If you’re a health-conscious person who enjoys dairy products, you probably tend to reach for low-fat or nonfat versions of milk, yogurt, ice cream and the like over their full-fat counterparts. After all, for years the public health message has been that reduced-fat dairy products are healthier choices. But some recent research findings suggest that whole-fat dairy products just might offer health advantages over less fat or nonfat varieties when it comes to fertility, diabetes risk, and more. It’s too soon to make recommendations based on these limited findings, but the results are, indeed, intriguing.
For example, in a study published in the journal Human Reproduction in 2007, researchers studied the diets of more than 18,555 married, premenopausal women with no history of infertility who became pregnant or tried to get pregnant during an eight-year period. It turned out that women who ate at least two servings of low-fat dairy foods per week had an 85 percent higher risk of anovulatory (failure to ovulate) infertility than those who ate one or less servings per week. And, women who ate at least one serving of high-fat dairy food each day were 27 percent less likely to experience anovulatory infertility than those who ate one or less servings per day. These findings led the researchers to conclude that a high intake of low-fat dairy foods might actually increase the risk of anovulatory infertility, while high-fat dairy intake may decrease risk.
In another study, published in the Annals of Internal Medicine in 2010, researchers measuring plasma levels of insulin, fatty acids, and other health markers in 2,736 adults discovered that whole-fat dairy food consumption was strongly associated with higher plasma levels of trans-palmitoleate, a fatty acid associated with lower insulin resistance (a desirable state) and decreased risk of type II diabetes. In fact, diabetes incidence was 60 percent lower among subjects with the highest levels than among those with the lowest levels.
So, how can these unexpected findings be explained? Differences in the hormone content of high-fat (or whole-fat) and low- or nonfat dairy products seem to be at least partly responsible, says Dr. Victoria Maizes, Executive Director of the Arizona Center for Integrative Medicine and Professor of Medicine, Family and Community Medicine and Public Health at the University of Arizona.
“To make low-fat or nonfat milk, the milk is spun at very high speeds,” Maizes explains. “The attraction of hormones is different for the resulting water aspect [of the milk] versus the fat aspect.” The female hormones from the cow that make their way into milk (estrogen and progesterone) have an affinity for the fat portion, while the male hormones (testosterone, for one) gravitate toward the water portion. As a result, there’s a shift toward male hormones in reduced-fat dairy products, with potential physiological implications that additional research will likely help elucidate.
If you decide to switch to whole-fat dairy in the meantime, keep your portions in check, especially if you’re overweight or obese. These products do contain significant amounts of saturated fat and calories, and some—such as ice cream—tend to be high in sugar. (It’s worth noting, however, that many reduced-fat dairy products contain more added sugar and extra ingredients in order to help compensate for the missing flavor and mouth feel of higher-fat versions.)
Choose organic products whenever possible for the highest quality. And, to find ethically sound suppliers (many of them family farms), check out The Cornucopia Institute (www.cornucopia.org) dairy ratings. It’ll give you another reason to feel good about the moo juice you pour on your cereal.