Higher PUFA and n-3 PUFA, conjugated linoleic acid, α-tocopherol and iron, but lower iodine and selenium concentrations in organic milk: a systematic literature review and meta- and redundancy analyses.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis (graded by design analogy, not clinical CEBM)
PubMed 26878105 · doi:10.1017/S0007114516000349
What was done
The authors conducted a systematic literature review and meta-analyses synthesizing data from 170 published studies comparing the nutrient composition of organic and conventional bovine milk. Redundancy analysis of data from a large cross-European milk quality survey was also conducted to identify drivers of compositional differences.
What was found
No significant differences were found in total SFA and MUFA concentrations. Organic milk had higher concentrations of total PUFA (by 7%, 95% CI -1 to 15%), n-3 PUFA (by 56%, 95% CI 38 to 74%), α-linolenic acid (by 69%, 95% CI 53 to 84%), EPA+DPA+DHA (by 57%, 95% CI 27 to 87%), and conjugated linoleic acid (by 41%, 95% CI 14 to 68%). Total n-6 PUFA and linoleic acid (LA) concentrations did not differ significantly, while n-6:n-3 and LA:ALA ratios were lower in organic milk by 71% (95% CI -122 to -20%) and 93% (95% CI -116 to -70%), respectively. Organic milk also had significantly higher α-tocopherol and Fe, but lower I and Se concentrations (specific numbers not reported in the abstract). Higher grazing and conserved forage intakes in organic systems were identified as the main driver of these differences.
Why it matters
This synthesis clarifies that organic dairy management practices systematically alter milk lipid and mineral profiles, increasing desirable n-3 fatty acids while reducing iodine and selenium levels.
Limits
The abstract omits exact numerical values and effect sizes for α-tocopherol, iron, iodine, and selenium. It evaluates chemical composition rather than clinical or human health outcomes.
Cited by
- supports All dietary animal sources of fat contain some amount of linoleic acid.