July 17, 2007

New Study Finds Breast Cancer Survivors Don't Need to Increase Fruits and Vegetables beyond National Guidelines

(240 Oregon and Washington women participate in national study)  

(PORTLAND, Ore.)-July 17, 2007- Eating a diet very high in vegetables, fruit and fiber and low in fat, did not reduce breast cancer recurrence or death in early stage breast cancer survivors, according to a study co-authored by researchers at Kaiser Permanente's Center for Health Research and published in the July 18, 2007 issue of the Journal of the American Medical Association (JAMA). The study is the largest randomized clinical trial to assess the influence of diet on additional breast cancer events.

The results are part of the multi-center Women's Healthy Eating and Living (WHEL) study, coordinated by the Moores Cancer Center at the University of California, San Diego. Participating institutions included the Kaiser Permanente Center for Health Research in Portland, Oregon; the Kaiser Permanente Division of Research in Oakland CA; University of California, Davis; Stanford University; University of Arizona at Tucson, and the University of Texas M.D. Anderson Cancer Center in Houston.

"For the typical woman diagnosed with early stage breast cancer, there is no additional benefit from dramatically increasing consumption of plant-based foods rich in 'cancer preventive' compounds, compared to following the recommended healthy diet," said John Pierce, PhD, director of the Cancer Prevention and Control Program at the Moores UCSD Cancer Center.

"These results do not mean that women should stop paying attention to their diet," said co-author Njeri Karanja, PhD, senior investigator at Kaiser Permanente's Center for Health Research in Portland, Oregon. "Several other controlled trials have found that eating 8-12 fruits and vegetables a day lowers blood pressure which reduces the risk of heart disease and strokes."

The WHEL study followed 3,088 women, aged 18 to 70, for between 6 and 11 years. Participants were randomly assigned to one of two diet groups. The comparison group followed the guidelines promoted by the U.S. Department of Agriculture (USDA), which include five vegetable and fruit servings per day, at least 20 grams of fiber per day and 30% fat.

The intensive intervention group was asked to follow a daily dietary pattern that included 5 vegetable servings, 16 fluid ounces of vegetable juice, 3 fruit servings, 30 grams of fiber and 15-20% of energy from fat.

At the start of the study, both groups consumed similar amounts of vegetables and fruits (7 servings a day on average), fiber and calories form fat. Telephone counseling helped women assigned to the intensive dietary group to change their diets substantially. At the end of the first year of observation, women in the intervention group had increased their vegetable and fruit intake to an average of 12 servings a day. They also increased their fiber intake substantially and decreased fat intake. These large changes in self-reported dietary pattern were validated by large changes in plasma carotenoid concentrations. By the fourth year of the trial, relative to the comparison group, the intensive dietary group was still consuming more vegetable servings (+65%), more fruit servings (+25%), more fiber (+30%), and less energy from fat (-13%). The difference in diets between the two groups was maintained throughout the trial.

After a median of 7 years of follow-up, the study observed no difference in recurrence or survival between groups. About 17% of women in both diet groups developed a breast cancer recurrence or new breast cancer and 10 % of women in both groups died.

"It's important to remember that all of the women in this study ate at least 5 fruits and vegetables a day, more than the average American. By increasing our consumption of these foods, we could make big strides in improving our health," added Karanja, from Kaiser Permanente's Center for Health Research in Portland.

The results do not rule out the possibility that following a diet extremely high in fruits, fiber and low in fat from a young age would be helpful. Further more, researchers will be investigating specific subgroups within this study to determine if any of the women might have received some additional benefit from the dietary change.

This work was initiated with support by the Walton Family Foundation, with the major part of the study supported by grants from the National Cancer Institute.

Kaiser Permanente's Center for Health Research, founded in 1964, is a non-profit research institution dedicated to "advancing knowledge to improve health." Kaiser Permanente is America's leading integrated health care organization. Founded in 1945, the organization serves the health needs of more than 8.5 million people nationwide. About 480,000 people in Oregon and Southwest Washington receive their health care from Kaiser Permanente.

For more infomation contact:

Mary Sawyers - 503-813-3967