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Rematch: EPA vs. DHA for cardiovascular risk factors

NERD #21 already examined the effect of EPA vs. DHA in very high doses. This randomized trial answers whether normal doses of either fatty acid could help inflammation and blood lipids.

Study under review: Effects of Eicosapentaenoic Acid and Docosahexaenoic Acid on Cardiovascular Disease Risk Factors: A Randomized Clinical Trial

Introduction

The medium-term effect of fish oil is well established for lowering blood triglyceride levels. High triglycerides are also known to raise the risk[1] of cardiovascular disease. However, in recent years, there’s been controversy[2] about whether fish oil is effective in preventing cardiovascular disease more generally. One recent meta-analysis[3] found no effect on cardiovascular disease itself, but (as shown in Figure 1) did find a decreased risk of death from cardiac causes in people with coronary heart disease who take fish oil.

Fish oil contains both EPA and DHA, raising the question of whether one may be more effective at promoting cardiovascular health. In NERD #21, Volume 1, “Fish oil showdown: anti-inflammatory effects of EPA vs. DHA” explored a study that compared the effects of EPA and DHA on inflammatory biomarkers and blood lipids in adults with abdominal obesity and low-grade inflammation. This research was an important contribution to the field, as no prior work has directly compared EPA and DHA. This is despite a growing body of evidence suggesting each has the potential to reduce inflammation and despite a meta-analysis[4] of 68 randomized controlled trials and 4,601 individuals showing both to have a significant impact on several inflammatory biomarkers.

Figure 1: Effect sizes of fish oil on outcomes in people with CVD

Reference: Wen et al. Nutr Metab Cardiovasc Dis. 2014 May.

Unfortunately, the study had two major limitations. First, it was conducted exclusively in men and women with abdominal obesity and low-grade inflammation, precluding generalizations to a healthy population. Second, the EPA and DHA doses were set at 2.7 grams per day, which is far greater than what is provided by common over-the-counter fish oil supplements that many individuals use for preventive therapy. These are commonly one-gram fish oil pills providing 200-300 milligrams of EPA and DHA. The current study sought to compare the effects of EPA and DHA on numerous cardiovascular disease risk factors, including blood lipids and inflammatory biomarkers, with doses frequently used in the real world by healthy adults.
The effects of low-dose EPA and DHA on cardiovascular disease risk factors such as blood lipids and inflammatory biomarkers in healthy adults is not well defined. The current study sought to pit real-world dosing of EPA against DHA to examine which may have a greater impact on cardiovascular disease risk factors in a healthy population.

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