Researchers know that grass and legume forage promotes cow health and improves the fatty acid profile in organic dairy products, but until now they hadn’t measured the difference.
In the first large-scale, nationwide comparison of organic and conventional milk, scientists found that organic has a much more healthful ratio of omega-6 fatty acids to omega-3 fatty acids.
Led by a Washington State University researcher, scientists published their findings Dec. 9 in the online journal of the Public Library of Science, a nonprofit publisher and advocacy organization.
“We were surprised by the magnitude of the nutritional quality differences we documented in this study,” lead author Charles Benbrook wrote.
The 18-month study analyzed nearly 400 samples of milk from seven regions around the U.S. The organic milk came from cows managed by farmer-owners of the Cooperative Regions of Organic Producer Pools, which markets milk through the Organic Valley brand.
The two organizations helped fund the study but had no role in its design or analysis, which was funded through the Measure to Manage program in WSU’s Center for Sustaining Agriculture and Natural Resources, Benbrook said.
The nutritional analysis focused on the milk’s fatty acids. Consumption of more omega-6 fatty acids than omega-3 fatty acids is considered a risk factor for health problems such as cardiovascular disease, cancer, excessive inflammation and autoimmune diseases. The higher the ratio of omega-6 to omega-3, the greater the associated health risk.
Western diets typically have a ratio of about 10-to-1 to 15-to-1, while a ratio of 2.3-to-1 is thought to maximize heart health.
Testing looked at whole milk, because recent studies contradict the assumption that low-fat milk is more healthful. To the contrary, increased dairy fat consumption has been linked to diminished weight gain, reduced waist circumference and reduced risk of cardiovascular disease and colorectal cancer.
Researchers measured conventional milk’s average omega-6 to omega-3 fatty acid ratio at 5.8, more than twice that of organic milk’s ratio of 2.3. They credited the more healthful organic milk ratio to the greater reliance on pasture and forage-based feeds required by the National Organic Program.
Even under conventional management, milk samples from Humboldt County, Calif., where both types of dairies graze their cattle for more than 250 days a year, were similar to organic in fatty acids.
The researchers found that fatty acid ratios in the human diet could be lowered by almost 40 percent by switching from three daily servings of conventional dairy products to 4.5 daily servings of mostly full-fat organic dairy products. Avoiding a few foods each day that are high in omega-6 fatty acids lowered the ratio another 40 percent.
The team also compared the fatty acids in dairy products with those in fish.
“We were surprised to find that recommended intakes of full-fat milk products supply far more of the major omega-3 fatty acid, ALA (alpha-linolenic acid), than recommended servings of fish,” Donald Davis, co-author and WSU research associate, said. Conventional milk had about nine times more ALA than fish; organic milk had 14 times more.