Omega-3 Fatty Acids, Milk Composition and Human Health
New research is suggesting that the nutritional value of milk depends if cows are fed organic or conventional feedstuffs. One researcher claims that “a switch to organic fruit, vegetables, meat and dairy products would provide significantly higher amounts of dietary antioxidants and omega-3 fatty acids” whereas another concludes the 1.5% increase in our total diet is small and not likely to make a difference. Let’s discuss these findings.
For decades, animal nutritionists have known that milk fat composition is affected by the stage of lactation and the amount and composition of dietary fat. The breed of cow and the proportion of grain versus the diet derived from pasture roughage to silage affect milk composition. What should be our takeaway?
Srednicka-Tober and associates calculated omega-3 fatty acid intakes using α-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and conjugated linoleic acid (CLA). They estimated these to be 58% higher in organic vs conventional milk. By consuming a half-liter of full-fat milk, they estimated omega-3 intake might increase by 39mg. A half-liter is more servings of dairy products than most Americans consume; milk consumption has been declining since 1970.
An increase of 39 mg of omega-3s is helpful but still below the 250-500 mg EPA+DHA recommended daily by many regulatory and expert scientific bodies. Futhermore, the 39 mg is a composite of ALA, CLA, EPA + DHA. Not all omega-3 fatty acids are equivalent. The health benefits of CLA are still unknown. With respect to ALA, studies find less than 1% is converted to DHA within the human body.
For these reasons, it is important to focus on consuming EPA and DHA. The most obvious sources of EPA+DHA are fish and seafood. You can also choose dairy foods/beverages and juices fortified with EPA+DHA. Finally, fish oil and omega-3 dietary supplements are an option with the benefit the EPA+DHA content can be found on the Nutrition Facts label.
Srednicka-Tober D, Baranski M, Seal CJ, Sanderson R, Benbrook C, Steinshamn H, Gromadzka-Ostrowska J, Rembialkowska E, Skwarlo-Sonta K, Eyre M, Cozzi G, Larsen MK, Jordon T, Niggli U, Sakowski T, Calder PC, Burdge GC, Sotiraki S, Stefanakis A, Stergiadis S, Yolcu H, Chatzidimitriou E, Butler G, Stewart G, Leifert C. 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. 2016 Br J Nutr doi: 10.1017/S0007114516000349
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