How changing a cow's diet can produce healthier milk, cheese, butter

A study is suggesting alterations to a dairy cow’s diet can result in milk lower in saturated fat. The new research reports on a clinical trial in humans demonstrating these natural “healthier” dairy products lead to positive heart health effects, however, some experts note the benefits of the novel cheese, butter and milk products are modest at best.

Scientists have known for some time that changes to a cow’s diet can result in milk with lower levels of saturated fats. In this case, supplementing the animals' diet with a type of sunflower oil can lead to milk higher in healthier monounsaturated fats (of the kind found in olive oils and avocados) and lower in saturated fats.

“Dairy foods contain saturated fat, high intakes of which are associated with increased cardiovascular disease events such as heart attacks,” explains Julie Lovegrove, one of the authors on the new study from the University of Reading. “However, previous studies have shown that diets higher in some dairy foods are not linked with cardiovascular disease, possibly due to other beneficial components of dairy including proteins and calcium. By replacing a quarter of the saturated fat in milk with monounsaturated fat, we have been able to naturally produce healthier dairy foods.”

The new research is one of the first to test the health benefits of this kind of modified dairy product in rigorous clinical trial conditions. Fifty-four subjects, classified as having moderate risk of cardiovascular disease, were recruited for a placebo-controlled crossover study.

After a 12-week period the trial found those consuming a diet high in standard dairy products displayed an average 5.5 percent increase in blood LDL cholesterol levels, compared to those subjects consuming the modified dairy products.

“We are delighted to see that our study showed favorable effects of the modified dairy products naturally lower in saturated fat on blood LDL cholesterol levels and blood vessel health compared with conventional dairy products,” says Lovegrove.

While experts not affiliated with this new study have commended it as rigorous and well-conducted, questions have been raised over exactly how clinically significant its results may be. Duane Mellor, from Aston University, points out the study may be academically interesting, but it is unclear how meaningful its results are to humans in the real-world.

“It is also important to consider although difference in the LDL between the two groups was mathematically or statistically significant, it is perhaps not clinically that important,” says Mellor. “Dietary changes can lower it by over 25 percent and drugs much more. Although the study showed estimated LDL cholesterol changed using an equation, it was unclear how it actually changed as the different types of cholesterol particles based on size did not change.”

Hugo Pedder, from the University of Bristol, affirms the study’s results as “promising,” but also cautiously points out a number of limitations in the trial’s design, including testing a diet that is generally much higher in dairy and fat than most people would consume.

“The trial was relatively short, and only investigated blood markers to measure the impact of the modified diet on cardiovascular disease,” Pedder also suggests. “We aren’t yet sure if this would have meaningful beneficial impacts on cardiovascular health in the long run.”

A great deal of prior study has shown small interventions in livestock diets can lead to notable improvements in methane emissions. Ian Givens, Director of the Institute of Food, Nutrition and Health at the University of Reading, suggests this new research adds to earlier work demonstrating how small dietary interventions in animals can lead to healthier and more environmentally friendly dairy products.

“Through the RESET project, we have been able to successfully reduce the amount of saturated fats and increase monounsaturated fats in otherwise entirely normal dairy products through changing the cow’s diet, without any change in flavor,” says Givens. “Now in this study, we have demonstrated how using this milk to produce cheese, butter and UHT milk can be more beneficial than conventional dairy products on cardiovascular health in those with slightly higher risk of cardiovascular disease.”

The new study was published in the American Journal of Clinical Nutrition.

Source: University of Reading