The first large, nationwide comparison of organic and conventional milk composition, conducted by Washington State University (WSU), found that organic milk has a healthier ratio of omega-6 to omega-3 fatty acids. Many researchers think a higher intake of omega-3 fatty acids (found in meats and dairy products from grass-fed animals, flaxseed, seafood, walnuts and some leafy greens) reduces the risk of heart disease and, potentially, cancer by offsetting the too-high intake of omega-6 fatty acids in the contemporary U.S. diet. The typical U.S. diet contains a ratio of 10:1 omega-6 to omega-3 fatty acids (the imbalance coming from consuming too much processed and fried food, grain oil, seed oil, and meat and dairy from grain-fed animals), while the ratio should be closer to 4:1 or even 2:1.
The 18-month study on the nutritional qualities of milk, published in the peer-reviewed online journal PLOS ONE, compared nearly 400 samples of organic and non-organic whole milk from 14 commercial milk processors. The study found that organic milk has an omega-6 to omega-3 ratio of 2.28:1 — just about perfect in terms of an optimal diet, according to WSU’s explanation of the findings.
The ratio of omega-fatty acids in conventional milk, according to the study, was up to 2.5 times higher, at about 5.8:1. Researchers attributed the difference in the milks to what the cows ate. Most conventional dairy cows’ diets are made up of ingredients high in omega-6 fatty acids, such as corn and corn silage. Organic dairy cows, by standards set by the USDA National Organic Program, spend a minimum of 120 days per year outside on grass pasture and eat forage-based feeds, such as hay, when grass pasture isn’t available.
“The very large increase in omega-3 fatty acids in organic milk — 62 percent higher than in conventional milk — really surprised the whole research team,” says Charles Benbrook, a program leader with WSU’s Center for Sustaining Agriculture and Natural Resources. “These are the heart-healthy fatty acids that play a critical role during pregnancy and lactation, and as a child grows,” he adds. “The magnitude of the difference is the largest I know of between an organic food and its conventional counterpart.”
Consumers should choose whole organic milk to get the most benefit from this difference. “The omega-3 and omega-6 fatty acids are in the fat portion of the milk,” Benbrook says. “Whole milk is about 3.4 percent butterfat, so if you drink 2 percent instead of whole, you’re giving up about half of that benefit.”