6 min read
Key Points
For years, fish oil supplements were lauded for its wide range of health benefits ranging from thicker hair to a stronger heart.There were several issues with the research findings, including extrapolating data from the benefits of diets rich in oily fish to supplementationNew research suggests fish oil supplements could potentially worsen brain health and increase the risk of stroke.Nutrition experts say a supplement is not necessary if you eat fatty fish twice a week.
AT ONE POINT it appeared that fish oil supplements were going to save us all. Research on the dietary supplement kept finding bigger and better findings. Fish oil helped with heart disease, made you smarter, as well as improved dry eyes and arthritis. Scientists even found fish oil gave you thicker, lusher hair and more healthy-looking nails. Basically if you weren’t taking fish oil in the 2000s—what were you doing?
Now if there was any other “wonder” product that sounded like a late-night informercial, people would be quick to call it snake oil, not fish oil. But there was science! It seemed hard to argue with fish oil proponents when they had clinical trial data and studies ready to back up the claims.
But like Ayds diet candy, fish oil did not age well.
Turns out, the research that propped up fish oil supplements later turned out to be not so true. Supplement companies conflated study results that showed the benefits of the oil from fish—as in the food—with their fish oil supplements. There is a difference but more on that below.
Despite the 180 in nutrition advice, fish oil supplements are still a staple in many people’s medicine cabinet. So let’s revisit fish oil supplements—and what the science has to say about their supposed benefits.
What Exactly Is Fish Oil?
NOT TO BE obvious, but it’s the oil from fish. More specifically, it’s omega-3s eicosapentaenoic acid (EPA) though largely docosahexaenoic acid (DHA). These fatty acids make up the oily nature of fish, some in greater presence in certain varieties. Salmon and mackerel are high in omega-3 fatty acids and are considered “oily” fish. Cod and tilapia are lower in omega-3s. Shellfish have omega-3s too.
In supplement form, fish oil is extracted from fish and shellfish that contain omega-3 fatty acids, sometimes krill, usually anchovies. (Yes, the anchovies Americans love to hate.)
What Is Fish Oil Good For?
FIRST, JUST KNOW that we’re talking about the omega-3 fatty acids found in seafood here—not supplements, yet.
Fish oil—from seafood—has a wide variety of well-studied benefits.
“There’s some pretty significant evidence that it’s important to have enough omega-3s for heart health, brain health, eye health, joint health—all of those areas rely on having plenty of omega-3s in your diet,” says Brian St. Pierre, MS, RD, CSCS, director of nutrition at Precision Nutrition.
BrianAJackson//Getty Images
What Are Fish Oil Supplements Good For?
THERE’S A VERITABLE sea of studies of fish oil and fish oil supplements out there. That’s actually a great thing. Unlike many other supplements, research can help build a scientific consensus. And while we’re not quite at consensus status for fish oil supplements, we’re getting closer in some areas.
Here’s where the research stands now.
Fish Oil Supplements and Heart Health
One of the most well-studied areas for fish oil supplementation is heart health. Many studies suggest that fish oil supplements have cardioprotective benefits. (Cardiovascular health claims were the most common in a study of 255 fish oil supplements published in JAMA Cardiology.) High-dose fish oil supplements are even available by prescription to reduce high triglycerides—fats that circulate in the bloodstream and increase heart disease and stroke risk.
Still, research continues to turn up new questions.
In a study published in BMJ Medicine, researchers found that fish oil supplements were associated with an increase in risk of stroke and atrial fibrillation in healthy people. However, in people with existing heart disease, fish oil was linked to a reduced risk of progression to bigger problems.
Another study published in the journal Nutrition showed that people who supplemented their diets with fish or fish oil supplements for a year experienced reductions in pro-inflammatory blood markers. But the biggest benefits were found in people who had previously eaten fish lessthan once a month.
Will those changes reduce your risk of diseases or help you avoid new ones? That’s still being sorted out.
Just a reminder from nutrition experts that fish oil supplements should never replace your statin for high cholesterol. Statins work better than fish oil or other common supplements for reducing cholesterol, according to a study published in the Journal of the American College of Cardiology.
Fish Oil Supplements and Arthritis
In a study review published in the Journal of Orthopaedic Surgery and Research, researchers found that supplementing with omega-3s relieved arthritis pain and improved joint function compared to placebo. The researchers speculated the reason could be from fatty acids reducing inflammation that break down cartilage.
Though here exists conflicting research too.
Another study found that data on dietary intervention of omega-3 supplementation in patients with arthritis is “limited”—meaning that it’s tough to draw conclusions from the existing science.
Are you seeing a pattern here?
Fish Oil Supplements and Eye Health
There’s not much research in this particular space. One study review published in Acta Opthalmologica found people with dry eyes taking fish oil reported an improvement in symptoms. Clinical tests, however, showed no difference.
The American Academy of Ophthalmology notes that using fish oil supplements is “outdated advice” and “no strong evidence that this is true.” Beyond the lack of scientific evidence, the organization warns that fish oil supplement brands vary in dosage and quality, making it difficult to truly know its benefits.
Fish Oil Supplements and Brain Health
At one point in time, fish oil was considered a shortcut to making you smarter. The research does show potential in improving brain health—but experts wouldn’t go so far to call it neuroprotective.
A study review published in the journal Cureus suggests that fish oil supplements can boost learning, memory, cognitive performance, and brain blood flow. Another study published in GeroScience showed that people who took fish oil had a slight (7 percent) reduced risk of developing dementia. Most concerning, however, is a 2026 study that found fish oil supplements may slow brain recovery after mild head injuries.
The idea that fish oil supplements help with mental health is also not so solid.
In a study published in JAMA, people who took omega-3 supplements for an average of 5.3 years were slightly more likely to develop depression or depressive symptoms than those who took placebos.
“The science isn’t quite there if you’re looking at things like mood improvement, like if somebody is truly diagnosed with a mental health disorder, such as major depression,” says LesLee Funderburk, PhD, RD, CSSD, CSCS, associate professor in nutrition sciences at Baylor University’s Robbins College of Health and Human Sciences. In other words, fish oil isn’t a substitute for mental health medication.
Experts Say This Is The Only Time to Take A Fish Supplement
DO YOU EAT fatty fish twice a week or more? If not, a fish oil supplement might benefit you, says St. Pierre. Any time you eat a serving of fatty fish, you can skip the supplement that day and the next few days.
A dose of one to two grams of EPA and DHA per day is likely safe and beneficial, without requiring you to swallow more than one to three pills a day, St. Pierre explains.
Choose a product independently verified by NSF, USP, ConsumerLab, or Informed Choice for purity and quality. Then, read the label closely—some products combine fish oil and other nutrients like vitamin D or vitamin K. You could accidentally overdo it when combining one of these varieties with other supplements containing the same nutrients.
Of course, before starting a new supplement, chat with your doctor or pharmacist. This is especially important if you take a blood thinner because fish oil can also have anticoagulating properties, especially at high doses. If you have a fish allergy, ask about alternatives like krill oil or algae oil.
One more thing: Don’t bother with eggs or milk with added DHA or EPA. The extra cost isn’t worth the minimal benefit. “The amounts that are present in products like that are too low,” says Dr. Funderburk. “There’s no therapeutic effect that’s going to occur from using those products during the week.”
Related Stories
Julie Stewart is a writer and content strategist whose work has also appeared in Health, and Women’s Health, Everyday Health, Vice, and Shape.