title: Food frequency questionnaires and overnight urines are valid indicators of daidzein and genistein intake in U.S. women relative to multiple 24-h urine samples.
abstract: Data regarding convenient, valid methods for measuring U.S. isoflavone intake are limited. We evaluated a soy food questionnaire (SFQ), the Willett food frequency questionnaire (FFQ), and overnight urine samples relative to excretion in 24-h urine samples. We also described intake among women in a high-risk program for breast or ovarian cancer. Between April 2002 and June 2003, 451 women aged 30 to 50 yr with a family history of breast or ovarian cancer completed the SFQ and FFQ. Of them, 27 provided four 24-h and overnight urine specimens. In these women, 24-h sample measures were correlated with SFQ estimates of daidzein (Spearman r = .48) and genistein (r = .54) intake, moderately correlated with the Willett FFQ (daidzein r = .38, genistein r = .33), and strongly correlated with overnight urine excretion (daidzein r = .84, genistein r = 0.93). Among all 451 SFQ respondents, mean (median) daidzein and genistein intakes were 2.8 (0.24) and 3.9 (0.30) mg/day. Primary sources of both were soymilk, soy nuts, and tofu. We conclude that targeted soy food questionnaires, comprehensive FFQs, and multiple overnight urines are all reasonable options for assessing isoflavone intake in epidemiologic studies.
authors.affiliation: Division of Population Science, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19130, USA. marilyn.tseng@fccc.edu
authors.forename: Marilyn
authors.initials: M
authors.lastname: Tseng
authors.forename: Temitope
authors.initials: T
authors.lastname: Olufade
authors.forename: Mindy S
authors.initials: MS
authors.lastname: Kurzer
authors.forename: Kristiina
authors.initials: K
authors.lastname: Wahala
authors.forename: Carolyn Y
authors.initials: CY
authors.lastname: Fang
authors.forename: Yvonne T
authors.initials: YT
authors.lastname: van der Schouw
authors.forename: Mary B
authors.initials: MB
authors.lastname: Daly
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000652:urine; D002940:Circadian Rhythm; D015930:Diet Records; D005260:Female; D019833:Genistein / Q000008:administration & dosage* / Q000652:urine*; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage* / Q000652:urine*; D008875:Middle Aged; D015143:Philadelphia; D048789:Phytoestrogens / Q000008:administration & dosage / Q000652:urine; D015203:Reproducibility of Results; D045730:Soy Foods; D011795:Surveys and Questionnaires / Q000592:standards*; D014481:United States
chemical_list: D015415:Biomarkers; D007529:Isoflavones; D048789:Phytoestrogens; C004742:daidzein; D019833:Genistein