title: Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies.
abstract: BACKGROUND
  Beneficial effects of vegetarian and vegan diets on health outcomes have been supposed in previous studies.
  
  
  OBJECTIVE
  Aim of this study was to clarify the association between vegetarian, vegan diets, risk factors for chronic diseases, risk of all-cause mortality, incidence, and mortality from cardio-cerebrovascular diseases, total cancer and specific type of cancer (colorectal, breast, prostate and lung), through meta-analysis.
  
  
  METHODS
  A comprehensive search of Medline, EMBASE, Scopus, The Cochrane Library, and Google Scholar was conducted.
  
  
  RESULTS
  Eighty-six cross-sectional and 10 cohort prospective studies were included. The overall analysis among cross-sectional studies reported significant reduced levels of body mass index, total cholesterol, LDL-cholesterol, and glucose levels in vegetarians and vegans versus omnivores. With regard to prospective cohort studies, the analysis showed a significant reduced risk of incidence and/or mortality from ischemic heart disease (RR 0.75; 95% CI, 0.68 to 0.82) and incidence of total cancer (RR 0.92; 95% CI 0.87 to 0.98) but not of total cardiovascular and cerebrovascular diseases, all-cause mortality and mortality from cancer. No significant association was evidenced when specific types of cancer were analyzed. The analysis conducted among vegans reported significant association with the risk of incidence from total cancer (RR 0.85; 95% CI, 0.75 to 0.95), despite obtained only in a limited number of studies.
  
  
  CONCLUSIONS
  This comprehensive meta-analysis reports a significant protective effect of a vegetarian diet versus the incidence and/or mortality from ischemic heart disease (-25%) and incidence from total cancer (-8%). Vegan diet conferred a significant reduced risk (-15%) of incidence from total cancer.
authors: a Department of Experimental and Clinical Medicine , University of Florence , Florence , Italy.|b Unit of Clinical Nutrition , University Hospital of Careggi , Florence , Italy.
authors: Monica
authors: M
authors: Dinu
authors: a Department of Experimental and Clinical Medicine , University of Florence , Florence , Italy.
authors: Rosanna
authors: R
authors: Abbate
authors: a Department of Experimental and Clinical Medicine , University of Florence , Florence , Italy.|c Don Carlo Gnocchi Foundation Italy , Onlus IRCCS , Florence , Italy.
authors: Gian Franco
authors: GF
authors: Gensini
authors: a Department of Experimental and Clinical Medicine , University of Florence , Florence , Italy.|b Unit of Clinical Nutrition , University Hospital of Careggi , Florence , Italy.
authors: Alessandro
authors: A
authors: Casini
authors: a Department of Experimental and Clinical Medicine , University of Florence , Florence , Italy.|b Unit of Clinical Nutrition , University Hospital of Careggi , Florence , Italy.|c Don Carlo Gnocchi Foundation Italy , Onlus IRCCS , Florence , Italy.
authors: Francesco
authors: http://orcid.org/0000-0001-7113-7424
authors: F
authors: Sofi
mesh_terms: D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000401:mortality*; D003430:Cross-Sectional Studies; D000067269:Diet, Vegan; D014676:Diet, Vegetarian; D006304:Health Status; D006801:Humans; D009369:Neoplasms / Q000453:epidemiology / Q000401:mortality*; D011446:Prospective Studies; D000066988:Vegetarians
keywords: Vegetarian; diet; meta-analysis; vegan