More Fiber, Fewer Deaths: Results of a Major Breast Cancer Prevention Study

Enrolling nearly 49,000 women ages 50 to 79 who didn't have breast cancer, researchers broke them into two groups. Sixty percent upped consumption of fruits and veggies and were tasked with reducing total fat intake to 20 percent of their total daily calories. The control group ate as usual. After 8.5 years, the women who ate less fat and more fiber were 21 percent less likely to have died from breast cancer. (They were also 15 percent less likely to have died from any cause after a breast cancer diagnosis.)

Also interesting: The lower mortality risk from breast cancer was achieved even though the participants weren't able to meet the fat-reduction goals they'd worked on with nutritionists and doctors. What they did achieve was an average fat intake reduction of about 3 percent. (They also lost an average of about 3 percent of their body weight.) The participants’ diet plateau wasn't all bad, however. “That really tells us with these small changes that are doable you can still significantly move the needle in preventing breast cancer-related death,” Iyengar says.

The women who were asked to cut fat in their diet and add fruits and vegetables followed an approach very close to the DASH (dietary approaches to stop hypertension) diet, originally developed to help lower blood pressure, researchers reported. The DASH diet and better-known Mediterranean diet have many similarities.

Some doctors responding to the news pointed out that it took quite a while — 20 years — for the mortality difference between the groups to appear (the participants were tracked for that long even though they stopped altering and recording their diets after 8.5 years). The diet shift also did not lower the risk of developing breast cancer in the first place, which the study had actually been designed to measure.

Iyengar says the study is “really the launch pad” to other research that might better indicate how to use lifestyle factors to reduce the risk of breast cancer mortality. Everything from developing diets and exercise plans that match “a particular type of tumor biology” to tweaking the “dose exposure” of diet and exercise could be important future considerations, he says.