05.02.16
Although many randomized controlled trials (RCTs) have examined the effects of omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on blood pressure (BP) and vascular function, the majority have used doses of EPA+DHA of greater than 3 grams per day, which some researchers claimed is unlikely to be achieved by dietary manipulation.
The objective of this study, published in the Journal of Nutrition, was to examine, by using a retrospective analysis from a multicenter RCT, the impact of recommended EPA+DHA intakes achievable through diet on systolic and diastolic BPs and microvascular function in adults in the U.K.
In a double-blind, placebo-controlled trial, healthy men and women (n = 312) consumed a control oil or fish oil (FO) providing 0.7 or 1.8 g EPA+DHA/d, in random order, for 8 weeks. Fasting BP and microvascular function (using laser Doppler iontophoresis) were assessed and plasma collected for the quantification of markers of vascular function. Participants were retrospectively genotyped for the endothelial nitric oxide synthase (eNOS) rs1799983 variant.
No effects of omega–3 fatty acid treatment or any treatment × eNOS genotype interactions were evident in the group as a whole for any of the clinical or biochemical outcomes, according to study results. Assessment of response according to hypertension status at baseline indicated a significant (P = 0.046) FO-induced reduction (mean: 5 mm Hg) in systolic BP, specifically in those with isolated systolic hypertension (n = 31). No dose response was observed.
Researchers concluded these findings indicate that in adults with isolated systolic hypertension, daily doses of EPA+DHA as low as 0.7 g showed clinically meaningful BP reductions, which, at a population level, could be associated with lower cardiovascular disease risk. Confirmation of findings in an RCT in which participants are prospectively recruited on the basis of BP status is required to draw definite conclusions, they added.