ObjeCtiveTo systematically review associations between intake of saturated fat and trans unsaturated fat and all cause mortality, cardiovascular disease (CVD) and associated mortality, coronary heart disease (CHD) and associated mortality, ischemic stroke, and type 2 diabetes. DesignSystematic review and meta-analysis.

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 I2 statistic. 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.

Background: Chronic disease guidelines support tree nut consumption alone or as part of dietary patterns to reduce cardiovascular risk, based on their favorable LDL‐C lowering effect. The effects of nuts on metabolic risk factors other than LDL‐C, however, remain uncertain. Aim: To assess the effect of tree nuts on criteria of the metabolic syndrome, we conducted a systematic review and meta‐analysis of randomized controlled dietary trials. Methods: We searched MEDLINE, EMBASE, CINAHL, and the Cochrane Library (through March 19, 2013). We included relevant randomized controlled trials (RCTs) of 蠅 3 weeks reporting at least 1 criterion of metabolic syndrome. Two 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% confidence intervals (CI). Heterogeneity was assessed by Chi² and quantified by I². Study quality was assessed. Results: Eligibility criteria were met by 39 RCTs including 1,676 participants who were otherwise healthy or had dyslipidemia, metabolic syndrome or diabetes mellitus. Tree nut interventions lowered triglycerides compared with control diet interventions (MD=‐0.07 mmol/L [95%CI, ‐0.11, ‐0.04 mmol/L]), but had no effects on waist circumference, HDL‐C, blood pressure, or fasting blood glucose with the direction of effect favoring tree nuts for all except HDL‐C. Limitations: Most of the trials were of short duration (<12 weeks) and of poor quality (MQS<8). Substantial unexplained heterogeneity remained in most analyses. Conclusions: Pooled analyses show a net benefit of tree nuts for metabolic syndrome with decreases in triglycerides across nut types and no adverse effects on other criteria. Longer and higher quality trials are needed. Protocol registration: Clinicaltrials.gov identifier NCT01630980 Grant Funding Source: Supported by the International Tree Nut Council Nutrition Research & Education Foundation