Dear Doctor: I just read that full-fat milk isn't actually bad for you, and that it may even reduce the risk of stroke. That's just so different from what we've been taught. What's the deal?
Dear Reader: The results of emerging research in recent years suggest that some of what had been taken as fact regarding the adverse health effects of a range of dietary fats was incorrect. Among the tenets recently called into question is the theory that full-fat dairy products have a direct link to heart disease and stroke.
To understand how deeply this idea has taken root, just take a look at the cheese and dairy cases of your local grocery store. Offerings of nonfat and low-fat milk far outnumber those of whole milk. Ditto for the cream and half-and-half section, which is often dwarfed by a wide selection of fat-free creamlike products. The de-fatting trend has transferred to the cheese and ice cream aisles as well. It's fascinating to read ingredient labels and see the culinary (and chemical) gymnastics used to arrive at some of these low-fat products.
Heart disease is the leading cause of death for both men and women in the United States each year. Small wonder then that the study you're referring to, which disputes the long-held idea that dairy fat raises cardiovascular risk, made such a splash. What added to the collective double-take is that researchers from the Friedman School of Nutrition Science and Policy at Tufts University in Medford, Massachusetts, went on to report that in some instances, full-fat dairy products may even offer health benefits.
Published last summer in The American Journal of Clinical Nutrition, the study contradicts the most recent Dietary Guidelines for Americans. The current guidelines, which are issued by the federal Office of Disease Prevention and Health Promotion, urge Americans to choose dairy products that are low-fat or fat-free.
The study analyzed health data from more than 2,900 women and men aged 65 and older. Researchers began in 1992, with baseline measurements of participants' blood plasma levels of three fatty acids that are contained in dairy products. They followed the study participants for the next 22 years, including periodic rechecks of blood plasma levels. By 2014, a total of 2,428 of the study participants had died. Of those deaths, 833 were attributed to heart disease. However, according to the final analysis of the data, none of the three fatty acids that were the focus of the study were linked to the risk of total mortality. Even more surprising were results that showed participants with higher levels of fatty acids, which suggested higher levels of consumption of whole-fat dairy products, had a 42 percent lower risk of death from stroke.
As the study's authors point out, low-fat dairy products tend to have higher levels of simple sugars, which are now getting a closer look as a factor in cardiovascular disease. It will be interesting to see whether federal dietary guidelines shift as a result of this study, which was funded by the National Institutes of Health.
(Send your questions to firstname.lastname@example.org, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)