Effect of tree nuts on metabolic syndrome criteria: a systematic review and meta-analysis of randomised controlled trials Journal Articles uri icon

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abstract

  • ObjectiveTo provide a broader evidence summary to inform dietary guidelines of the effect of tree nuts on criteria of the metabolic syndrome (MetS).DesignWe conducted a systematic review and meta-analysis of the effect of tree nuts on criteria of the MetS.Data sourcesWe searched MEDLINE, EMBASE, CINAHL and the Cochrane Library (through 4 April 2014).Eligibility criteria for selecting studiesWe included relevant randomised controlled trials (RCTs) of ≥3 weeks reporting at least one criterion of the MetS.Data extractionTwo or more independent reviewers extracted all relevant data. Data were pooled using the generic inverse variance method using random effects models and expressed as mean differences (MD) with 95% CIs. Heterogeneity was assessed by the Cochran Q statistic and quantified by the I2statistic. Study quality and risk of bias were assessed.ResultsEligibility criteria were met by 49 RCTs including 2226 participants who were otherwise healthy or had dyslipidaemia, MetS or type 2 diabetes mellitus. Tree nut interventions lowered triglycerides (MD=−0.06 mmol/L (95% CI −0.09 to −0.03 mmol/L)) and fasting blood glucose (MD=−0.08 mmol/L (95% CI −0.16 to −0.01 mmol/L)) compared with control diet interventions. There was no effect on waist circumference, high-density lipoprotein cholesterol or blood pressure with the direction of effect favouring tree nuts for waist circumference. There was evidence of significant unexplained heterogeneity in all analyses (p<0.05).ConclusionsPooled analyses show a MetS benefit of tree nuts through modest decreases in triglycerides and fasting blood glucose with no adverse effects on other criteria across nut types. As our conclusions are limited by the short duration and poor quality of the majority of trials, as well as significant unexplained between-study heterogeneity, there remains a need for larger, longer, high-quality trials.Trial registration numberNCT01630980.

authors

  • Blanco Mejia, Sonia
  • Kendall, Cyril WC
  • Viguiliouk, Effie
  • Augustin, Livia S
  • Ha, Vanessa
  • Cozma, Adrian I
  • Mirrahimi, Arash
  • Maroleanu, Adriana
  • Chiavaroli, Laura
  • Leiter, Lawrence A
  • de Souza, Russell
  • Jenkins, David JA
  • Sievenpiper, John L

publication date

  • July 2014