A large randomized clinical trial found that postmenopausal women who stayed on a low fat diet for 8 years had a reduced risk of death from invasive breast cancers and improved survival rates compared with women who did not follow the dietary regimen.1 The study was presented at a clinical trial plenary session at the American Association for Cancer Research Annual Meeting, held April 16-20, 2016 in New Orleans, Louisiana.

This analysis used data from 48,835 postmenopausal women who participated in the randomized, controlled, dietary modification trial that was part of the Women’s Health Initiative. Though an association between dietary fat intake and breast cancer has been observed for about half a century, this study sought to clarify the effects of a low-fat dietary pattern on breast cancer.

The participating women were age 50 to 79 years, had no prior breast cancer, normal mammograms, and normal dietary fat intake. Of those, 19,541 women were put on a low-fat diet with nutritionist-led group sessions that sought to reduce fat intake reduction to 20% of energy and increase the consumption of fruits, vegetables, and grain. The other 29,294 women in the trial followed their usual dietary patterns.

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After about 8 years of remaining on the low fat diet, 1,767 of the women were diagnosed with breast cancer. Researchers found the breast cancer overall survival from diagnosis was higher in the dietary group: 82% versus 78%. The researchers said this reduction is due, in part, to better survival following breast cancer diagnosis.

“This was the first time we had examined the deaths after breast cancer among this group, and we found that a sustained low-fat diet increased the survival rates among postmenopausal women after a breast cancer diagnosis,” said presenting author Rowan Chlebowski, MD, PhD, of the Los Angeles Biomedical Research Institute in California. “The study also suggests that women would need to remain on the low fat diets to maintain the benefits of the dietary intervention.”

The 2 groups of women had similar breast cancer characteristics, including size, nodal status, and distribution of poor prognosis, triple-negative cancers and HER2-positive cancers. However, the dietary group had fewer progesterone-receptor-negative cancers (28.4% versus 33%). In addition, researchers noted lower cardiovascular disease mortality in the dietary group.


1. Chlebowski RT, Aragaki AK, Anderson GL, et al. Low-fat dietary pattern and breast cancer mortality in the Women’s Health Initiative (WHI) randomized trial. Abstract CT043. Presented at American Association for Cancer Research Annual Meeting, held April 16-20, 2016 in New Orleans, Louisiana.