Marion Nestle, a professor of nutrition and public health at New York University, said the results came as no surprise.
"One aspect of organic production methods is that cows must be allowed to graze on grass. The omega ratios reflect grass feeding. The study is further evidence that the organic rules are doing what they are supposed to be doing," said Nestle, who wasn't involved in the new study.
The researchers also found seasonal differences in organic milk's fatty acid composition. Organic milk produced in spring and summer had higher levels of conjugated linoleic acid (CLA), an important group of fatty acids.
"CLA levels go up sharply beginning in May and tail off as the summer progresses, reaching lower baseline level for the winter," Benbrook said, adding that CLA levels mirror the amount of fresh forage in the cows' diet.
The team also compared the fatty acids in dairy products to those in fish, and found that recommended intakes of full-fat milk products supply more of the major omega-3 fatty acid, ALA, than do recommended servings of fish.
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