Yogurt consumption and estrogen metabolism in healthy premenopausal women

Dietary modification of intestinal microflora by yogurt or Lactobacilli sup plementation has been shown to decrease fecal beta-glucuronidase activity, thereby possibly affecting estrogen metabolism and lowering breast cancer r isk. To determine if yogurt consumption modifies fecal beta-glucuronidase a ctivity and plasma and urine estrogen concentrations, 16 women (24.8 +/- 1. 0 y; mean +/- SEM) were assigned randomly to two groups, control (CON;n=7) or yogurt treatment (YOG;n=9). Control subjects refrained from yogurt consu mption for three months, whereas the YOG group consumed two cups (454 g/d) of commercially produced yogurt made with a culture (1:1 ratio) of Lactobac illus delbrueckii ssp bulgaricus and Lactococcus salivarius ssp thermophilu s (>10(7) colony forming units/g yogurt) for three consecutive months. Prio r yogurt consumption did not exceed 4-6 cups/month and subjects consumed th eir usual diets during the study. Three-day diet records, fasting mid-lutea l blood, and 24 h urine collections were obtained during three consecutive days of subjects' first-, second-, and fourth-menstrual cycles. Fecal sampl es were collected once during each menstrual cycle. Dietary nutrient intake s were not significantly different within or between groups throughout the study. The YOG group was consuming a low-fat diet (19-22% of total calories ). Fecal beta-glucuronidase activity and plasma and urinary estrone and est radiol-17 beta concentrations were assessed following baseline and months o ne and three for CON and YOG consumers. No significant differences were obs erved within or between groups for any of the aforementioned biochemical va riables. In conclusion, three months of yogurt consumption did not alter fe cal beta-glucuronidase activity or plasma and urine estrogen concentrations . (C) 1999 Elsevier Science Inc.