Does Fish Oil Help AFib?

Medically Reviewed by James Beckerman, MD, FACC on June 30, 2022
3 min read

You may be thinking about taking fish oil to improve your health. But when it comes to atrial fibrillation (AFib), should you reel it in or cut it loose?

Fish oil is a source of omega-3 fatty acids. You can get it from eating fish and seafood, including salmon, trout, oysters, and crabs. Non-fish sources include nuts and seeds.

You can take fish oil omega-3 fatty acid supplements for a variety of health reasons. There’s strong evidence that taking omega-3s can lower triglycerides, a kind of fat that builds in your blood.

You can buy supplements over-the-counter, or your doctor may suggest prescription-strength fish oil, especially if your triglycerides are very high.

You may think you’re doing your heart a favor if you add fish oil to your routine if you are at risk of developing AFib or already have it.

But that’s not always the case.

Over time, many people have thought that fish oil could be helpful for irregular heartbeats (arrhythmias) and specifically AFib, says Christine Albert, MD, MPH, chair of the Department of Cardiology at Cedars Sinai Hospital in Los Angeles.

Some research actually found a greater risk of AFib associated with fish oil but others haven’t, she says. So whether it helps or not has remained an open question.

To try to get to the bottom of it, Albert and her team analyzed seven research studies that included more than 80,000 people. Seventy-two percent took part in trials where people took a gram or less of omega-3 fatty acids a day. The rest of the people were in trials that took more than a gram a day.

Here’s what they found:

At lower doses, the risk of developing AFib was slight, but the risk was greater in the higher dose groups, Albert says. People who took more than a gram per day had a 49% greater risk of developing AFib. That’s compared to only 12% of patients who took one gram or less of the supplement each day.

She adds that more research is needed to know for sure what other factors might affect who is more prone to develop the heart rhythm problem while taking fish oil supplements.

It also isn’t known if AFib goes away when fish oil is stopped. That’s something Albert’s team is studying.

There have been smaller trials of people with AFib that were given fish oil as an antiarrhythmic – to make it go away -- and it wasn’t effective. Albert says. On the other hand, it didn’t make it worse, either.

“We know what lifestyle factors might worsen atrial fibrillation, like gaining weight and drinking too much alcohol. I would put fish oil in that group. Then, I would say if you’re on fish oil and your atrial fibrillation gets worse, maybe you should stop the fish oil,” she advises.

“It’s a very commonsense approach when you don’t have clear randomized, controlled data to tell you what to do.”

Could fish oil help put your heart back in rhythm if you have persistent or permanent AFib?

There have been older, small trials showing mixed results. “When you put them all together, they didn’t show a big difference, '' Albert says.

“The main end point in these trials has been recurrence of atrial fibrillation, which really doesn’t measure what a patient perceives. Maybe one recurrence in 10 years is OK, but 10 is different."

A lot of these trials were not set up to answer these questions, Albert adds.

So what should you do concerning AFib and fish oil? Talk to your doctor, Albert says. Ask, “Is taking low-dose fish oil helpful to me?”

It’s important to know that fish oil supplements can interfere with drugs you may take to prevent a stroke. Anticoagulants help lessen clotting and “thin” your blood. If you take fish oil with them, you could bleed.

When you decide to take a supplement or stop one, you need to ask your doctor to weigh in, stresses Albert. “Doctors often learn things about supplements from these trials that patients don’t know or from just reading the literature. So it’s really important to ask your doctor whether it’s the right thing for you.”