Diet and the excretion and enterohepatic cycling of estrogens.

Urinary and fecal excretion and plasma levels of estrogens were measured in pre- and postmenopausal women eating different diets. When premenopausal U.S. women eating a "Western diet," comprising high fat (40% of calories) and low fiber, were compared with age-matched vegetarians eating a moderate-fat (30%), high-fiber diet, it was found that the vegetarians excreted threefold more estrogen in their feces, had lower urinary excretion, and had 15-20% lower plasma estrogen levels. When U.S. pre- and postmenopausal women eating a Western diet were compared with recent Asian immigrants eating a very low-fat diet (20-25% of calories), similar results were obtained except that plasma estrogen levels were 30% lower among Orientals compared with those among Western omnivore women. Correlation analysis of dietary components and plasma estrogen showed that plasma estrogen was positively associated with fat and was negatively associated with fiber. The results indicate that diet can alter the route of excretion of estrogen by influencing the enterohepatic circulation and that this, in turn, influences plasma estrogen levels.