Objective The antihypertensive effect of fish oil was estimated from randomized trials using metaregression analysis. Modification of the blood pressure (BP) effect by age, gender, blood pressure, and body mass index was examined.Methods A total of 90 randomized trials of fish oil and BP were identi

Blood pressure response to fish oil supplementation: metaregression analysis of randomized trials.

BACKGROUND In a meta-analysis of 31 placebo-controlled trials on 1356 subjects, we examined the effect of omega-3 fatty acids in fish oil on blood pressure by grouping studies that were similar in fish oil dose, length of treatment, health of the subjects, or study design. METHODS AND RESULTS The mean reduction in blood pressure caused by fish oil for the 31 studies was -3.0/-1.5 mm Hg (95% confidence intervals: systolic blood pressure: -4.5, -1.5; diastolic blood pressure: -2.2, -0.8). There was a statistically significant dose-response effect when studies were grouped by omega-3 fatty acid dose: -1.3/-0.7 mm Hg at doses < or = 3 g/d, -2.9/-1.6 mm Hg at 3.3 to 7 g/d, and -8.1/-5.8 mm Hg at 15 g/d. Both eicosapentaenoic acid and docosahexaenoic acid were significantly related to blood pressure response. There was no effect on blood pressure in eight studies of "healthy" persons (mean reduction, -0.4/-0.7 mm Hg) at an overall mean dose of 4.2 g omega-3 fatty acids/d. By contrast, there was a significant effect of -3.4/-2.0 mm Hg in the group of hypertensive studies with a mean fish oil dose of 5.6 g/d and on systolic blood pressure only in six studies of hypercholesterolemic patients (-4.4/-1.1 mm Hg) with a mean dose of 4.0 g/d. A nonsignificant decrease in blood pressure was observed in four studies of patients with atherosclerotic cardiovascular disease (-6.3/-2.9 mm Hg). Variations in the length of treatment (from 3 to 24 weeks), type of placebo, and study design (crossover or parallel groups) did not appear to account for inconsistent findings among studies. CONCLUSIONS There is a dose-response effect of fish oil on blood pressure of -0.66/-0.35 mm Hg/g omega-3 fatty acids. The hypotensive effect may be strongest in hypertensive subjects and those with clinical atherosclerotic disease or hypercholesterolemia.

Does fish oil lower blood pressure? A meta-analysis of controlled trials.

Background: Several lines of evidence suggest that supplementation of diet with omega-3 polyunsaturated fatty acids (ω-3) PUFA), commonly referred to as fish oils, may reduce blood pressure (BP). However, most clinical trials of ω-3 PUFA supplementation have been of insufficient size to detect relevant BP changes. Methods: We conducted a meta-analysis of 17 controlled clinical trials of ω-3 PUFA supplementation. To estimate an overall effect of ω-3 PUFA supplementation on BP, we calculated the net BP change in each trial (BP A in ω-3 PUFA group minus BP A in control group), which was then weighted according to the inverse of the variance. Results: In the 11 trials that enrolled normotensive individuals (n=728), ω-3 PUFA supplementation led to significant reductions of systolic BP (SBP) and diastolic BP (DBP) in two and one trials, respectively. In the six studies that enrolled untreated hypertensives (n=291), significant reductions of SBP and DBP were present in two and four trials, respectively. Weighted, pooled estimates of SBP and DBP change (mm Hg) with 95% confidence intervals were —1.0 (—2.0 to 0.0) and —0.5 (—1.2 to +0.2) in the trials of normotensives, and —5.5 (—8.1 to —2.9) and —3.5 (—5.0 to —2.1) in the trials of untreated hypertensives. In 13 of 17 studies, trial duration was less than 3 months. Doses of ω-3 PUFA tended to be high (average dose >3 g/d in 11 trials). The magnitude of BP reduction was greatest at high BP but was not significantly associated with dose of ω-3 PUFA. Side effects, most commonly eructation and a fishy taste, occurred more frequently in ω-3 PUFA participants than in control participants (28% vs 13%,P Conclusions: Our analyses indicate that diet supplementation with a relatively high dose of ω-3 PUFA, generally more than 3 g/d, can lead to clinically relevant BP reductions in individuals with untreated hypertension. However, use of ω-3 PUFA as antihypertensive therapy will require demonstration of long-term efficacy and patient acceptability of lower doses. (Arch Intern Med. 1993;153:1429-1438)

Does Supplementation of Diet With 'Fish Oil' Reduce Blood Pressure?: A Meta-analysis of Controlled Clinical Trials

Lipoproteins, nutrition, and heart disease

Studies of whether polyunsaturated fatty acids in fish oil--in particular, eicosapentaenoic and docosahexaenoic acids--lower blood pressure have varied in design and results. We conducted a population-based, randomized, 10-week dietary-supplementation trial in which the effects of 6 g per day of 85 percent eicosapentaenoic and docosahexaenoic acids were compared with those of 6 g per day of corn oil in 156 men and women with previously untreated stable, mild essential hypertension. The mean systolic blood pressure fell by 4.6 mm Hg (P = 0.002), and diastolic pressure by 3.0 mm Hg (P = 0.0002) in the group receiving fish oil; there was no significant change in the group receiving corn oil. The differences between the groups remained significant for both systolic (6.4 mm Hg; P = 0.0025) and diastolic (2.8 mm Hg; P = 0.029) pressure after control for anthropometric, lifestyle, and dietary variables. The decreases in blood pressure were larger as concentrations of plasma phospholipid n-3 fatty acids increased (P = 0.027). Dietary supplementation with fish oil did not change mean blood pressure in the subjects who ate fish three or more times a week as part of their usual diet, or in those who had a base-line concentration of plasma phospholipid n-3 fatty acids above 175.1 mg per liter. We conclude that eicosapentaenoic and docosahexaenoic acids reduce blood pressure in essential hypertension, depending on increases in plasma phospholipid n-3 fatty acids.

https://www.nejm.org/doi/pdf/10.1056/NEJM199003223221202

Effect of eicosapentaenoic and docosahexaenoic acids on blood pressure in hypertension. A population-based intervention trial from the Tromsø study.

pressures related to situation and the influence of other drug users. In the outpatient group the most risky times appeared to be at the beginning and end of the withdrawal schedule. Six subjects (21% ofthis group) failed in the first 14 days of the eight week programme, and 9 (31%) failed in the last week. Ofthe six inpatients who failed, two did so on the first day and the four others in the last six days. The outpatient sample was more likely to remain in contact with the hospital's drug dependence services (x2=9 19, p<OO5); 16 out of 29 (55%)received further counselling or treatment from the clinic after their attempt at withdrawal whereas 22 out of 37 (71%) of the inpatients lost contact with the clinic. A further analysis of the data for all subjects showed that those addicts who had been successfully withdrawn from drugs were less likely to remain in immediate contact with the clinic and took longer to re-establish contact (t=2-38, p<O05).

https://www.bmj.com/content/bmj/293/6539/104.full.pdf

C. J. H. Jones

Papers

Effect of dietary supplementation with fish oil on systolic blood pressure in mild essential hypertension.