EFFECTS OF DIET SUPPLEMENTATION WITH WHEAT BRAN ON SERUM ESTROGEN-LEVELS IN THE FOLLICULAR AND LUTEAL PHASES OF THE MENSTRUAL-CYCLE

There is both epidemiologic and experimental support for the hypothesi s that a high-fiber diet can reduce breast cancer risk; this may be du e, at least in part, to a reduction in circulating estrogens. This stu dy examined the effects of three levels of wheat bran supplementation (5, 10, and 20 g/d for 2 mo) on the major serum estrogens during both the luteal and follicular phases of the menstrual cycle. The 10- and 2 0-g supplements, which increased the total dietary fiber intakes to ap proximately 20 and 32 g/d, respectively, resulted in significant decre ases in the luteal serum estrone (P < 0.05 and < 0.02, respectively). The serum estradiol was significantly reduced in the 10-g wheat bran g roup after 2 mo (P < 0.05); the 20-g supplemented group showed a signi ficant decrease in estradiol at 1 mo (P < 0.02), but not at 2 mo. No c hanges occurred in the estrone sulfate concentrations. During the foll icular phase, the 10-g wheat bran group exhibited a significant reduct ion in the serum estrone(P < 0.02). Only the serum estrone sulfate sho wed any reduction with the 20-g supplement, and this just failed to ac hieve significance (P = 0.07). Serum sex hormone-binding globulin leve ls were unaffected by wheat bran. When of long duration, these effects may be sufficient to favorably influence breast cancer risk in Wester n women. (C)Elsevier Science Inc. 1997.