Dietary and hormonal evaluation of men at different risks for prostate cancer: fiber intake, excretion, and composition, with in vitro evidence for an association between steroid hormones and specific fiber components.

Dietary fiber intake and fecal fiber excretion were investigated in 53 Seventh-day Adventist men: 18 nonvegetarians (NVs), 20 lactoovovegetarians (LOVs), and 15 vegans (Vs). Three-day composite diets and stools were analyzed for neutral detergent fiber (NDF), hemicellulose, cellulose, lignin, and pectin. In vitro binding of estrone (E1), estradiol-17 beta (E2), and testosterone (T) to a water-insoluble fiber fraction obtained from these diets was correlated with the intake of specific dietary fiber components. Vs consumed and excreted significantly more of all fiber components than did LOVs or NVs. LOVs consumed more of all fiber components (except cellulose) than did omnivores and excreted more NDF, hemicellulose, and cellulose. Dietary lignin was positively correlated with T binding in the V group. There were significant relationships for all groups combined between lignin and water-insoluble fiber binding of E1, E2, and T. Further study is needed to clarify relationships between fiber components, steroid-hormone metabolism, and risk of prostate cancer.