Crystal Smith-Spangler, MD, MS; Margaret L. Brandeau, PhD; Grace E. Hunter, BA; J. Clay Bavinger, BA; Maren Pearson, BS; Paul J. Eschbach; Vandana Sundaram, MPH; Hau Liu, MD, MS, MBA, MPH; Patricia Schirmer, MD; Christopher Stave, MLS; Ingram Olkin, PhD; Dena M. Bravata, MD, MS
Note: As the corresponding author and guarantor of the manuscript, Crystal Smith-Spangler, MD, MS, takes full responsibility for the work as a whole, including the study design, access to data, and decision to submit the manuscript for publication.
Acknowledgment: The authors thank the staff of DocXpress at Lane Medical Library for document retrieval.
Financial Support: Ms. Pearson was supported by a Stanford Undergraduate Research Grant.
Potential Conflicts of Interest: None disclosed. Forms can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M12-0192.
Requests for Single Reprints: Crystal Smith-Spangler, MD, MS, Stanford Center for Health Policy and Center for Primary Care and Outcomes Research, 117 Encina Commons, Stanford University, Stanford, CA 94305-6019; e-mail, email@example.com.
Current Author Addresses: Dr. Smith-Spangler: Division of General Medical Disciplines, Stanford University, 1265 Welch Road, Medical School Office Building, MC 5411, Stanford, CA 94305.
Dr. Brandeau: Department of Management Science and Engineering, Huang Engineering Center, Room 262, Stanford University, Stanford, CA 94205-4026.
Ms. Hunter, Mr. Bavinger, Ms. Pearson, Mr. Eschbach, Ms. Sundaram, and Drs. Liu and Bravata: Center for Health Policy, Stanford University, 117 Encina Commons, Stanford, CA 94305-6019.
Dr. Schirmer: Veterans Affairs Palo Alto Health Care System, 3801 Miranda Avenue (132), Palo Alto, CA 94304.
Mr. Stave: Lane Medical Library, 300 Pasteur Drive, L-109, Stanford, CA 94305-5123.
Dr. Olkin: Department of Statistics, Sequoia Hall, 390 Serra Mall, Stanford University, Stanford, CA 94305-4065.
Author Contributions: Conception and design: C. Smith-Spangler, J.C. Bavinger, M. Pearson, V. Sundaram, D.M. Bravata, I. Olkin.
Analysis and interpretation of the data: C. Smith-Spangler, M.L. Brandeau, G.E. Hunter, J.C. Bavinger, M. Pearson, P.J. Eschbach, V. Sundaram, P. Schirmer, D.M. Bravata, I. Olkin.
Drafting of the article: C. Smith-Spangler, M.L. Brandeau, J.C. Bavinger, V. Sundaram, P. Schirmer, D.M. Bravata.
Critical revision of the article for important intellectual content: C. Smith-Spangler, M.L. Brandeau, V. Sundaram, H. Liu, D.M. Bravata, I. Olkin.
Final approval of the article: C. Smith-Spangler, M.L. Brandeau, J.C. Bavinger, P.J. Eschbach, V. Sundaram, H. Liu, P. Schirmer, D.M. Bravata, I. Olkin.
Provision of study materials or patients: C. Smith-Spangler, D.M. Bravata.
Statistical expertise: C. Smith-Spangler, D.M. Bravata, I. Olkin.
Administrative, technical, or logistic support: G.E. Hunter, M. Pearson, C. Stave.
Collection and assembly of data: C. Smith-Spangler, M.L. Brandeau, G.E. Hunter, J.C. Bavinger, M. Pearson, P.J. Eschbach, V. Sundaram, H. Liu, P. Schirmer, C. Stave, D.M. Bravata.
This article has been corrected. The original version (PDF) is appended to this article as a supplement.
The health benefits of organic foods are unclear.
To review evidence comparing the health effects of organic and conventional foods.
MEDLINE (January 1966 to May 2011), EMBASE, CAB Direct, Agricola, TOXNET, Cochrane Library (January 1966 to May 2009), and bibliographies of retrieved articles.
English-language reports of comparisons of organically and conventionally grown food or of populations consuming these foods.
2 independent investigators extracted data on methods, health outcomes, and nutrient and contaminant levels.
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%]).
Studies were heterogeneous and limited in number, and publication bias may be present.
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.
Crystal Smith-Spangler, Margaret L. Brandeau, Grace E. Hunter, J. Clay Bavinger, Maren Pearson, Paul J. Eschbach, et al. Are Organic Foods Safer or Healthier Than Conventional Alternatives?: A Systematic Review. Ann Intern Med. 2012;157:348–366. doi: 10.7326/0003-4819-157-5-201209040-00007
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Published: Ann Intern Med. 2012;157(5):348-366.
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