Changes in dietary fat and fiber and serum hormone concentrations: nutritional strategies for breast cancer prevention over the life course.

The association between dietary fat intake and breast cancer risk has appeared in a meta-analysis of epidemiologic research, migration studies from countries of low to high risk for breast cancer, and animal experiments. With this background, dietary intervention research aims to reduce fat intake and increase fruit, vegetable, and fiber intake, relying on changes in hormone concentrations as biomarkers for reduction in risk of breast cancer. To date, this dietary intervention research spans the life course and has demonstrated stellar success in some studies but sobering results in others. The purpose of this article is to review the intervention research since a 1999 meta-analysis that reported reduced estradiol levels on a low-fat diet and to explore the lessons learned from intervention research on changes in dietary fat and fiber intake and serum hormone concentrations. Secular trends in obesity and ages at pubertal onset and menarche provide dynamic behavioral, genetic, and developmental challenges to the success of dietary prevention. The goal is to formulate an integrative approach to dietary intervention, taking into consideration ethnic group differences in energy expenditure that modulate weight and hormones influencing breast cancer risk over the life course.