The Surprising Benefits of Full-Fat Dairy

(This article appeared previously on Grandparents.com)

For decades, the word on milk and other dairy products has been simple: Drink skim. But a recent study from Tufts University suggests this dietary dogma may need to go.

For the study, researchers analyzed blood samples taken over a 15-year period from more than 3,300 nurses in the ongoing Nurses’ Health Study. Women whose blood contained high levels of several by-products of full-fat diary had a 46 percent lower risk of developing diabetes than those with low levels.

This finding, though counterintuitive, didn’t come as a surprise — at least to the nutrition experts involved. “This is now the third recent study in which we’ve found that people with higher biomarkers of dairy fat consumption in their blood have substantially lower risk of type 2 diabetes, with risk cut about half,” says study author Dr. Dariush Mozaffarian, dean of the Tufts Friedman School of Nutrition Science & Policy and the Jean Mayer Chair and professor of nutrition. “Three other independent groups have found the same thing. The consistency and size of the effect are pretty remarkable.”

In fact, in another recent study, based on data from the Women’s Health Study, Brigham and Women’s Hospital and Harvard University researchers found that full-fat dairy protected participants from obesity. Among the more than 18,000 women enrolled, those who consumed the most full-fat dairy lowered their risk of being overweight or obese by 8 percent.

“In just the last few years,” Mozaffarian adds, “a range of studies have found that whole-fat dairy has no links to weight gain or cardiovascular disease in adults, may lower risk of diabetes in adults and may lead to less weight gain in children.”

Mozaffarian and other nutrition researchers say current dietary guidelines reflect the theory that people need to reduce their fat intake in order to lower their body weight. But they don’t take into account the fact that when people cut out one component of the diet, they tend to over-consume others. When people cut fat from their diets, they consume more carbohydrates and sugars, which get stored as body fat.

“We know from both long-term observational studies and random control trials that fat content of the diet or foods is not related to weight gain,” Mozaffarian says. “Yet this myth persists.”

How full fat milk and other dairy lead to better health isn’t fully understood, but they could be due to benefits of other components of foods high in dairy fat. For instance, the fermentation of cheese may have a positive effect on nutrients or on the gut microbiome. Or the specific fatty acids in dairy fat may have direct effects on health. It could simply be that eating whole-fat dairy replaces calories from starches and sugar. “More research is needed,” Mozaffarian says.

For the moment, USDA dietary guidelines continue to promote the low-fat approach. But Mozaffarian says, it still may be too soon to reverse course on dairy consumption. “The accumulating evidence is not yet strong enough to recommend only whole-fat dairy, but it is even weaker to advise only low-fat dairy,” he says.

Guidelines should be neutral on dairy fat, letting people make their own choice, he suggests. “More important is to select a mix of different dairy foods,” he says, “and especially to include yogurt and cheese, as these are different foods with potentially complementary health benefits.”