Macronutrient intake and estrogen metabolism in healthy postmenopausal women

The purpose of this study was to determine if dietary factors could bias es timates of the relationships between estrogen metabolites and breast cancer risk factors. A lower ratio of urinary 2-hydroxyestrone/16 alpha -hydroxye strone (2/16) has been associated with breast cancer diagnosis. However, bo th estrogen metabolism and breast cancer risk have been associated with die tary intake, and breast cancer patients may have different dietary patterns than healthy controls. An association between urinary 2/16 levels and brea st cancer risk may be due to transitory dietary change after diagnosis, or due to other breast cancer risk factors which have been associated to stero id hormone metabolism. Thirty- seven healthy postmenopausal women provided two 24-h urine samples at a two-week interval. Six 24-h diet recalls were a dministered in this same time period. In linear regression analysis, dietar y fat-to-fiber ratio (fat/fiber) and the saturated fat/soluble fiber ratio was inversely associated with urinary 2/16 values (b = -0.22, 95% CI (-0.43 , -0.01; b = -0.26, 95% CI (-0.43, -0.09), respectively). The effects of th ese dietary factors on 2/16 were independent of body mass index or other br east cancer risk factors. These study results suggest that some of the vari ation in estrogen metabolite levels among postmenopausal Caucasian women ma y be due to dietary intake, and that dietary factors should be carefully me asured and evaluated when investigating the relationship between estrogen m etabolites and breast cancer risk.