Cows that feed on pasture grasses and dry forage produce milk with more beneficial fatty acids than cows that eat supplemental grains like corn and soybeans, according to a study released Dec. 9.
Funded by Organic Valley and conducted by scientists at Washington State University, the first large-scale, nationwide comparison of organic and conventional milk found that organic whole milk is 62 percent higher in heart-healthy omega-3 fatty acid than conventional whole milk.
Scientists tested 384 samples of organic and conventional milk in 14 dairy plants in seven regions over a period of
18 months. Only organic milk from Organic Valley farms was tested for comparison.
“We’re just thrilled to have a study that shows a direct relationship between (organic) farming practices and healthier milk,” said George Siemon, Organic Valley CEO. “This confirms what we already knew.”
In order to be legally considered organic, dairy cows must graze during the growing season on pasture grasses, which are rich in omega-3s. Cows on conventional dairy farms typically eat more corn, which is high in omega-6s. Organic whole milk has a more favorable balance of the two fatty acids, the study found.
“As much as we feel that this study shows the benefit of organic agriculture, this really is about the higher forage diet and pasturing,” Siemon said, emphasizing that pasture grazing would improve the fatty acid content in nonorganic milk as well.
While both fatty acids provide essential health benefits, the typical Western diet includes a higher level of omega-6s, which come from processed plant oils. Western diets typically have an omega-6 to omega-3 ratio of about 10-to-1 to 15-to-1, while a ratio of 2.3-to-1 is thought to maximize heart health, according to the study.
Although the role of milk in a healthy diet is debated by some experts, it is “probably the best, most readily available source of calcium, protein, vitamin D and potassium available,” said Marisa Pruitt, a registered dietitian nutritionist at Gundersen Health System.
“That makes milk a unique and valuable package,” she said.
Pruitt cautioned that whole milk is still high in calories and emphasized that the best nutrient to calorie ratio comes from low-fat milk. Fat-free milk, however, is stripped of the beneficial nutrients found in the milk fat.
Omega-3 fatty acids have been shown to reduce inflammation, decrease elevated tryglyceride levels and stimulate visual and neurological development.
Studies conducted by the National Institutes of Health showed that while the optimal ratio of omega-6 to omega-3 may vary depending on the disease being considered, a “lower ratio is more desirable in reducing the risk of many of the chronic diseases” prevalent in Western society.
However, Pruitt emphasized that conventional milk is a safe, nutritious product that delivers the same benefits as organic milk. For consumers looking to increase omega-3 consumption, she recommends tuna and flaxseed as alternative sources if organic milk is too expensive.
“The bottom line is, whether you choose organic or conventional milk, feel confident that you’re receiving a quality product that’s full of nutrition and safe to consume,” Pruitt said. “If you can’t afford organic milk, that’s OK.”