Omega-3 fatty acids and the heart: New evidence, more questions

My patients often ask me if they should try one supplement or another. Often my answer is equivocal, because for most supplements we just don’t have enough evidence to give a definitive answer.. This does not mean that a particular patient could not benefit from a specific supplement; it just means that I don’t have standardized research to guide my recommendations. Unfortunately, this remains true for omega-3 fatty acid supplements. The results of studies of omega-3 supplements have been inconsistent and have left doctors and patients wondering what to do next.

Omega-3 Fatty Acids Show Benefits in REDUCE-IT Trial, Gets FDA Approval

Two main omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are mainly found in fish and fish oil. Omega-3s in fish and fish oil have been recommended by the American Heart Association (AHA) for 20 years to reduce cardiovascular events, such as heart attacks or strokes, in people with existing illnesses cardiovascular disease (CVD). I have written and am a strong supporter of consuming omega-3s through diet, and sometimes through supplementation.

In the past year, I have prescribed an omega-3, sold under the brand name Vascepa, to my patients who are at high risk for cardiovascular disease, based on evidence of cardiovascular benefit. Vascepa contains purified EPA and its use is based on good clinical data from the REDUCE-IT trial. This study enrolled more than 8,000 patients with high cardiovascular risk and high blood triglyceride levels. They assigned half of the study participants to receive 2 grams of Vascepa twice a day, and the rest of the participants were assigned a placebo (a pill filled with mineral oil). The results showed a significant benefit of Vascepa over placebo. Vascepa reduced blood triglyceride levels, but more importantly, it reduced the number of heart attacks and strokes, the need for a cardiac stent procedure to open blocked arteries, and death.

A subsequent meta-analysis, which included data from more than 10 studies, found that omega-3 fish oil supplements reduced the risk of heart attack and death from coronary artery disease.

In December 2020, the FDA approved the use of Vascepa to reduce the risk of cardiovascular events in certain patients with or at high risk for CVD.

STRENGTH trial casts doubt on benefits of omega-3s

But a recent study has raised some questions. The STRENGTH essay, published in JAMA, examined a different formulation of omega-3 fish oil – a combination of EPA and DHA – to see if it would reduce cardiovascular risk as well. This study enrolled more than 13,000 patients who were randomized to receive either the combined EPA / DHA pill or the placebo (a pill filled with corn oil). The trial was terminated prematurely due to an interim analysis showing no difference between the two treatment groups.

We are not sure why the REDUCE-IT trial showed an omega-3 benefit, compared to the STRENGTH trial. One possibility is that the different results are due to the different drugs studied. REDUCE-IT investigated a purified formulation of high dose EPA, which resulted in higher levels of EPA. This was similar to the results of another trial, which also found that pure EPA reduced the risk of cardiac events. The STRENGTH trial tested a combination of EPA and DHA. No large study has ever evaluated the effects on cardiovascular outcomes of purified DHA alone, leaving us to wonder if DHA might counteract the benefits of EPA.

Where are we?

Back to my patients who want to know if they should take an omega-3 supplement. With the data available today, I would recommend a pure EPA supplement, or one that contains more EPA than DHA. But don’t stop there. Eat a heart-healthy diet, exercise regularly, and pursue other lifestyle changes that have been shown to benefit heart health. In the meantime, my colleagues and I are awaiting more definitive data on the usefulness of omega-3 fish oil, and who could benefit the most from it.

The post Omega-3 fatty acids and the heart: New evidence, more questions first appeared on Harvard Health Blog.

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Jothi Venkat

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