title: Are organic foods safer or healthier than conventional alternatives?: a systematic review.
abstract: BACKGROUND
  The health benefits of organic foods are unclear.
  
  
  OBJECTIVE
  To review evidence comparing the health effects of organic and conventional foods.
  
  
  METHODS
  MEDLINE (January 1966 to May 2011), EMBASE, CAB Direct, Agricola, TOXNET, Cochrane Library (January 1966 to May 2009), and bibliographies of retrieved articles.
  
  
  METHODS
  English-language reports of comparisons of organically and conventionally grown food or of populations consuming these foods.
  
  
  METHODS
  2 independent investigators extracted data on methods, health outcomes, and nutrient and contaminant levels.
  
  
  RESULTS
  17 studies in humans and 223 studies of nutrient and contaminant levels in foods met inclusion criteria. Only 3 of the human studies examined clinical outcomes, finding no significant differences between populations by food type for allergic outcomes (eczema, wheeze, atopic sensitization) or symptomatic Campylobacter infection. Two studies reported significantly lower urinary pesticide levels among children consuming organic versus conventional diets, but studies of biomarker and nutrient levels in serum, urine, breast milk, and semen in adults did not identify clinically meaningful differences. All estimates of differences in nutrient and contaminant levels in foods were highly heterogeneous except for the estimate for phosphorus; phosphorus levels were significantly higher than in conventional produce, although this difference is not clinically significant. The risk for contamination with detectable pesticide residues was lower among organic than conventional produce (risk difference, 30% [CI, -37% to -23%]), but differences in risk for exceeding maximum allowed limits were small. Escherichia coli contamination risk did not differ between organic and conventional produce. Bacterial contamination of retail chicken and pork was common but unrelated to farming method. However, the risk for isolating bacteria resistant to 3 or more antibiotics was higher in conventional than in organic chicken and pork (risk difference, 33% [CI, 21% to 45%]).
  
  
  CONCLUSIONS
  Studies were heterogeneous and limited in number, and publication bias may be present.
  
  
  CONCLUSIONS
  The published literature lacks strong evidence that organic foods are significantly more nutritious than conventional foods. Consumption of organic foods may reduce exposure to pesticide residues and antibiotic-resistant bacteria.
  
  
  BACKGROUND
  None.
authors.affiliation: Stanford Center for Health Policy and Center for Primary Care and Outcomes Research, 117 Encina Commons, Stanford University, Stanford, CA 94305-6019, USA. csmithsp@stanford.edu
authors.forename: Crystal
authors.initials: C
authors.lastname: Smith-Spangler
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Brandeau
authors.forename: Grace E
authors.initials: GE
authors.lastname: Hunter
authors.forename: J Clay
authors.initials: JC
authors.lastname: Bavinger
authors.forename: Maren
authors.initials: M
authors.lastname: Pearson
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Eschbach
authors.forename: Vandana
authors.initials: V
authors.lastname: Sundaram
authors.forename: Hau
authors.initials: H
authors.lastname: Liu
authors.forename: Patricia
authors.initials: P
authors.lastname: Schirmer
authors.forename: Christopher
authors.initials: C
authors.lastname: Stave
authors.forename: Ingram
authors.initials: I
authors.lastname: Olkin
authors.forename: Dena M
authors.initials: DM
authors.lastname: Bravata
mesh_terms: D024881:Drug Resistance, Bacterial; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D058870:Food, Organic / Q000032:analysis / Q000382:microbiology; D006801:Humans; D009753:Nutritive Value; D010573:Pesticide Residues / Q000032:analysis; D014815:Vitamins / Q000032:analysis
chemical_list: D010573:Pesticide Residues; D014815:Vitamins