A dose-response meta-analysis of randomized controlled trials on omega-3 polyunsaturated fatty acids (PUFAs) and blood pressure (BP) has shown that specific doses of around 3 grams are optimal for lowering blood pressure in the general population.
While scientific evidence has shown that consuming omega-3 fatty acids in food or dietary supplements may help reduce the risk of high blood pressure, the optimal quantities of the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) have never been established. In addition, the strength and shape of the dose-response correlation still need to be determined.
For example, the Japan Eicosapentaenoic Acid Lipid Intervention Study linked EPA intake with a lower risk of major vascular events. However, previous meta-analyses looking at the connection between omega-3 PUFA intake and blood pressure could not identify a significant dose-response relationship, or showed conflicting trends. This may have been because they used pool meta-regression or grouped categories of exposure into separate meta-analyses, which means they didn’t examine the correlations among effects at different dose levels.
This study, conversely, aimed to more precisely determine the dose-response effect of either DHA, EPA, or both on BP in the general population, as well as relevant subgroups. Researchers analyzed the results of 71 clinical trials from around the world published between 1987 and 2020 examining the relationship between BP and DHA and EPA in almost 5,000 individuals aged 22 to 86 years. The study participants either had or did not have high blood pressure or a cholesterol disorder, and took dietary and/or prescription omega-3 dietary supplements for an average of 10 weeks.
The analysis found that:
- Compared with adults who did not consume EPA and DHA, those who had an intake of 2-3 grams per day of combined DHA and EPA of any kind had reduced systolic and diastolic blood pressure by an average of 2mm Hg.
- For adults with high blood pressure or high blood lipids, there may be more blood pressure-lowering benefits when over 3 grams of omega-3 PUFAs are consumed.
- For those with hypertension, 3 grams may help decrease systolic blood pressure by 4.5 mm Hg on average, and by an average of 2mm Hg for adults with no hypertension.
- If the dose was increased to 5 grams daily, systolic blood pressure decreased by nearly 4 mm Hg for people with hypertension and less than 1 mm Hg for those without hypertension, on average. Similar changes were noted in people with high blood lipids and those aged 45 and above.
Limitations of this review include variation in how blood pressure was measured in the research analyzed, and whether the source of omega-3s came from supplements or food. However, this study supports the FDA guidance that EPA and DHA omega-3 PUFAs may help reduce the risk of coronary heart disease by lowering high BP, particularly among those who have already been diagnosed with hypertension.