June 9, 2022 -- About 3 grams of an omega-3 fatty acid, either in the form of supplements or food, may reduce blood pressure, a new study suggests.

The findings show a substantial reduction in blood pressure for people who added a moderate amount of omega-3 fatty acids to their diet, particularly eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) combined, in doses of 2 to 3 grams per day, reported Xin Zhang, PhD, of Macau University of Science and Technology in Taipa, Macau, China, and colleagues.

This report expands on past research by including more recent studies, and uses a novel statistical method, the study authors noted.

"An optimal dose of omega-3 fatty acids is potentially needed for blood pressure control in the general population, but individuals who are at high risk of developing cardiovascular diseases may benefit from higher doses," the researchers concluded.

Prior research on omega-3 fatty acids over the last 25 years has shown conflicting results, says Srihari S. Naidu, MD, professor of medicine at New York Medical College in Valhalla, NY, who was not involved in the study.

"The most recent large trials, two of them … showed conflicting results, and more importantly they also showed that there may be an increased risk of bleeding and other complications such as [an irregular heartbeat]," Naidu says.

"Most cardiovascular professionals such as myself are a little bit averse to using these medications especially because we do have an aging population that has [irregular heartbeat] and bleeding tendency, especially if they have had stents or other cardiovascular procedures,” he says.

The meta-analysis – which is essentially a pooled analysis of similar studies to look for trends -- was based on 71 randomized controlled trials including 4,973 participants. The trials were selected if they were published prior to May 7, 2021, analyzed the link between blood pressure and various omega-3 fatty acids, like DHA, EPA, or both, and had study participants who were 18 years of age or older.

The optimal intakes associated with reductions in both systolic and diastolic blood pressure were seen with "moderate doses," the researchers said , between 2 grams per day.

But going over the  recommended 3 grams per day of omega-3 fatty acid consumption was not associated with other benefits, especially in people with normal blood pressure levels, they found.

Notably, further analysis showed that elderly people, those with high blood pressure and high cholesterol had better responses with higher doses.

The results were published online in the Journal of the American Heart Association on June 1.

‘Not Entirely Novel,’ but ‘Robust’

"Although these findings are not entirely novel, they are robust and provide insights into the long‐standing debate on the role of [EPA+DHA omega-3s] in modifying cardiovascular risk," write Marc George, MRCP, with the Queen Mary University of London, and Ajay Gupta, MD, with the William Harvey Research Institute, in the United Kingdom, in an editorial. Despite uncertainty around conflicting trial results over the years, they noted, "pooled data suggest a net modest benefit effect of [omega 3s], particularly on cardiovascular mortality in patients at high risk and with raised [blood fats]."

Results of this paper show that taking omega-3 PUFAs is associated with a blood pressure lowering effect, "and a dose of 2 to 3 [grams] appears to be optimal," they write.

"Given the modest effect on [blood fats], this BP‐lowering impact together with their other … effects are likely the missing link to explain the cardiovascular risk reduction seen in [past studies]."

But further randomized trials are required to "resolve the remaining questions …. Therefore, [omega 3s] are still not fully ready for prime time, and physicians should keep an open mind on these compounds with acute awareness toward of the mixed evidence base and the potential risks of increased [irregular heartbeat] and bleeding when prescribing."