A dose-response meta-analysis found that supplementation with omega-3 fatty acids between 2 and 3 grams daily was optimal for lowering blood pressure (BP), and that increased intake may be beneficial for individuals at higher risk. These findings were published in the Journal of the American Heart Association.

Publication databases were searched through May of 2021 for randomized controlled trials of docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) supplementation for lowering systolic or diastolic BP in adults. The investigators performed a 1-stage random-effects dose-response model to evaluate the optimal dose.

The overall sample size was 4973 individuals with aged on average between 22 and 86 years. Both men and women were included in 43 trials, 25 trials included only men, and 3 trials only included women. Most studies recruited individuals with hypertension (79%) and without hyperlipidemia (80%).

Interventions included fish oil, algal oil, purified fish oil ethyl esters, and dietary interventions. The most common controls were olive oil or vegetable oils.

A significant nonlinear (J-shaped) dose-response relationship for systolic BP (z, 3.87; P =.0001) and diastolic BP (z, 2.68; P =.0073) were observed. These relationships indicated that the optimal DHA plus EPA dose was 2 to 3 grams daily.

Systolic BP associated with a -2.61 (95% CI, -3.57 to -1.65) mm Hg change with 2 grams daily and -2.61 (95% CI, -3.52 to -1.69) mm Hg change with 3 grams daily. Diastolic BP associated with a -1.64 (95% CI, -2.29 to -0.99) mm Hg change with 2 grams daily and -1.80 (95% CI, -2.38 to -1.23) mm Hg change with 3 grams daily.

Among the subgroup of individuals with baseline systolic BP of 130 mm Hg or higher, DHA plus EPA supplementation had an approximately linear relationship with BP, indicating that increased supplementation resulted in a stronger reduction in BP. A similar trend was observed among the subgroup with hyperlipidemia and among individuals aged 45 years or older.

The study investigators did not observe an effect for type of supplementation.

The potential limitations of this analysis were the differing BP measurement techniques, the broad range of time the studies were conducted, and differing intervention strategies.

“The seemingly J-shaped associations between DHA plus EPA dose and BP reduction in many subgroups might help reform preventive strategies for reducing cardiovascular risks in the general adult population” the study authors noted. “However, individuals who are at high risk for developing cardiovascular diseases, such as those with hypertension, may be more responsive to the beneficial impacts of [omega-3 polyunsaturated fatty acid] intake on reductions in BP.”

Reference

Zhang X, Ritonja JA, Zhou N, Chen BE, Li X. Omega-3 polyunsaturated fatty acids intake and blood pressure: A dose-response meta-analysis of randomized controlled trials. J Am Heart Assoc. Published online June 1, 2022. doi:10.1161/JAHA.121.025071

A total of 71 trials published between 1987 and 2020 were included in this analysis. The studies were conducted in Europe (n=27), North America (n=25), Oceania (n=16), and Asia (n=3).