Treat yourself to that whole milk Greek yogurt, because a thorough new study by a team of public health researchers and physicians has concluded that the widespread demonization of full-fat dairy is both unjustified and downright inaccurate.

“Our findings not only support, but also significantly strengthen, the growing body of evidence that suggests that dairy fat, contrary to popular belief, does not increase risk of heart disease or overall mortality in older adults," lead author Marcia Otto stated. “In addition to not contributing to death, the results suggest that one fatty acid present in dairy may lower risk of death from cardiovascular disease, particularly from stroke.” 

Writing in The American Journal of Clinical Nutrition, Otto and her colleagues explain that dairy fat’s bad reputation was born when scientific investigations first linked increased blood cholesterol levels to heightened risk of cardiovascular disease many decades ago. Milk products contain a good deal of the LDL cholesterol (aka ‘bad’ cholesterol)-boosting saturated fat palmitic acid.

However, this molecule has since been shown to increase HDL (‘good’) cholesterol, and milk is also composed of several types of healthy medium-chain fatty acids and fat-soluble nutrients that are reduced during the process of making low-fat products.

But proving the benefit of milk fat – or at least dispelling that it is harmful – has been challenging, as many past nutrition studies on the subject have relied on correlations made between subjects’ self-reported food intake data and specific medical outcomes – a design that cannot reveal causation.

With the aim of conducting the first examination of dairy fat’s long-term health effects using objective measurements, the authors followed 2,907 disease-free Americans aged 65 years and older for 22 years, performing blood tests for the level of the three main milk fatty acids at the onset (occurring in 1992 to 1993), year six, and year 13. At the starting point, each subject was also surveyed for lifestyle, medical history, and current medical status, and their information was updated every six months through the year 2000 and every two years thereafter.

Over the course of the study, 833 of the 2,428 deaths were due to CVD, yet an analysis showed that subjects’ blood levels of the odd-chain saturated pentadecanoic and heptadecanoic fatty acids and naturally occurring trans fatty acid trans-palmitoleic were not associated with overall mortality in either men or women.

In contrast, as levels of heptadecanoic acid went up, risk of CVD was seen to go down. For stroke specifically, subjects with the highest levels had a 42 percent lower risk compared with those who had the lowest levels. But curiously, heptadecanoic acid was also linked to a 27 percent higher risk of general non-CVD mortality – an outcome that the team believes warrants further investigation.  

If you are still reticent to abandon your skimmed milk on the grounds that fewer calories=healthier, bear in mind that other recent studies have begun to dispel that misconception as well. The sugar added to make reduced-fat dairy products palatable may be significantly worse in the long term by increasing the chances of metabolic disorders like diabetes, and the lack of fats reduced the duration of time you feel satiated, ultimately leading to higher food intake.

“Consumers have been exposed to so much different and conflicting information about diet, particularly in relation to fats,” she said. “It’s therefore important to have robust studies, so people can make more balanced and informed choices based on scientific fact rather than hearsay,” Otto added.