Consuming omega-3 supplements or omega-3-rich food may be as effective as reducing sodium or alcohol, or increasing exercise for reducing blood pressure, says a new meta-analysis of 70 randomized controlled trials.
Compared with placebo, consumption of EPA and DHA omega-3s was associated with an average 1.52 mmHg and 0.99 mmHg reduction in systolic and diastolic blood pressure, respectively, according to data published in the American Journal of Hypertension .
The cardiovascular benefits were greater still for untreated hypertensive subjects, who experienced average reductions of systolic and diastolic blood pressure of 4.51 mmHg and 3.05 mmHg, respectively. About 60% of the US adult population is reported to have elevated blood pressure.
But the benefits were not limited to hypertensives, however, with normotensive subjects also experiencing beneficial reductions of 1.25 mmHg and 0.62 mmHg reduction in systolic and diastolic blood pressure, respectively.
‘Significant clinical impact’
“When measuring blood pressure, even small reductions can have a significant clinical impact,” said Dominik Alexander, PhD, from Exponent, Inc, and senior author of the study. According to Stamler, et. al., each 2 mm Hg reduction reduces stroke mortality by 6%, coronary heart disease mortality by 4% and total mortality by 3%.
Dr Alexander noted that a decrease in SBP of 1.25 mm Hg could prevent a pre-hypertensive from becoming hypertensive. “A decrease of 4.51 mm Hg in SBP among those with high blood pressure could help an individual avoid having to take medication to control blood pressure levels,” he added.
The findings were welcomed by Adam Ismail, executive director of the Global Organization for EPA and DHA Omega-3s (GOED), which commissioned the meta-analysis. "Results from this study build on a wealth of prior data indicating that EPA+DHA intake reduced the risk of cardiovascular events," said Ismail. “It is now well-established that EPA and DHA reduce triglycerides and blood pressure and even highly critical meta-analyses have found that they reduce cardiac death risk by 9%."
Dr Alexander and his co-authors from Exponent Inc. and Van Elswyk Consulting, Inc. examined the effect of EPA and DHA from omega-3-rich and -fortified foods and supplements on blood pressure, and selected only randomized clinical trials that exceeded three weeks in duration.
Data for 70 trials matched the criteria for inclusion, and crunching the numbers indicated significant benefits for both normo- and hyper-tensive people, with the greatest benefits for untreated hypertensives, they said.
The reductions observed for the untreated hypertensive people were equal to, and even exceeded, the reductions seen by other lifestyle changes. For example, studies with non-treated individuals with high blood pressure have shown that dietary sodium reduction reduces systolic blood pressure by 3.6 mmHg, physical activity by 4.6 mmHg and alcohol by 3.8 mmHg.
“These results are consistent with findings from Campbell et al. as well as other earlier meta-analyses,” wrote the authors. “Lowered systemic vascular resistance through changes in endothelial function is considered a primary mechanism by which EPA+DHA may lower blood pressure.
“Recent systematic reviews and a meta-analysis of RCTs found improved endothelial function in response to EPA+DHA, particularly among patients with risk factors for CVD, including hypertension, but not consistently among healthy young and middle-aged subjects. This observation may explain the greater response of unmedicated hypertensive subjects when compared with normotensive subjects in our meta-analysis.
“Collectively, the evidence from RCTs indicates that provision of [at least] 2g/d EPA+DHA may reduce both [systolic and diastolic blood pressure], with the strongest benefits observed among hypertensive individuals who are not on antihypertensive medication. In addition, a lower dose (between 1 and 2g/d) may reduce systolic but not diastolic blood pressure.
“From a clinical and public health perspective, provision of EPA+DHA may lower BP and ultimately reduce the incidence of associated chronic diseases,” they concluded.
Source: American Journal of Hypertension
Published online ahead of print, doi: 10.1093/ajh/hpu024
“Long-Chain Omega-3 Fatty Acids Eicosapentaenoic Acid and Docosahexaenoic Acid and Blood Pressure: A Meta-Analysis of Randomized Controlled Trials”
Authors: P.E. Miller, M. Van Elswyk, D.D. Alexander,