CATrends: Fish Oil Supplements Marketed to Support Heart Health

Decades of research has shown that eating fish high in omega-3 fatty acids is good for your heart and may even prevent heart disease, the leading cause of death in the U.S. But can you get the same cardiovascular benefits from a fish oil supplement?

Marketers of fish oil supplements seem to think so, claiming that their products support “heart health” or a “healthy heart” and may even reduce the risk of coronary heart disease.

The marketing appears to be working: According to a recent study, one in five U.S. adults over 60 take a fish oil supplement, often for heart health. But do the products themselves work?

“While eating fish promotes [a] healthy heart, taking fish oil capsules does not,” alleges a lawsuit filed against the makers of Nature Made fish oil supplements in January.

The lawsuit cites “overwhelming evidence” that it claims demonstrates that fish oil or omega-3 supplements do not promote heart health, including “multiple randomized trials” that tested the products against placebos and found no evidence of any heart-health benefits.

Since January, lawsuits have also been filed against the makers of Nordic Naturals, Nature’s Bounty and Spring Valley fish oil supplements, with the same two law firms filing all the complaints except for the Spring Valley lawsuit, which is the most recent and states:

The supplement industry, anecdotal evidence and earlier studies have often promoted these [heart-health] benefits. Once a narrative becomes deeply embedded in popular culture, it can be difficult to change, even when new evidence emerges.

The lawsuits against Nordic Naturals, Nature’s Bounty and Spring Valley also cite potential health risks connected to the use of fish oil supplements that aren’t disclosed in the marketing, including the increased risk of atrial fibrillation.

Why don’t fish oil supplements work, according to these lawsuits? The answer may have something to do with the manufacturing process. Several of the complaints link to a 2023 blog published by Harvard Medical School, which states:

[M]any widely used fish oil supplements are produced through an industrial process that leaves the omega-3 fatty acids vulnerable to uncontrolled heat and oxygen, says [Preston] Mason [a researcher who studies omega-3 fatty acids]. “This results in the oxidation of these highly unsaturated fatty acids, with a consequent loss of any biological benefit,” he says, adding that multiple laboratory tests on dozens of products have confirmed these findings.

The lawsuits do not explain how using fish oil supplements may lead to an increased risk of atrial fibrillation, given this “loss of any biological benefit.”

All of the lawsuits are pending.

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