Higher PUFA and n-3 PUFA, conjugated linoleic acid, α-tocopherol and iron, but lower iodine and selenium in organic milk: a systematic literature review and meta- and redundancy analyses

Summary

This systematic review and meta-analysis synthesised the available peer-reviewed literature comparing the nutritional composition of organic and conventional milk. Using redundancy analysis to account for intercorrelation among nutrients, the authors found robust evidence that organic milk contains higher concentrations of several nutritionally beneficial fatty acids and antioxidants, likely attributable to greater reliance on pasture-based feeding in organic systems. However, the review also identified trade-offs, with organic milk showing lower concentrations of iodine and selenium — micronutrients of public health significance in populations reliant on dairy as a dietary source.

Regional applicability

The findings are directly applicable to the UK context, where iodine intake is a recognised public health concern and dairy is a primary dietary source; the trade-off between elevated n-3 PUFA and CLA on one hand and reduced iodine and selenium on the other is particularly pertinent for UK consumers and dietetic guidance on organic dairy consumption.

Key measures

PUFA concentration (% fatty acids); n-3 PUFA concentration; conjugated linoleic acid (CLA) concentration; α-tocopherol (mg/kg); iron (mg/kg); iodine (µg/kg); selenium (µg/kg)

Outcomes reported

The study compared concentrations of fatty acids, fat-soluble vitamins, minerals and other nutritionally relevant compounds in organic versus conventional milk. It reported significantly higher levels of PUFA, n-3 PUFA, conjugated linoleic acid, α-tocopherol and iron in organic milk, alongside lower levels of iodine and selenium.

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