily, a highly purified form of EPA, one of the omega-3 fatty acids found in fish oil, than in the placebo group.
However, the study also found that more patients in the icosapent ethyl group were hospitalized for atrial fibrillation (AFib) as compared to the placebo group. AFib is an irregular heartbeat, and though many people with AFib don't recognize it as a serious condition, untreated AFib can lead to blood clots, stroke and heart failure, according to the American Heart Association. One of the main symptoms of AFib is heart palpitations, according to the Mayo Clinic.
The study authors report that overall the rate of AFib was low however, at 3.1 percent (versus 2.1 percent in the placebo group).
"We have to keep in mind that [this study] tested a very specific formulation," Dr. Martin says. "That specific medicine is not the same thing you would find in over-the-counter fish oils, which can be much less pure and don't necessarily have the same amount of the active ingredient, EPA, that was used in that trial," Dr. Martin says.
While the effects of fish oil are still being explored, both the NCCIH and ODS do not list palpitations as a possible side effect just yet. Instead, fish oil is commonly linked to:
- Bad taste in mouth.
- Bad breath.
- Stomach upset.
- Smelly sweat.
Omega-3s From Food
Though fish oil and omega-3 supplementation may be controversial, that doesn't mean there is no role for these essential fatty acids, Dr. Martin says. "People can get omega-3s as part of a balanced, heart-healthy diet."
Eating your omega-3s rather than taking them in supplement form may yield higher quality and other key nutrients, and may have greater health benefits, NCCIH points out.
So think about getting omega-3s from food sources. The U.S. Department of Agriculture and U.S. Department of Health and Human Services recommend at least 8 ounces of seafood per week for adults. Aim for those high in EHA and DHA omega-3s and low in methyl mercury, such as:
Read more: 18 Foods High in Omega-3s for Better Brain Health
- Mayo Clinic: “Heart Palpitations”
- National Institutes of Health: Office of Dietary Supplements: “Omega-3 Fatty Acids”
- Mayo Clinic: “Fish Oil”
- National Center for Complementary and Integrative Health: “Omega Supplementation in Depth”
- Seth Shay Martin, MD, MHS, director, Advanced Lipid Disorders Program, Ciccarone Center, and associate professor of medicine, Johns Hopkins University, Baltimore
- New England Journal of Medicine: “Cardiovascular Risk Reduction With Icosapent Ethyl for Hypertriglyceridemia”
- American Heart Association: “What Is Atrial Fibrillation (AFib or AF)?”
- Mayo Clinic: “Atrial Fibrillation”
- U.S. Department of Agriculture and U.S. Department of Health and Human Services: “2015-2020 Dietary Guidelines for Americans”