Effects of Different Dietary Interventions on Blood Pressure
Systematic Review and Meta-Analysis of Randomized Controlled Trials

Gay HC, Rao SG, Vaccarino V, et al.
Hypertension. 2016;67:733-739

Background

Current clinical guidelines recommend lifestyle changes for the management of hypertension, based on the results of clinical trials, systematic reviews and meta-analyses [1,2].
Even relatively small reductions in BP can dramatically reduce the incidence of CV disease and mortality. In every-day clinical practice, recommendation of a specific dietary approach may be challenging, since the relative benefit from these non-pharmacological interventions is not well established.
In this systematic review and meta-analysis of 24 randomised controlled trials with 23858 participants, the aggregate BP effects associated with dietary interventions were quantified, and the relative BP changes observed between specific dietary patterns were compared.

Main results

• The overall pooled net effect of dietary intervention was SBP: −3.07 mm Hg; 95% CI: −3.85 to −2.30 and DBP: −1.81 mm Hg; 95% CI: −2.24 to −1.38
• The Dietary Approaches to Stop Hypertension (DASH) diet had the largest net effect (SBP: −7.62 mm Hg; 95% CI: −9.95 to −5.29, DBP: −4.22 mm Hg; 95% CI: −5.87 to −2.57)
• Mediterranean diets led to a significant incremental reduction in diastolic, but not systolic BP (SBP: −1.17 mm Hg; 95% CI: −2.81 to 0.46 and DBP: −1.44 mm Hg; 95% CI: −2.11 to −0.76).
• Low-sodium diets led to a pooled net decrease of SBP: −2.06 mm Hg; 95% CI: −3.50 to −0.63 and DBP: −1.30 mm Hg; 95% CI: −2.37 to −0.23.
• Low-calorie diets led to a pooled net decrease of SBP: −3.18 mm Hg; 95% CI: −4.24 to −2.11 and DBP: −1.28 mm Hg; 95% CI: −1.87 to −0.69.
• For every additional 1 kg of weight loss, there was an associated additional reduction in SBP of -0.36 mm Hg and in DBP of -0.13 mm Hg
• Combined low-sodium/high-potassium diets led to a pooled net decrease of SBP: −3.14 mm Hg; 95% CI: −6.27 to −0.02 and DBP: −2.01 mm Hg; 95% CI: −3.40 to −0.62
• Combined low-sodium/low-calorie diets led to a pooled net decrease of SBP: −2.38 mm Hg; 95% CI: −3.79 to −0.98 and DBP: −1.33 mm Hg; 95% CI: −2.04 to −0.62
• Individuals with DM and individuals with baseline BMI >35 did not experience statistically significant incremental BP reductions
• Normotensives, individuals already receiving pharmacological therapies, groups with follow-up > 24 months, participants of larger trials (n > 100), and participants of trials with BP reduction as the primary outcome, experienced a significantly smaller effect

Conclusion

This large meta-analysis shows that dietary interventions lead to clinically significant net BP reductions. Important variations in effectiveness were observed between subgroups and certain dietary approaches are better targeted to individuals with specific characteristics. The DASH intervention may be the most appropriate initial recommendation when BP control is the principle objective.

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References

1. Miller ER III, Erlinger TP, Young DR, et al. Results of the Diet, Exercise, and Weight Loss Intervention Trial (DEW-IT). Hypertension. 2002;40:612–618
2. Appel LJ, Moore TJ, Obarzanek E, et al. A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. N Engl J Med. 1997;336:1117–1124