Are organic foods safer or healthier than conventional alternatives?: a systematic review.
Level 1 - systematic review of randomized trials
Systematic review of human studies and nutrient/contaminant comparative studies
PubMed 22944875 · doi:10.7326/0003-4819-157-5-201209040-00007
What was done
Investigators conducted a systematic review searching MEDLINE (1966 to May 2011), EMBASE, CAB Direct, Agricola, TOXNET, the Cochrane Library (1966 to May 2009), and bibliographies. They included English-language studies comparing organic and conventional foods or populations consuming them. Two independent investigators extracted data on study methods, health outcomes, and nutrient and contaminant levels.
What was found
The review analyzed 17 human studies and 223 food studies. Only 3 human studies evaluated clinical outcomes, finding no significant differences between organic and conventional diets for allergic outcomes (eczema, wheeze, atopic sensitization) or symptomatic Campylobacter infection. Two studies found lower urinary pesticide levels in children consuming organic diets, while adult biomarker and nutrient measures showed no clinically meaningful differences. Food nutrient differences were highly heterogeneous except for higher phosphorus in conventional produce, which was not clinically significant. Detectable pesticide residue risk was lower in organic produce (risk difference -30%, 95% CI -37% to -23%), though differences in exceeding maximum allowed limits were small. Escherichia coli contamination risk did not differ by farming method, and overall bacterial contamination in chicken and pork was unrelated to farming type. However, risk for isolating bacteria resistant to 3 or more antibiotics was higher in conventional chicken and pork (risk difference 33%, 95% CI 21% to 45%).
Why it matters
The findings show that organic foods lack strong evidence of nutritional superiority or clinical health advantages compared to conventional foods. However, organic choices reduce exposure to detectable pesticide residues and antibiotic-resistant bacteria in meat.
Limits
Only 3 human studies examined clinical health outcomes, and total human trials were few (n = 17). Food nutrient and contaminant analyses had high heterogeneity, the search was limited to English-language publications, and publication bias may be present.
Cited by
- partial Organic food provides higher nutritional value and lowers exposure to pesticides, fertilizer chemicals, and genetically modified ingredients.