Fruits, vegetables won’t prevent breast cancer
Eat them anyway, say nutritionists
A diet high in fruits and vegetables appears to be unrelated to the risk of breast cancer, according to a Harvard study based on the data from more than 350,000 women in the Pooling Project of Prospective Studies of Diet and Cancer.1 Although this finding contradicts some earlier findings, researchers and nutritionists are quick to point out that patients and health care professionals should not see this study as an indicator that fruit and vegetable consumption is not important.
Earlier studies have attributed high fruit and vegetable consumption to an approximately 25% reduction in the risk for breast cancer. "It is still very important for health care professionals to recommend the inclusion of lots of fruits and vegetable as part of a generally healthy diet," says Stephanie Smith-Warner, PhD, research scientist at the Harvard School of Public Health in Boston.
Confusing findings
Smith-Warner acknowledges that the findings are somewhat confusing since "fruits and vegetables are rich sources of potential cancer-preventing chemicals. "We were surprised how consistent the findings were for total fruit and vegetable intake across all eight of the studies we looked at," she says.
Smith-Warner’s study comes on the heels of two others studies, also done at Harvard, concluding that a low-fat diet does not reduce the risk of breast cancer and that a diet rich in fruits and vegetable doesn’t ward off colorectal cancer.2,3 According to her study, "These results suggest that fruit and vegetable consumption is not associated with breast cancer risk when analyzed as total fruits and vegetables, fruits, fruit juice, total fruits, total vegetables, green leafy vegetables, eight botanically defined fruit and vegetable subgroups, or 17 specific fruits and vegetables."
Smith-Warner says she is concerned that results of her study will be misinterpreted. "Individual studies keep getting reported, but we must look at the total body of evidence, and that’s often lost when individual results are reported."
Wahida Karmally, MS, RD, director of nutrition at the Irving Center for Clinical Research at Columbia Presbyterian Medical Center in New York City, says epidemiological studies such as Smith-Warner’s are important, but often are misinterpreted because of the large numbers of patients tracked. "It’s like saying everybody wearing a blue jacket will get heart disease," she says. "When we get a result like this, it is a signal that this is an area we need to investigate more deeply."
Karmally suggests a deeper look at fruit and vegetable consumption at various stages of life. "It is the responsibility of researchers and the media to see that these kinds of results are translated into lay terminology so that the public will get perspective on the findings," she concludes.
References
1. Smith-Warner SA, Spiegelman D, Yaun SS, et al. Intakes of fruits and vegetables and risk of breast cancer. JAMA 2001; 285:769-776.
2. Holmes MD, Hunter DJ, Colditz GA, et al. Association of dietary intake of fat and fatty acids with risk of breast cancer. JAMA 1999; 281:914-920.
3. Michels KB, Giovannucci E, Joshipura KJ, et al. Prospective study of fruit and vegetable consumption and incidence of colon and rectal cancers. J Natl Cancer Inst 2000; 92:1,740-1,752.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content