If milk does the heart good, it might do the heart even more good if it comes from dairy cows which grazed on grass instead of on feedlots, according to a recent US study.
Earlier studies showed that cows on a diet of fresh grass produce milk with five times as much of an unsaturated fat called conjugated linoleic acid (CLA) than cows fed processed grains. Studies in animals had suggested that CLAs can protect the heart and aid weight loss. Now Hannia Campos of the Harvard School of Public Health in the US and her colleagues have confirmed in a human study that those with the highest concentrations of CLAs had a 36% lower risk of heart attack compared to those with the lowest concentrations.
The findings held true even when heart disease risk factors such as high blood pressure and smoking were taken into account.
Campos says the new findings, published in The American Journal of Clinical Nutrition in May, suggest that CLA offers heart-healthy benefits that could more than offset the harms of saturated fat in milk. Dairy products in the US come almost exclusively from feedlots, she told Reuters Health, and cow’s milk is the primary source of CLA (beef contains a small amount). So the study looked to Costa Rica, where pasture grazing of dairy cows is still the norm.
According to the Food and Agriculture Organization, India (the world’s largest dairy producer) still relies mainly on grazing, supplemented with fodder crops. This is not entirely grass pasturing, however, and it has been suggested that reliance on feeds is looking inevitable with pasture land dwindling.