A Washington State University-led team studied about 400 samples of whole milk, both traditionally produced and organic, and found a key difference in the balance of fatty acids. Organic milk seems to have a much higher proportion of omega-3s compared with omega-6s.

The difference could benefit two important groups: developing babies and children, and people concerned about heart disease.

Whether organic milk is really better for you has been a controversial question, and many medical societies say there’s no evidence to support it.

“We think that this study will definitely lead them to reconsider,” said WSU research professor Chuck Benbrook, who led the new study. “There is, in fact, a lot of evidence that this omega-6 to omega-3 fatty acid ratio is actually very important for pregnant women and children.”

The researchers attribute the difference to organically-raised cattle eating more grass and forage instead of processed grain feed.

Benbrook says most Americans consume 10 to 15 times more omega-6 fatty acids than omega-3s. Many experts say that ratio should be down closer to 2-to-1, though there is some disagreement on how important the ratio is.

Clinical dietician Judy Simon of University of Washington Medicine said the study adds to the evidence that organic dairy, like organic meat, can help improve people’s fatty acid mix.

“I'm not surprised with the results, because we’ve found with the organic beef that’s like totally grass-fed, we’re seeing a difference in the fatty acid profile. So we think it does make a difference what we feed our animals,” said Simon.

She added that the issue must be studied more, and that scientific and medical societies are rightly conservative about rewriting their pronouncements on questions such as the health benefits of organics.

The WSU study was funded largely by players in the organic foods industry and is published in PLoS ONE.