What’s the Skinny on Fish Oil? New Research Raises Questions About Omega-3 Supplements

In the wellness world, few things are equally as common and as confusing to swallow as advice about vitamins and supplements and whether they have any benefit. 

Research published last week in the journal BMJ Medicine looked at the risk-vs.-benefit profile of fish oil on heart health, suggesting from a years-long study that regularly taking fish oil may increase the risk of cardiovascular events, including atrial fibrillation and stroke, in people who didn’t have a high risk. 

In those who already had cardiovascular disease, the researchers found a benefit to taking fish oil supplements and how the disease progressed. 

Fish oil supplements may be the most common type of omega-3 supplement people can get over-the-counter. They’re often in capsule form, and people reach for them because some research has looked into omega-3 intake as potentially benefiting a variety of health concerns, including rheumatoid arthritis, cognition and even things like ADHD. 

But the fact that fish oil supplementation may not benefit heart health for the general population is “not a new issue, just a new paper on the issue,” Dr. Andrew Freeman, a cardiologist with National Jewish Health in Denver, told CNET.

He added that over-the-counter fish oil supplements are different from the “highly purified” forms of fish oil, including Lovaza and Vascepa, that people can get from their doctor with a prescription to lower triglycerides. (High triglycerides contribute to cardiovascular risk.) 

While far from the final word on the benefits and risks of omega-3 supplements (there were limitations to this study, including the big fact people self-reported fish oil intake so this research doesn’t reflect dosage), it dredges up questions that continue to bump up against supplement recommendations in general, like the fact they’re not regulated for safety or effectiveness by the US Food and Drug Administration, and the fact we’re meant to get the majority of our nutrients from food and diet. 

Certain eating patterns that focus largely on plant-based foods full of healthy fats, lean proteins and some food-based fish oil sources (including diets like the Mediterranean diet) continue to be linked to positive health findings. Those diets may be rich in omega-3 fatty acids and other nutrients, but it’s proven difficult to replicate those benefits in supplement form. 

“There is not a lot of evidence for omega-3 supplements in general,” Dr. Navya Mysore, a primary care physician based in New York, said in an email. If someone is interested in adding one to their routine for whatever health concern, she said, it’s a good idea to check in with a doctor before “making a personalized decision for yourself.”

Read more: Omega-3 Rich Foods Offer Many Benefits for Heart, Hearing and Overall Health

What did the study find? Strengths and limitations

The BMJ Medicine study followed more than 400,000 participants, ages 40 to 69, enrolled in the UK Biobank study, following their health events and lifestyle and dietary factors they reported, including whether they regularly took fish oil supplements, their regular food consumption and more. 

After years-long follow-up, researchers found that fish oil supplementation in people who already had cardiovascular disease was beneficial, but in the general population (i.e. those without cardiovascular disease), regularly taking fish oil was linked to increased risk of first-time heart disease and stroke. 

Strengths of the study are that it is large and it was able to track incidences of heart events. Researchers also collected details on some factors that can influence heart health, like smoking, binge drinking and general diet. However, it “did not consider behavioral changes in populations with different cardiovascular profiles,” the researchers wrote. It also can’t account for all health-affecting behaviors that may influence someone’s wellness choices, which are notoriously tricky to separate and pin down to one cause or effect. 

Also, most participants in the study were white, the researchers noted, so whether the same link can be drawn to people of other races is unknown from this study alone. And importantly, it did not account for the dosage of fish oil people were taking or specific brands or types. 

So… should people stop taking omega-3 supplements?

The latest findings should not make you panic and feel that your omega-3s or fish oil pills are heart problems in a bottle; as the study’s authors noted, more research is needed on the link between cardiovascular events and fish oil, and it comes on the tail of ongoing research into the comprehensive, complicated tie between omega-3s and different health benefits when they come in supplement form. At least for the general population, much of it has been conflicting or inconclusive.

This study alone isn’t enough to definitively sway the fish oil benefits argument, according to Dr. Gregory Katz, a cardiologist with NYU Langone. 

“To change clinical practice, only a randomized trial actually lets you see cause and effect,” Katz said in an email. “A study like this doesn’t tell you whether the fish oil caused the irregular heartbeats.” 

But, he said, “There’s been a signal in some of the clinical trials on high-dose omega-3 supplements — that there may be an increased risk of an irregular heartbeat called atrial fibrillation,” which does increase the risk of stroke. 

When asked whether vegan or vegetarian omega-3 supplements would be better — those that come from ALA instead of DHA and EPA, the evidence is also murky, since ALA is a “precursor in the body to DHA and EPA, which are the active omega-3s,” Katz said, adding that the way it’s converted to active omega-3s isn’t as efficient and it may be “not all that useful.”

So all of this circles back to the same advice: Get your omega-3s (and all other nutrients) from your food when possible. If that’s not possible, talk with your doctor about starting a dietary supplement or using additional vitamins. Because people may be interested in taking omega-3s for different health reasons beyond heart health, you should speak with someone who understands your health history so you can weigh your risks and benefits. 

In a large summery last updated in 2023, which looked at available studies on omega-3s and omega-3 supplements for a whole scroll of health conditions including cardiovascular disease, the National Institutes of Health Office of Dietary Supplements concluded that “consuming fish and other types of seafood as part of a balanced diet promotes heart health, especially when the seafood is consumed in place of less healthy foods.” But evidence of protective heart-health benefits of supplements is stronger in people with existing disease. 

The latest findings do drive home some much-needed nuance for supplements, though.

“Not everybody’s the same,” Freeman said of the latest fish oil study. “Not all drugs are the same, and what may seem benign may not always be the case.”