Should You Take a Fish Oil Supplement?

Do fish oil supplements boost heart health?

Diet-based studies in the 1970s linked higher omega-3 levels to a significant reduction in cardiovascular risk, especially stroke risk. Based on that, Natarajan says, there was a flurry of interest in “capturing that macronutrient in a pill to see if that similar efficacy could be achieved outside of food.”

But efforts to bottle the benefits haven’t panned out. While some studies show possible advantages, many large randomized controlled trials failed to show clear cardiovascular benefits from fish oil supplements, Natarajan says.

At the same time, concerns emerged as studies linked high doses of fish oil to an increased risk of irregular heart rhythm. A 2021 meta-analysis published in Circulation found that people taking fish oil supplements had a 25 percent higher risk of atrial fibrillation compared to those who didn’t take them.

“Back in the day, I used to take over-the-counter fish oil,” says Andrew Freeman, M.D., director of cardiovascular prevention and wellness at National Jewish Health in Denver. “As time has gone on, the evidence now points away from it. … None of the professional society guidelines for cardiology recommend over-the-counter fish oil at this time.”

The only exception, Freeman says, is for patients with very high triglyceride levels, who may be prescribed a type of highly purified, prescription-grade fish oil.

Do fish oil supplements support brain health?

Plenty of research shows that eating fish can protect memory, improve thinking skills and slow cognitive decline. But when it comes to fish oil supplements, the evidence is less clear, says Lynne Shinto, M.D., professor of neurology at Oregon Health & Science University. 

So far, most randomized controlled trials have found no brain benefits among people who take fish oil capsules, she says, but more research is needed.

Still, some recent findings are promising. A 2022 systematic review that included nine randomized clinical trials found that taking fish oil may improve memory, learning, mental sharpness and blood flow in the brain.

And a 2023 analysis that followed 1,000 older adults for six years found that those who regularly took omega-3 supplements had a 27 percent lower risk of developing Alzheimer’s disease. However, the fish oil supplementation in that study was based on patient reporting, which limits the study’s reliability compared to randomized controlled trials, Shinto says.

Shinto’s own research offers new insight into who might benefit most from supplements. In a 2024 randomized clinical trial published in JAMA Network Open, she followed about 100 older adults over age 74 with no signs of dementia for three years. The study found that for most people, there wasn’t a significant benefit from taking over-the-counter fish oil supplements.

But for those carrying the APOE4 gene, a genetic marker linked to higher Alzheimer’s risk, the supplements appeared to slow brain cell degeneration.

“The APOE4 people who got the fish oil had better brain connectivity over three years compared to those who were on placebo,” Shinto explains. “It was a significant finding.”

While Shinto is planning a larger clinical trial to confirm the results, she emphasizes that her research also showed that over-the-counter dosages of fish oil are safe and have few side effects.

“The takeaway is, we can’t say for sure that it’s going to help … but it certainly seems safe enough that you could take it,” she says.

Can fish oil help with joint pain and muscle strength?

Fish oil’s anti-inflammatory properties have made it a popular supplement among people hoping to ease joint pain or preserve muscle, and some research indicates it might be helpful.

For example, a 2023 meta-analysis of nine trials involving more than 2,000 people with osteoarthritis found that those who took omega-3 supplements reported less pain and better movement compared to those who took a placebo. Osteoarthritis is a common condition that occurs when the cartilage between bones breaks down, causing joint pain.

Fish oil supplements have shown “a lot of promise in terms of reducing cartilage degradation, reducing inflammation and probably improving outcomes,” says Stephen Cornish, a kinesiologist at the University of Manitoba in Canada who has studied fish oil’s effect on muscles, bones and joints.

However, results across human studies have been mixed, Cornish says, and more randomized controlled trials are needed.  

As for muscle strength, some small studies indicate that fish oil may help preserve muscle mass or improve muscle function, particularly in older adults. A meta-analysis led by Cornish in 2022 found that omega-3 supplements did not boost muscle mass but did improve lower-body strength and mobility in older adults, especially when combined with resistance training.

“One thing we are theorizing, and that other researchers have looked at as well, is that it may actually enhance neuromuscular communication … in terms of firing the muscle appropriately and firing it more forcefully,” Cornish says.

What to know if you want to try fish oil

If you’re interested in trying a fish oil supplement, here are a few things to keep in mind:

• Stick to safe doses. Health officials recommend consuming no more than 5 grams per day, or 5,000 milligrams (mg) of EPA and DHA combined from dietary supplements. A typical fish oil supplement provides about 1,000 mg of fish oil, containing 180 mg of EPA and 120 mg of DHA, but doses vary widely.
• Look for third-party certification. What’s on the label isn’t always what’s in the bottle, so look for third-party seals (like NSF International, USP, or ConsumerLab.com) that certify purity and quality.
• Take it with food. Research indicates fish oil is better absorbed when taken with a meal, especially one with some dietary fat.
• Store it smartly. Keep the bottle tightly sealed and away from heat and humidity, which can turn the oil rancid.
• Watch for interactions. Fish oil can interfere with blood thinners, blood pressure medications and other drugs. Always check with your doctor before adding a supplement, especially if you take prescription medications.

Even if you follow these recommendations, experts stress that eating actual fish a few times a week is always a better bet for long-term health than relying on a supplement, especially if it’s part of a healthy diet rich in fruits, vegetables, whole grains and healthy fats.

“What we’ve learned is when we just focus on one individual nutrient or one individual food, it never stands the test of time,” Lichtenstein says. “That’s because it’s the whole pattern (of what you eat) … that really makes the difference.”