(This article was #53 in Discover Magazine’s top 100 stories of 2006.)
The largest-ever experimental study examining whether a low-fat diet can prevent cancer and heart disease brought discouraging results. After following 48,835 postmenopausal women for eight years, scientists concluded that cutting fat from the diet doesn’t significantly reduce the incidence of breast or colorectal cancer, heart disease, or stroke. Results of the $415 million trial, part of the National Institutes of Health’s Women’s Health Initiative, were reported in three papers in the Journal of the American Medical Association.
Revised ideas about the role of fat in disease could help explain the murky data, notes Michael Thun, who heads epidemiological research for the American Cancer Society. For example, women in the study cut their total fat intake rather than specifically targeting saturated fats and trans fats, which are now known to contribute to heart disease risk. Cancer researchers are also starting to focus more on risks from obesity. “The evidence base has become very strong that it’s being fat rather than eating fat that’s associated with risk,” Thun says.
He and others plan to follow the women for an additional five years for more information. Meanwhile, the best advice from experts is to eat less saturated and trans fats and more fruits and vegetables.