The Evidence on Fish Oil Supplements
Years of nutrition research have demonstrated that diets that are high in omega-3 fatty acids seem to be better for people’s cardiovascular health than diets with low levels of these substances, according to Donald Lloyd-Jones, MD, principal investigator for the Framingham Heart Study at Boston University School of Medicine and scientific lead for clinical research services for the American Heart Association. Other studies have also found that people with higher levels of EPA and DHA in their blood tend to be at lower risk for heart attacks, coronary heart disease, and other problems.
It’s no wonder, then, that people would take supplements with EPA and DHA in an effort to boost their heart health.
And omega-3s do a lot of crucial work in your body. They help form the structure of cell membranes, for example, and the body also uses them to form molecules that have a wide range of functions in the body’s cardiovascular system, immune system, and more. But though regular, nonfried fatty fish intake has been consistently associated with a reduced risk of heart-related death, coronary heart disease, and stroke, the evidence is less clear on the benefits of getting omega-3s from supplements alone. The pills, research suggests, may not really help the general population, though some people with certain existing cardiovascular problems might get some benefit.
One independent analysis of 86 randomized controlled trials, published in 2020, found that people who took a fish oil supplement did not have a lower risk of stroke or cardiovascular disease death compared with those who took a placebo pill or ate their usual diets. The researchers did find that people who took fish oil pills may be less likely to have a heart attack, but the difference was so slight that the researchers said it could not be conclusively attributed to the fish oil. The authors wrote that omega-3 supplements are “probably not useful for preventing or treating cardiovascular disease.”
Lloyd-Jones agrees. When it comes to the general population, he says, “We have not seen supplementation with omega-3 fatty acids reduce the risk of cardiovascular disease.”
Lloyd-Jones says that while earlier clinical trials of fish oil pills showed a more significant benefit for people with existing cardiovascular disease, more recent trials have not shown the same advantages. That could be in part because statins and other risk-reducing medications are now used routinely in patients with a past heart attack or other coronary heart events, he says. That would make any much smaller effects of the supplements difficult to detect.
And there is a potential downside: Some evidence suggests that for otherwise healthy people, regular use of omega-3 supplements might actually raise the risk of certain cardiovascular problems, like atrial fibrillation and stroke.
