Could Reducing Fat and Increasing Whole Food Components Lower Breast Cancer Mortality Risk?

It is no big surprise to hear that reducing fat and eating more fruits and vegetables is an excellent health plan. A new study from the Women’s Health Initiative, however, indicates that women who do so may be at a lower risk for breast cancer than those who eat diets with higher fat content.  

The new long-term, federally-funded clinical trial involved nearly 49,000 women between the ages of 50 and 79.  it is the first fully randomized and controlled trial to prove the relationship between diet and breast cancer mortality risk. Researchers found that those women who reduced the fat to no more than 25 percent of their diet—and also added more fruits, vegetables, and whole grains—were at a 21 percent lower risk of death from breast cancer. 

In addition, the women who followed this lower fat diet were also at a 15 percent lower risk of death from any cause (after receiving their breast cancer diagnosis). 

The study looked at data from 48,835 postmenopausal women, collected between 1993 and 1998. These women had no history of breast cancer but were assigned one of two groups.  The first group was instructed to follow a diet in which fat accounted for at least 32 percent of the daily calories.  The second group was instructed to lower their fat intake to no more than 20 percent of their daily calories, and to eat at least one serving of fruit, one serving of vegetable, and one serving whole grain per day.

Furthermore, the women of the low-fat group was instructed followed their regimens for 8.5 years.  Over this time, this group managed to successfully reduce their fat intake to only 25 percent of their daily calories.  As a result, it seems, they also experienced an average weight loss of 3 percent. 

While the results are certainly promising, some experts argue that the size of the trial and the length of its follow-up make it hard to know what instigated the health change.  Rather, it is not clear whether the benefit came only as a result of consuming lower fat content or from increasing whole food components (fruit, vegetable, grain).  

The results of this study will be presented at the annual meeting of the American Society of Clinical Oncology, in Chicago, in June.