New meta-analysis adds credence to positive blood pressure outcomes associated with omega-3s

30-Aug-2022 - Last updated on 30-Aug-2022 at 12:27 GMT

A comprehensive new meta-analysis underpins previous evidence and adds further credence to the positive impact of omega-3 fatty acids (n-3 PUFAs) on high blood pressure (BP).

The US Food & Drug Administration (FDA) officially acknowledged in 2019 the benefits of omega-3 on BP and authorised the use of ‘qualified health claims’ on products based on the ‘credible evidence’ of 70 studies commissioned by the Global Organisation for EPA and DHA Omega-3s (GOED).

The industry had sought an ‘authorised health claim’ (that requires ‘significant scientific agreement’) but the FDA is prudent in awarding the latter standard and these latest findings are unlikely to make any significant difference, according to GOED, Vice President of Regulatory and Scientific Affairs, Harry Rice.

“I think the FDA is so concerned about having to reverse a decision that it now defaults to qualified health claims. Since 1990, the FDA has authorized 12 health claims,” he said.

While there are no additional findings in the current meta-analysis, which is published in Frontiers in Nutrition, said Dr Rice, it provides important “corroborating evidence that strengthens an existing strong body of scientific evidence can't be discounted”.

“The FDA has been very clear that meta-analyses can be useful in the Agency's review, but a meta-analysis on its own cannot support a health claim relationship,” he added.

Statistically significant

The current meta-analysis involved material sourced from PubMed, Scopus, Embase, Web of Science, and Google Scholar databases, which was screened by two independent reviewers. Other researchers provided further input where disagreements arouse.

The 10 studies examined the impact of n-3 PUFAs on BP of 6,337 subjects aged 34 to 55 years. Average dosage across the studies was 2.2-6g per day with a duration of between four to 29 weeks. In total, researchers assessed 131 trials.

Hypotensive effects

Based on the mean age of subjects, analyses revealed that n-3 PUFAs among participants with 45 years and over had the most improving effect on SBP and DBP levels compared with younger participants.

“N-3 PUFAs may exert its hypotensive effects by several mechanisms. N-3 PUFAs may control the caveolae composition resulting in increased nitric oxide synthase,” the authors wrote.

They also note that short-term intake (up to 10 weeks) was more effective at decreasing SBP than long-term supplementation.

Omega-3 fatty acids promote hypotension by increasing vasodilator mediators like prostacyclin, inhibiting vasoconstrictors, such as thromboxane, they explained.

“Furthermore, hypotensive property of n-3 PUFAs may be the result of its ability to significantly reduction of TC and LDL-C,” they wrote.

There was, however, significant heterogeneity in responses in relation to subject age, study population, duration, sample size and dosage, the authors point out.

Reduced mortality

Even a slight reduction in BP can help prevent fatal illnesses associated with hypertension, and especially cardiovascular disease (CVD), the authors said.

Every 1mmHg decrease in SBP has the potential to reduce vascular mortality by nearly 2.5% in some cases, while several studies indicate n-3 PUFAs reduce CVD risk factors by improving inflammation, lipid, glycaemic profile, and decreasing body mass index (BMI), they said.

“Consequently, n-3 PUFAs can be considered as an effective and without life-threatening side effects agent in control of BP.”

They comment that daily supplementation with 2,000mg or more of EPA appears to be sufficient to decrease both DBP and SBP by 1.95 and 2.98 mmHg, respectively, findings showed.

“While the magnitude of the detected effect seems small, it appears to be both clinically and statistically significant,” the authors wrote.

“The BP lowering effect of n-3 PUFAs might be ascribed to enhancements of endothelial and smooth muscle function together with lowered systemic vascular resistance.”

Adjuvant therapy

The meta-analysis provides a comprehensive summary of broad evidence on the potential of n-3 PUFAs in the management and treatment of hypertension, said the authors.

Confounding elements to consider include different background diets and health statuses, subject heterogeneity, and proportion of n-6 PUFAs, which may also help reduce risk factors for CVD. They note that most trials in the meta-analysis included participants with metabolic disorders, hypertension, and type-2 diabetes mellitus (T2DM).

However, they added: “There is sufficient evidence for n-3 PUFAs to elicit helpful effects on blood pressure. Consequently, supplementation with n-3 PUFAs may be a useful adjuvant therapy in hypertensive patients.”

Source: Frontiers in Nutrition
Published online August 18, 2022 : doi: 10.3389/fnut.2022.985451
“The beneficial effects of omega-3 polyunsaturated fatty acids on controlling blood pressure: An umbrella meta-analysis”
Authors: V. Musazadeh, et al.