title: Urinary estrogen metabolites during a randomized soy trial.
abstract: One of the hypothesized protective mechanisms of soy against breast cancer involves changes in estrogen metabolism to 2-hydroxy (OH) and 16α-OH estrogens. The current analysis examined the effect of soy foods on the 2:16α-OH E(1) ratio among premenopausal women during a randomized, crossover intervention study; women were stratified by equol producer status, a characteristic thought to enhance the protective effects of soy isoflavones. The study consisted of a high-soy diet with 2 soy food servings/day and a low-soy diet with <3 servings of soy/wk for 6 mo each; estrogen metabolites were measured in 3 overnight urines (baseline and at the end of the low- and high-soy diet) using gas chromatography mass spectrometry for the 82 women who completed the study. Urinary isoflavonoids were assessed by liquid chromatography mass spectrometry. When applying mixed models, the 2:16α-OH E(1) ratio increased (P = 0.05) because of a nonsignificant decrease in 16α-OH E(1) (P = 0.21) at the end of the high-soy diet. Similar nonsignificant increases in the 2:16α-OH E(1) ratio were observed in equol producers (P = 0.13) and nonproducers (P = 0.23). These findings suggest a beneficial influence of soy foods on estrogen metabolism regardless of equol producer status.
authors.affiliation: University of Hawaii Cancer Center, Honolulu, Hawaii 96813, USA.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Morimoto
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Conroy
authors.forename: Ian S
authors.initials: IS
authors.lastname: Pagano
authors.forename: Marissa
authors.initials: M
authors.lastname: Isaki
authors.forename: Adrian A
authors.initials: AA
authors.lastname: Franke
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Nordt
authors.forename: Gertraud
authors.initials: G
authors.lastname: Maskarinec
mesh_terms: D000328:Adult; D002681:China / Q000208:ethnology; D018592:Cross-Over Studies; D004032:Diet; D060754:Equol / Q000096:biosynthesis; D004967:Estrogens / Q000652:urine*; D005006:Ethnicity; D005260:Female; D005419:Flavonoids / Q000652:urine; D006254:Hawaii; D006801:Humans; D006894:Hydroxyestrones / Q000652:urine; D007529:Isoflavones / Q000008:administration & dosage; D007564:Japan / Q000208:ethnology; D007723:Korea / Q000208:ethnology; D008875:Middle Aged; D010679:Philippines / Q000208:ethnology; D017697:Premenopause; D045730:Soy Foods; D044465:White People
chemical_list: D004967:Estrogens; D005419:Flavonoids; D006894:Hydroxyestrones; D007529:Isoflavones; C026702:16-hydroxyestrone; D060754:Equol; C024980:2-hydroxyestrone