Dr. Hendrix leads study at WSU School of Medicine

A major study including nearly 50,000 women followed over eight years indicates that a diet low in fat, but high in fruit, vegetables and grains, does not significantly reduce the risk of breast cancer, colorectal cancer or cardiovascular disease in postmenopausal women, according to a study published in the Feb. 8 issue of JAMA by Susan Hendrix, D.O., WSU professor of obstetrics and gynecology, and her colleagues in the National Institutes of Health Women's Health Initiative.

"This is not permission to go to your local fast food restaurant and eat anything you want," Dr. Hendrix said. "But this study shows us that a low-fat diet is not going to be able to reduce risk."

The Women's Health Initiative Dietary Modification Trial examined the effect of a low-fat diet on the incidence of breast cancer. The WHI, which began in 1992 with 48,835 postmenopausal women without prior breast cancer, included a dietary modification intervention consisting of consumption of a reduced amount of fat (20 percent of energy) and of an increased amount of vegetables and fruits (5 or more servings a day) and grains (6 or more servings a day). The women, aged 50 to 79 years, were randomly assigned to the dietary modification intervention group (40 percent, or 19,541) or the comparison group, who were not asked to make dietary modifications (60 percent, or 29,294). It has been hypothesized that a low-fat diet can reduce breast cancer risk, but previous studies have had mixed results.

The average follow-up time was 8.1 years. Overall, 655 (3.35 percent) women in the intervention group and 1,072 (3.66 percent) women in the comparison group developed invasive breast cancer during follow-up.

The researchers found that there were 201 cases of invasive colorectal cancer (0.13 percent per year) in the intervention group and 279 (0.12 percent) in the comparison group. The WHI low-fat eating pattern intervention did not reduce the risk of invasive colorectal cancers. There was no evidence of reduced risk for any category of colorectal cancer outcome associated with the intervention.

Levels of low-density lipoprotein cholesterol and diastolic blood pressure were significantly reduced. Levels of high-density lipoprotein cholesterol, triglycerides, glucose and insulin did not significantly differ in the intervention vs. comparison groups. The researchers found that the diet had no significant effects on incidence of coronary heart disease, stroke, cardiovascular disease or heart attack. Trends toward greater reductions in coronary heart disease risk were observed in those with lower intakes of saturated fat or trans fat or higher intakes of vegetables/fruits.

For more information or to read the study, please visit http://jama.ama-assn.org/cgi/content/full/295/6/629.