Low-fat high-fiber diet decreased serum and urine androgens in men

To validate our hypothesis that reduction in dietary fat may result in changes in androgen metabolism, 39 middle-aged, white, healthy men ( 50 - 60 yr of age) were studied while they were consuming their usual high-fat, low-fiber diet and after 8 wk modulation to an isocaloric low-fat, high-fiber diet. Mean body weight decreased by 1 kg, whereas total caloric intake, energy expenditure, and activity index were not changed. After diet modulation, mean serum testosterone ( T) concentration fell ( P < 0.0001), accompanied by small but significant decreases in serum free T ( P = 0.0045), 5 alpha-dihydrotestosterone ( P = 0.0053), and adrenal androgens (androstendione, P = 0.0135; dehydroepiandrosterone sulfate, P = 0.0011). Serum estradiol and SHBG showed smaller decreases. Parallel decreases in urinary excretion of some testicular and adrenal androgens were demonstrated. Metabolic clearance rates of T were not changed, and production rates for T showed a downward trend while on low-fat diet modulation. We conclude that reduction in dietary fat intake ( and increase in fiber) results in 12% consistent lowering of circulating androgen levels without changing the clearance.