A recent Women’s Health Initiative study, published in the Journal of the American Medical Association (JAMA), suggested that low-fat diets may not protect women against the risk of breast cancer, colon cancer or even heart disease. The federally-funded study monitored the fat intake of 50,000 American women ages 50 to 79 for an average of eight years.
The study’s findings contradict what many have long believed is the foundation of a healthy lifestyle, leaving many experts worried that the public will misconstrue the information. In an article in the Washington Post, Walter Willett, professor of epidemiology and nutrition at the Harvard School of Public Health, said, “it would be a huge misinterpretation to believe that it doesn't matter what we eat to prevent heart disease and cancer.” Sharonne Hayes, MD, director of the Women's Heart Clinic at Mayo Clinic, adds, “eating the right fats is what counts.”
We asked our team of experts what this study means for you. Here are their thoughts on these controversial findings:
“The conclusion of this study, at least as portrayed by the press, is both limited and misleading. Simply lowering total fat is not a particularly helpful intervention by itself as shown by the results. The more important intervention would be to prescribe a comprehensive whole foods diet (not just to add a few vegetables), decrease saturated fats, increase essential omega 3 fatty acids, and decrease total calories and portion size. It is also important both to educate and support the women so they actually make these dietary changes. Dietary recall is often not very accurate. As noted by other commentators, good health also requires exercise and attention to stress management.”
– Susan Lord, MD
The Center for Mind-Body Medicine
“Lumping all fats together is like talking about all carbs as being equal. The study failed to distinguish between "good fats" and "bad fats." A plethora of research suggests that trans fats and saturated fats are health harmful, but olive oil, fish oil and nuts are health protective. The researchers need to look in more depth at the types of fats consumed, and not just look at total fat intake.”
– Nancy Clark, MS, RD
Sports Nutrition Services, Healthworks Fitness Center
“The media has characterized the study as showing that adopting a "low" fat diet has been shown to have little benefit. In fact, the participants in the special intervention diet condition were unable to reach the goal of 20% of calories from fat diet. The best they could do in the first year of the trial was 24% and by the end of the trial their average fat consumption was 29%. The U.S. average is 33%. But the Asian dietary pattern that has been most strongly associated with reduced risk of breast cancer and heart disease is 15% of calories from fat. In fact, in the 65 Counties Study in China that was conducted by Richard Peto, Colin Campbell and Junshi Chen (Junshi, Chen, T. Colin Campbell, Li Junyao, and Richard Peto, Diet, Life-style and Mortality in China: A Study of the Characteristics of 65 Chinese Counties, Oxford: Oxford University Press, 1990, p. 6.), the HIGHEST average fat consumption found in ANY county in China was 25%. So how is 29% of calories from fat considered to be a "low" level when it is higher than the highest fat intake in all of China?
The JAMA article first-authored by Ross Prentice is being misinterpreted as evidence that a low-fat diet does not reduce breast cancer risk or cardiovascular disease risk or colon cancer risk. The more appropriate conclusion is that the study showed that it is difficult to get U.S. women to adhere to a diet as low in fat as the traditional Japanese or Chinese diet. The study did show, for the few women who successfully dropped their fat intake the most and kept it lower, a significant decreased risk of breast cancer. That's a pretty tepid affirmation of the hypothesis driving the study but it is certainly not the disconfirmation of the hypothesis that comes across in media discussions about the study.”
– Bill McCarthy, PhD
UCLA School of