The organic milk study

Responsible marketers have emphasized for years that the organic in organic food is about a production system that avoids synthetic pesticides and other farm inputs and not necessarily about the healthfulness of the food itself. A study of organic milk reported in the online science journal PLOS ONE indicates that, at least in the case of milk, organic farm practices may lead to healthier products.

The study, from a team led by scientists at the Center for Sustaining Agriculture and Natural Resources of Washington State University, found that, averaged over 12 months, organic milk contained 25% less ω-6 fatty acids and 62% more ω-3 fatty acids than conventional milk. Without getting into the health aspects, the scientists report that  average ω-6/ω-3 intake ratios in the human diet have been increasing, thereby increasing probable risk factors for a wide range of developmental and chronic health problems.

The study indicates that the difference may come not so much from the organic feed program but from the fact that milk from cows consuming significant amounts of grass and legume-based forages contains higher concentrations of ω-3 fatty acids and conjugated linoleic acid than milk from cows lacking routine access to pasture and fed substantial quantities of grains, especially corn. The US National Organic Program requires that lactating cows on certified organic farms receive at least 30% of daily dry matter intake from pasture during that portion of the year when pasture grasses and legumes are actively growing, with a minimum of 120 days per year. There is no similar requirement for conventional milk cows.

The study concludes that full-fat organic dairy products offer clear advantages for individuals striving to reduce their overall dietary ω-6/ω-3 ratio.

No doubt there will be push-back from the conventional dairy industry, particularly to the authors suggestion that the problem of too much ω-6 fatty acids in conventional milk arises because the proportion of fresh forage in conventional dairy diets has decreased continuously over the last 40 years in the U.S. and that grain-based “total mixed rations” now dominate the conventional U.S. dairy sector. These “total mixed rations” may include such ingredients as byproducts from vegetable oil, soy biodiesel, or ethanol plants, brewers dried grain from malting barley, or a wide range of food processing wastes.

This is one study that does not state that more research is needed. The authors appear to be of the opinion that high ω-6 fatty acid levels are clearly associated with non-pasture sources of nutrition for dairy cattle and that expected benefits from reduced dietary ω-6/ω-3 ratios, coupled with increased long-chain ω-3 intakes, are almost certainly greatest for women hoping to bear a child, for pregnant women and their babies, and for infants and children through adolescence. They state that high ω-6/ω-3 ratios and/or low long-chain ω-3 intakes predispose the developing fetus to a wide range of adverse neurological and immune system disorders, and can also impair the visual system.

An abstract and the full study are available at http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0082429

This GallonDaily article has been amended to remove our mistake with respect to the role of conjugated linoleic acid (CLA). Our apologies. The authors of the original article consider CLA in milk to be a positive for human health and find more CLA in milk from pasture-fed cows than in conventional milk.

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