THE EFFECT OF DIETARY-FAT AND FIBER ON SERUM ESTROGEN CONCENTRATIONS IN PREMENOPAUSAL WOMEN UNDER CONTROLLED DIETARY CONDITIONS

The effect of dietary fiber and fat on serum sex hormones was studied in premenopausal women. After an initial control period during which t he diet was high in fat (40% of calories as fat) and low in fiber (12 g/day), the amounts of fat and fiber were varied in the setting of a m etabolic kitchen and carefully monitored meals. Forty-eight women comp leted 58 protocols. When the diet was changed to low-fat (20-25% calor ies as fat) and high fiber (40 g/day), there were significant decrease s in serum concentrations of estrone, estrone sulfate, testosterone, a ndrostenedione, and sex hormone binding globulin (SHBG) and near signi ficant decreases in estradiol and free estradiol. When independent eff ects were examined, high fiber alone caused a decrease in estradiol an d SHBG, whereas fat and fiber caused the observed decrease in estrone sulfate. Dietary fat independently influenced the serum concentration of androstenedione. Increased dietary fiber caused a lengthening of th e menstrual cycle by 0.72 day and a lengthening of the follicular phas e by 0.85 day.