New Study Finds Hidden Risks of Fish Oil Supplements, Including Heart Issues
Sarah Cherry
Updated on February 22, 2026
Not everyone gets all the nutrients they need naturally, which is why so many of us turn to supplements. Fish oil, which contains omega-3 fatty acids that are said to have anti-inflammatory properties and reduce pain, is one of the most common go-to's. But while the benefits of taking supplemental fish oil have long been debated, new research identifies potentially serious hidden health risks, including heart issues and stroke.
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Fish oil is one of the most commonly used dietary supplements in the U.S., according to the National Institutes of Health (NIH). A 2023 report revealed that many adults—especially those over the age of 60—take these supplements for their heart health, despite clinical trials showing no sign of cardiovascular benefit from fish oil.
Now, new research suggests that fish oil may not just be useless for your heart health—it could actually harm it.
A study published May 21 in the BMJ Medicine journal analyzed data from over 415,000 people ages 40 to 69 in the U.K. who were observed for an average of 12 years. Of these people, nearly one-third said they regularly took fish oil supplements.
Researchers found that regular use of fish oil supplements in people without prior heart issues was associated with a 13 percent higher risk of developing atrial fibrillation. Also known as AFib or AF, atrial fibrillation is an irregular heartbeat or arrhythmia that "can lead to blood clots, stroke, heart failure and other heart-related complications," per the American Heart Association (AHA).
The study also concluded that regular use of fish oil supplements for people without prior heart issues was associated with a 5 percent heightened risk of stroke in particular.
"Studies over the last 10 years have not been very positive for over-the-counter fish oil," Andrew Freeman, MD, a cardiologist and the director of cardiovascular prevention and wellness at National Jewish Health in Denver, who was not involved in the study, told CNN. "Fish oil was either having no benefit or in some cases it may harm, such as with stroke and AFib."
RELATED: 12 Supplements You Should Never Take Together, Medical Experts Say.
In fact, Freeman said the use of OTC fish oil supplements "is very seldom recommended … and yet that's what most people take."
Most experts, including Alzheimer's preventive neurologist Richard Isaacson, MD, instead advise that people try getting their omega-3 fatty acids from food sources, such as sardines, wild-caught salmon, lake trout, mackerel, herring, and albacore tuna, CNN reported.
"We [also] recommend testing for omega-3 fatty acid levels—there are finger-prick tests you can buy online which are accurate—and then you should continue to test," Isaacson, who was not involved in the study, added. "You don't want to take fish oil if you don't need it."
If you do have to resort to OTC fish oil supplements, it's important to consider the freshness of the fish oil, so "buying from an online or retail superstore, such as Amazon or Costco, isn't the best idea," Isaacson told CNN.
"We recommend buying it from only a handful of reputable companies, and from their specific website," he explained. "The difference in quality between fish oil stored in a hot warehouse that's close to expiration and fish oil that's recently been produced, sent directly from the company, and kept in the home refrigerator is night and day."
Best Life offers the most up-to-date information from top experts, new research, and health agencies, but our content is not meant to be a substitute for professional guidance. When it comes to the medication you're taking or any other health questions you have, always consult your healthcare provider directly.
Kali Coleman Kali Coleman is a Senior Editor at Best Life. Her primary focus is covering news, where she often keeps readers informed on the ongoing COVID-19 pandemic and up-to-date on the latest retail closures.Read moreFiled UnderHealth Advice • Medicine • News • ScienceSources referenced in this article- Source: NIH: Omega-3 Fatty Acids
- Source: BMJ Medicine: Regular use of fish oil supplements and course of cardiovascular diseases: prospective cohort study
- Source: American Heart Association: What is Atrial Fibrillation?
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