LONG-TERM RESPONSES OF WOMEN TO INDOLE-3-CARBINOL OR A HIGH-FIBER DIET

We test the hypothesis that the estrogen metabolite ratio 2-OH-estrone :estriol can be raised via dietary indole-3-carbinol (13C) and that th is higher ratio can be sustained over a 3-month test period. We also e xplore the possible role. of pure fiber on estradiol metabolism. Using a randomized clinical trial with three arms, each containing 20 subje cts, arm 1 received 400 mg/day of 13C daily for 3 months, arm 2 receiv ed 20 g of alpha-cellulose daily for the same time period as a source of added fiber, and arm 3 received a placebo dose. Blood levels of a v ariety of biochemical parameters were measured. The urinary 2-OH-estro ne:estriol estrogen metabolite ratio was measured monthly at the same time of the menstrual cycle. While no changes were observed in the con trol and alpha-cellulose-treated arms, a substantial mean increase in the ratio was observed in the 13C-treated arm at month 1; that increas e was maintained over the 3-month time period. Three of the 20 subject s in this 13C-treated group differed from the others in that no signif icant change in the metabolite ratio was observed at any time point. T he results suggest that 13C can serve to increase the 2-OH-estrone:est riol metabolite ratio in a sustained manner without detectable side ef fects and that some individuals may be resistant to such change.