CHICAGO – Hopes that a diet low in fat and chock-full of fruits and vegetables could prevent the return of breast cancer were dashed Tuesday by a large, seven-year experiment in more than 3,000 women.
The government study found no benefit from a mega-vegetable-and-fruit diet over the U.S. recommended servings of five fruits and vegetables a day – more than most Americans get.
“It sends us back to the drawing board,” said Susan Gapstur of Northwestern University’s Feinberg School of Medicine, who wasn’t involved in the new study but co-wrote an accompanying editorial in the journal.
“Should we really have focused on dietary components like fruits, vegetables and fat?” Gapstur asked. “Or should we be focusing, in addition to diet, on lifestyle factors including physical activity and weight?”
For now, the message for the 2.4 million breast cancer survivors in the United States is that they don’t need to go overboard on fruit and veggies, researchers said.
The experiment involved almost 3,100 women who had been successfully treated for early stage breast cancer. Their average age was 53 when the study began.
About half the women were randomly assigned to a daily diet that included five vegetable servings, three fruit servings, 16 ounces of vegetable juice and 30 grams of fiber. On average, they ate 13 percent less in fat calories than did the comparison group.
The comparison half was assigned to get educational materials about the importance of eating five servings of fruits and vegetables a day.
After one year, women on the high-vegetable diet had 73 percent higher blood levels of pigments found in fruits and vegetables than the other women, indicating they were truthful about how many fruits and vegetables they ate, researchers said.
During the next seven years, the cancer returned in about the same proportion of women in both groups: 256 women (16.7 percent) of the women on the special diet and 262 women (16.9 percent) in the comparison group. About 10 percent of both groups died during that time, most of them from breast cancer.
The study appears in today’s Journal of the American Medical Association.
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