Feb. 13, 2001 -- Americans have been bombarded by claims that pumping more fruits and veggies into your diet will protect against cancer. Although fruits and vegetables certainly aren't bad for you, researchers now say they can find little proof that any particular fruit or vegetable has any effect on preventing breast cancer in women.
Some studies have reported that eating fruits and vegetables may cut the risk of breast cancer by 25% or more. But Harvard researcher Stephanie A. Smith-Warner, PhD, combed the medical literature and found an overall decrease in risk of only about 3-9%.
Her study appears in the Feb. 14 issue of The Journal of the American Medical Association. Smith-Warner and colleagues say they don't want to discourage women from eating healthy foods, but they do want them to know that the most effective ways of protecting yourself from breast cancer don't come from food.
On the other hand, fruits and vegetables -- especially green, leafy vegetables -- do seem to help lower the risk of other cancers and of heart disease. They also may help you avoid obesity, which is a contributing factor in many serious diseases.
"Continuing to eat fruits and vegetables is an important part of a healthy diet; however, other strategies need to be identified to try and reduce breast cancer risk," Smith-Warner tells WebMD.
Martha L. Slattery, PhD, says the new study throws into question current recommendations to eat five servings of fruit and vegetables per day. The National Cancer Institute says there is a direct relationship between a high fruit and vegetable diet and lower risk of certain cancers.
Slattery, of the University of Utah, tells WebMD that eating five servings a day probably isn't harmful, but she thinks more work should be done to try to determine if specific vegetables or fruits offer protection against certain cancers.
She notes that many of the studies that have been conducted on this topic involved asking women a series of questions about what they typically eat, but she says the questions may not have been as specific as they need to be in order to see a benefit from certain individual foods or combinations of foods.
Slattery says it's also possible that more than five servings a day of certain fruits and vegetables are required to reduce your risk of some cancers.
"I'm not sure how they even came up with five a day [as a recommendation], because most of the literature actually supports more than five a day for prevention," Slattery says. In addition, many of the studies showing significant prevention involved supplements, not actual fruit and vegetable consumption, she says.
Like Smith-Warner, Slattery says that even though fruits and veggies apparently can't reduce your risk of breast cancer, there are plenty of other good reasons to eat them.
"It makes sense to watch your weight and to try to be physically active and watch your diet," she says. "Those things do contribute to overall health ... and fruits and vegetables certainly don't hurt you."