title: Effect of tree nuts on metabolic syndrome criteria: a systematic review and meta-analysis of randomised controlled trials.
abstract: OBJECTIVE
  To provide a broader evidence summary to inform dietary guidelines of the effect of tree nuts on criteria of the metabolic syndrome (MetS).
  
  
  METHODS
  We conducted a systematic review and meta-analysis of the effect of tree nuts on criteria of the MetS.
  
  
  METHODS
  We searched MEDLINE, EMBASE, CINAHL and the Cochrane Library (through 4 April 2014).
  
  
  METHODS
  We included relevant randomised controlled trials (RCTs) of ≥3 weeks reporting at least one criterion of the MetS.
  
  
  METHODS
  Two 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 I(2) statistic. Study quality and risk of bias were assessed.
  
  
  RESULTS
  Eligibility 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).
  
  
  CONCLUSIONS
  Pooled 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.
  
  
  BACKGROUND
  NCT01630980.
authors: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada.
authors: Sonia
authors: S
authors: Blanco Mejia
authors: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors: Cyril W C
authors: CW
authors: Kendall
authors: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada.
authors: Effie
authors: E
authors: Viguiliouk
authors: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada.
authors: Livia S
authors: LS
authors: Augustin
authors: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada.
authors: Vanessa
authors: V
authors: Ha
authors: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada.
authors: Adrian I
authors: AI
authors: Cozma
authors: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada Faculty of Health Sciences, School of Medicine, Queen's University, Kingston, Ontario, Ontario, Canada.
authors: Arash
authors: A
authors: Mirrahimi
authors: Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada.
authors: Adriana
authors: A
authors: Maroleanu
authors: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada.
authors: Laura
authors: L
authors: Chiavaroli
authors: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada Division of Endocrinology and Metabolism, St. Michael's Hospital, Toronto, Ontario, Canada Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors: Lawrence A
authors: LA
authors: Leiter
authors: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada Department of Clinical Epidemiology & Biostatistics, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada.
authors: Russell J
authors: RJ
authors: de Souza
authors: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada Division of Endocrinology and Metabolism, St. Michael's Hospital, Toronto, Ontario, Canada Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors: David J A
authors: DJ
authors: Jenkins
authors: Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada Division of Endocrinology and Metabolism, St. Michael's Hospital, Toronto, Ontario, Canada Department of Pathology and Molecular Medicine, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada.
authors: John L
authors: JL
authors: Sievenpiper
mesh_terms: D006801:Humans; D050356:Lipid Metabolism / Q000502:physiology*; D008055:Lipids / Q000097:blood*; D024821:Metabolic Syndrome / Q000378:metabolism* / Q000628:therapy; D009754:Nuts; D016032:Randomized Controlled Trials as Topic; D014197:Trees
chemical_list: D008055:Lipids
keywords: Nutrition & Dietetics