The disappointing finding comes from a seven-year study of more than 3,000 women successfully treated for early breast cancer.
University of California, San Diego cancer researcher John P. Pierce, PhD, and colleagues urged half the women to eat the "5-A-Day" servings of fruits and vegetables recommended by the National Cancer Institute. The other half of the women underwent intensive training to get them to eat even more of these healthy foods.
"We got people up to 12 servings of fruits and vegetables a day," Pierce tells WebMD. "So how extreme do you need to go? If you take five servings a day, do you need to go over the top? The answer is no. But this doesn't mean you should not eat your 5-A-Day."
After trying to follow their diets for more than seven years, 17% of the women in each group saw their cancer return, and 10% in each group died.
Pierce and colleagues report their findings in the July 18 issue of TheJournal of the American Medical Association. An editorial by Susan M. Gapstur, PhD, associate director for cancer prevention and control at the Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, accompanies the study.
Gapstur and Pierce agree that the study showed no added breast cancer survival benefit from adding extra servings of fruits and vegetables.
Gapstur notes that while the women seemed to eat a lot of healthy foods, they also ate more fats than they were supposed to.
"While it did appear the fruit and vegetable intake increased, clearly the self-reported total diet and fat intake didn't achieve its goal," Gapstur tells WebMD. "The dietary fat intake did not improve. In fact, the women seemed to be eating a higher quantity of fat at the end of the study than they were at the start."
Pierce points to an earlier report on these women in the June 10 issue of the Journal of Clinical Oncology. That study found that regardless of whether they were obese, breast cancer survivors who followed the 5-A-Day diet -- and exercised about 30 minutes a day -- had significantly improved cancer-free survival.
"Eat five servings of fruits and vegetables and exercise daily -- those are the things that matter for breast cancer survival," Pierce says.
Gapstur agrees that's good advice.
"If I were a breast cancer survivor, I would want to know more about the benefits of energy balance and exercise," she says. "It is really not about consuming two more servings of vegetables every day. It is about changing my lifestyle so I can live a healthier and longer life."
- If you’re in the early stages of breast cancer and need support, you can find other women like you on WebMD’s Breast Cancer: Friend to Friend message board.