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Am J Clin Nutr. 2015 May;101(5):966-82. doi: 10.3945/ajcn.114.091595. Epub 2015 Mar 25.

The effect of tree nut, peanut, and soy nut consumption on blood pressure: a systematic review and meta-analysis of randomized controlled clinical trials.

Author information

1
From the Isfahan Cardiovascular Research Center (NM and NS), the Hypertension Research Center (NM), Isfahan Cardiovascular Research Institute and the Food Security Research Center (AS-A), Isfahan University of Medical Sciences, Isfahan, Iran; the Nutrition and Food Security Research Center (AS-A) and the Department of Nutrition, Faculty of Health (AS-A), Shahid Sadoughi University of Medical Sciences, Yazd, Iran; the Human Nutrition Unit, Department of Biochemistry and Biotechnology, IISPV, School of Medicine, Rovira i Virgili University, and CIBER Obesity and Nutrition, Reus, Spain (JS-S and MG-F); and Cardiology Division, Department of Medicine, University of British Columbia, Vancouver, Canada (KH).

Abstract

BACKGROUND:

Although several studies have assessed the effects of nut consumption (tree nuts, peanuts, and soy nuts) on blood pressure (BP), the results are conflicting.

OBJECTIVE:

The aim was to conduct a systematic review and meta-analysis of published randomized controlled trials (RCTs) to estimate the effect of nut consumption on BP.

DESIGN:

The databases MEDLINE, SCOPUS, ISI Web of Science, and Google Scholar were searched for RCTs carried out between 1958 and October 2013 that reported the effect of consuming single or mixed nuts (including walnuts, almonds, pistachios, cashews, hazelnuts, macadamia nuts, pecans, peanuts, and soy nuts) on systolic BP (SBP) or diastolic BP (DBP) as primary or secondary outcomes in adult populations aged ≥18 y. Relevant articles were identified by screening the abstracts and titles and the full text. Studies that evaluated the effects for <2 wk or in which the control group ingested different healthy oils were excluded. Mean ± SD changes in SBP and DBP in each treatment group were recorded for meta-analysis.

RESULTS:

Twenty-one RCTs met the inclusion criteria. Our findings suggest that nut consumption leads to a significant reduction in SBP in participants without type 2 diabetes [mean difference (MD): -1.29; 95% CI: -2.35, -0.22; P = 0.02] but not in the total population. Subgroup analyses of different nut types suggest that pistachios, but not other nuts, significantly reduce SBP (MD: -1.82; 95% CI: -2.97, -0.67; P = 0.002). Our study suggests that pistachios (MD: -0.80; 95% CI: -1.43, -0.17; P = 0.01) and mixed nuts (MD: -1.19; 95% CI: -2.35, -0.03; P = 0.04) have a significant reducing effect on DBP. We found no significant changes in DBP after the consumption of other nuts.

CONCLUSIONS:

Total nut consumption lowered SBP in participants without type 2 diabetes. Pistachios seemed to have the strongest effect on reducing SBP and DBP. Mixed nuts also reduced DBP.

KEYWORDS:

almond; blood pressure; cashew; nut; pistachio; randomized controlled trials; walnut

PMID:
25809855
DOI:
10.3945/ajcn.114.091595
[Indexed for MEDLINE]

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