Trending Clinical Topic: Fish Oil

Ryan Syrek


November 27, 2020

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Findings from several studies investigating the relationship between omega-3 fatty acids and cardiovascular health were presented at the American Heart Association (AHA) Scientific Sessions 2020 virtual meeting and resulted in fish oil becoming this week's top trending clinical topic.

Primary results of the VITAL Rhythm trial found no evidence to support the use of marine-oil capsules or vitamin D3 for the prevention of atrial fibrillation (see Infographic below). In the large-scale, long-term, randomized, placebo-controlled trial, participants without a history of atrial fibrillation, cardiovascular disease, or cancer were randomly assigned to take a gram of omega-3 fatty acids, 2000 IU vitamin D3, or a placebo daily. No benefit in terms of atrial fibrillation occurrence was observed, and experts say that omega-3 fatty acids actually may have been associated with increased incidence.

The bad news for fish oil didn't stop with the VITAL trial findings. Results of the STRENGTH trial showed that a high-dose omega-3 fatty acid product had no positive effect on cardiovascular event rates. A product containing a high-dose combination of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) not only demonstrated no benefit, but it also was associated with more adverse effects in the active treatment arm of the study, with a higher rate of gastrointestinal symptoms and atrial fibrillation. Of note, the negative results of the STRENGTH trial stand in opposition to the positive results of the previous REDUCE-IT trial, which showed a 25% relative risk reduction in major adverse cardiovascular events with the high-dose purified EPA product icosapent ethyl. Interestingly, rates of atrial fibrillation were higher in those taking icosapent ethyl.

Yet another disappointing result was reported in the randomized OMEMI trial. Researchers found that a low-dose combination of EPA and DHA on top of standard care did not reduce major cardiovascular events or death in older patients who had had a previous acute myocardial infarction. Similar to what was seen in the STRENGTH and REDUCE-IT trials, the omega-3 fatty acid was associated with a nonsignificant increase in new-onset atrial fibrillation. The OMEMI trial results are particularly insightful for older populations, who are often excluded from clinical trials and whose cardiovascular event risk is high.

The degree to which fish oil has any cardiovascular benefit remains uncertain, although many physicians have strong opinions on the matter. As more evidence — either for or against its use — becomes available, omega-3 fatty acid is likely to remain a popular subject.

Read more about fish oil.


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