Milk from cattle fed a 100 per cent organic diet had more omega-3 fatty acids, a key element of a healthy diet, than those given a conventional grain diet, it showed.
Dubbed “grassmilk”, it also had an almost even ratio of omega-6 to omega-3, compared with nearly six to one in conventional whole milk.
Consuming too much omega-6 and too little omega-3 can increase the risk of cardiovascular disease, obesity and diabetes.
The findings, published in Food Science & Nutrition, also highlight the health benefits for pregnant and lactating women, and for children.
Co-author Dr Bradley Heins, of the University of Minnesota, said: “With growing demand for organic dairy products, producers may be able to expand their profitability and market share by converting to grass-based pasture and forage-feeding.”
The study, helped by British researchers from the University of Newcastle, looked at nutrient levels in milk from cows managed under three US systems – grassmilk, organic (80 per cent forage-based diet) and conventional.
A healthy omega-3 intake can also slow the loss of cognitive function among the elderly.