Reliability and validity of an assessment of usual phytoestrogen consumption (United States)

Pamela L. Horn-Ross, Stephen Barnes, Valerie S. Lee, Christine N. Collins, Peggy Reynolds, Marion M. Lee, Susan L. Stewart, Alison J. Canchola, Landon Wilson, Kenneth Jones

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Objective: To evaluate the reliability and validity of a food-frequency questionnaire (FFQ) and database designed to quantify phytoestrogen consumption. Methods: This study included 195 members of the California Teachers Study (CTS) cohort who, over a 10-month period, completed four 24-h dietary recalls, a pre- and post-study FFQ, and provided two 24-h urine specimens. Participants (n=106) in a parallel study (and 18 women who dropped out of the long-term study) completed a single recall and FFQ, and provided one 24-h urine specimen. Urinary phytoestrogens were determined using liquid chromatography-mass spectrometry. Reliability and validity were evaluated using Shrout-Fleiss intraclass correlations and energy-adjusted deattenuated Pearson correlations, respectively. Results: Correlations reflecting the reproducibility of the FFQ phytoestrogen assessment ranged from 0.67 to 0.81. Validity correlations (FFQ compared to dietary recalls) ranged from 0.67 to 0.79 for the major phytoestrogenic compounds (i.e., daidzein, genistein, and secoisolariciresinol) and 0.43 to 0.54 for the less common compounds. Compared to urinary levels, validity correlations ranged from 0.41 to 0.55 for the isoflavones and 0.16 to 0.21 for total lignans. Conclusion: Our isoflavone assessment is reproducible, valid, and an excellent tool for evaluating the relationship with disease risk in non-Asian populations. Further research is needed before these tools can accurately be used to assess lignan consumption.

Original languageEnglish (US)
Pages (from-to)85-93
Number of pages9
JournalCancer Causes and Control
Issue number1
StatePublished - Feb 2006
Externally publishedYes


  • Dietary assessment
  • Phytoestrogens
  • Reliability
  • Urinary excretion
  • Validity

ASJC Scopus subject areas

  • Oncology
  • Epidemiology
  • Cancer Research


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