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Just 3g of omega-3 fatty acids daily might lower BP – Chinese meta-analysis

About 3g daily of omega-3 fatty acids, consumed in foods or supplements, appears to be the optimal daily dose to help lower blood pressure, according to a research review by a team from a university in China.

The findings were published in the peer-reviewed Journal of the American Heart Association.

Omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are typically found in fatty fish, such as salmon, tuna, sardines, trout, herring and oysters. Some people also take combined DHA and EPA in supplements.

While some studies suggest that consumption of omega-3 fatty acids may lower blood pressure, the optimal dosage needed to lower blood pressure has not been clear. The US National Institutes of Health (NHI) has established an adequate intake of omega-3 fatty acids for healthy people at 1.1- 1.6g daily, depending on age and sex.

“According to our research, the average adult may have a modest blood pressure reduction from consuming about 3g a day of these fatty acids,” said study author Dr Xinzhi Li, assistant professor and programme director of the School of Pharmacy at Macau University of Science and Technology in Macau, China.

Researchers analysed the results of 71 clinical trials from around the world published from 1987 to 2020. The studies examined the relationship between blood pressure and the omega-3 fatty acids DHA and EPA (either individually or combined) in people aged 18 and older with or without high blood pressure or cholesterol disorders. There were nearly 5,000 participants combined, ranging in age from 22 to 86 years. Participants took dietary and/or prescription supplement sources of fatty acids for an average of 10 weeks.

The analysis found:
• Compared with adults who did not consume EPA and DHA, those who consumed between 2g and 3g daily of combined DHA and EPA omega-3 fatty acids (in supplements, food or both) had reduced systolic (top number) and diastolic (bottom number) blood pressure by an average 2 mm Hg.
• Consuming more than 3g of omega-3 fatty acids daily may have added blood pressure-lowering benefit for adults with high blood pressure or high blood lipids:
• At 3g a day of omega-3s, systolic blood pressure (SBP) decreased an average of 4.5 mm Hg for those with hypertension, and about 2 mm Hg on average for those without.
• At 5g a day of omega-3s, SBP declined an average of nearly 4 mm Hg for those with hypertension and less than 1 mm Hg on average for those without.
• Similar differences were seen in people with high blood lipids and among those older than age 45.

About 140g of Atlantic salmon provides some 3g of omega 3 fatty acids. A typical fish oil supplement contains about 300mg of omega-3s per pill, but doses vary widely.

“Most of the studies reported on fish oil supplements rather than on EPA and DHA omega-3s consumed in food, which suggests supplements may be an alternative for those who cannot eat fatty fish, such as salmon, regularly,” Li said. “Algae supplements with EPA and DHA fatty acids are also an option for people who do not consume fish or other animal products.”

The US Food and Drug Administration (FDA) announced in June 2019 that it did not object to the use of certain health claims that consuming EPA and DHA omega-3 fatty acids in food or dietary supplements might reduce the risk of hypertension and coronary heart disease. However, it noted that the evidence was inconclusive and highly inconsistent.

“Our study supports the FDA guidance that EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease by lowering high blood pressure, especially among people already diagnosed with hypertension,” he said. “However, while our study may add a layer of credible evidence, it does not meet the threshold to make an authorised health claim for omega-3 fatty acids in compliance with FDA regulations.”

Limitations of the review include differences in how blood pressure was measured, and whether the studies examined omega-3 intake from supplements or diet, which may affect the strength of the conclusions.

The American Heart Association recommends eating two servings of fish per week (particularly fatty fish like salmon) as part of a heart-healthy diet.

Study details

Omega‐3 Polyunsaturated Fatty Acids Intake and Blood Pressure: A Dose‐Response Meta‐Analysis of Randomised Controlled Trials

Xin Zhang, Jennifer A. Ritonja, Na Zhou, Bingshu E. Chen, Xinzhi Li.

Published in the Journal of the American Heart Association on 1 June 2022

Abstract

Background
Current evidence might support the use of omega‐3 fatty acids (preferably docosahexaenoic acid and eicosapentaenoic acid) for lowering blood pressure (BP), but the strength and shape of the dose‐response relationship remains unclear.

Methods and Results
This study included randomised controlled trials published before 7 May 2021 that involved participants aged ≥18 years, and examined an association between omega‐3 fatty acids (docosahexaenoic acid, eicosapentaenoic acid, or both) and BP. A random‐effects 1‐stage cubic spline regression model was used to predict the average dose‐response association between daily omega‐3 fatty acid intake and changes in BP. We also conducted stratified analyses to examine differences by prespecified subgroups.
Seventy‐one trials were included, involving 4,973 individuals with a combined docosahexaenoic acid+eicosapentaenoic acid dose of 2.8 g/d (interquartile range, 1.3 g/d to 3.6 g/d). A nonlinear association was found overall or in most subgroups, depicted as J‐shaped dose‐response curves. The optimal intake in both systolic BP and diastolic BP reductions (mm Hg) were obtained by moderate doses between 2 g/d (systolic BP, −2.61 [95% CI, −3.57 to −1.65]; diastolic BP, −1.64 [95% CI, −2.29 to −0.99]) and 3 g/d (systolic BP, −2.61 [95% CI, −3.52 to −1.69]; diastolic BP, −1.80 [95% CI, −2.38 to −1.23]). Subgroup studies revealed stronger and approximately linear dose‐response relations among hypertensive, hyperlipidemic, and older populations.

Conclusions
This dose‐response meta‐analysis demonstrates that the optimal combined intake of omega‐3 fatty acids for BP lowering is likely between 2 g/d and 3 g/d. Doses of omega‐3 fatty acid intake above the recommended 3 g/d may be associated with additional benefits in lowering BP among groups at high risk for cardiovascular diseases.

 

JAHA article – Omega‐3 Polyunsaturated Fatty Acids Intake and Blood Pressure: A Dose‐Response Meta‐Analysis of Randomised Controlled Trials (Open access)

 

See more from MedicalBrief archives:

 

Even without weight loss, Nordic diet lowers cholesterol and blood sugar

 

Omega-3 link to improved life expectancy and cardiovascular outcomes — Two studies

 

Eating fish associated with significant health benefits — Pooled analysis

 

Omega 3 supplements not protecting against heart disease and stroke – Cochrane review

 

 

 

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