Does Diet Affect Breast Cancer Risk?

Breast cancer is the second leading cause of cancer death in women, and 1 in 8 women in the United States develop breast cancer in her lifetime. Mechanistic research provides convincing support for the hypothesis that a diet rich in fruits and vegetables reduces the risk of developing breast cancer. In contrast, results from observational and case-control studies are inconsistent. There may be several reasons for these weak and inconsistent results: measurement error, analysis of blood biomarkers as a surrogate for breast, and the developmental time period assessed. Specifically, most epidemiologic studies examine the effects of diet in later adulthood on subsequent breast cancer risk. However, earlier time points in breast development represent critical windows during which environmental exposures may influence breast cancer risk. In an attempt to circumvent these limitations, we conducted a randomized dietary intervention study, characterized by increased fruit and vegetable intake, in breastfeeding women. Breast milk samples were collected at baseline (pre-intervention) and at 12 weeks (post-intervention). Breast milk provides an ideal opportunity to assess the link between diet and breast health, as it contains secreted proteins and exfoliated breast epithelial cells—both of which may be used to analyze biomarkers of breast cancer risk. In this pilot study, five women in the intervention group were provided with weekly boxes of fresh fruits and vegetables, tailored nutritional counseling, and asked to maintain weekly food journals. Analysis of weekly journals and breast milk samples collected at baseline and 12 weeks from women in the intervention and control groups demonstrate that is it feasible to significantly increase fruit and vegetable intake in breastfeeding women, and also possible to alter the inflammatory profile of the breast through diet.