title: Validating polyphenol intake estimates from a food-frequency questionnaire by using repeated 24-h dietary recalls and a unique method-of-triads approach with 2 biomarkers.
abstract: Background:The assessment of polyphenol intake in free-living subjects is challenging, mostly because of the difficulty in accurately measuring phenolic content and the wide presence of phenolics in foods.Objective:The aims of this study were to evaluate the validity of polyphenol intake estimated from food-frequency questionnaires (FFQs) by using the mean of 6 measurements of a 24-h dietary recall (24-HR) as a reference and to apply a unique method-of-triads approach to assess validity coefficients (VCs) between latent "true" dietary estimates, total urinary polyphenol (TUP) excretion, and a surrogate biomarker (plasma carotenoids).Design:Dietary intake data from 899 adults of the Adventist Health Study 2 (AHS-2; 43% blacks and 67% women) were obtained. Pearson correlation coefficients (r), corrected for attenuation from within-person variation in the recalls, were calculated between 24-HRs and FFQs and between 24-HRs and TUPs. VCs and 95% CIs between true intake and polyphenol intakes from FFQs, 24-HRs, and the biomarkers TUPs and plasma carotenoids were calculated.Results:Mean ± SD polyphenol intakes were 717 ± 646 mg/d from FFQs and 402 ± 345 mg/d from 24-HRs. The total polyphenol intake from 24-HRs was correlated with FFQs in crude (r= 0.51,P< 0.001) and deattenuated (r =0.63; 95% CI: 0.61, 0.69) models.In the triad model, the VC between the FFQs and theoretical true intake was 0.46 (95% CI: 0.20, 0.93) and between 24-HRs and true intake was 0.61 (95% CI: 0.38, 1.00).Conclusions:The AHS-2 FFQ is a reasonable indicator of total polyphenol intake in the AHS-2 cohort. Urinary polyphenol excretion is limited by genetic variance, metabolism, and bioavailability and should be used in addition to rather than as a replacement for dietary intake assessment.
authors.affiliation: School of Public Health, Loma Linda University, Loma Linda, CA.
authors.forename: Nasira M
authors.initials: NM
authors.lastname: Burkholder-Cooley
authors.affiliation: School of Public Health, Loma Linda University, Loma Linda, CA.
authors.forename: Sujatha S
authors.identifier: 0000-0001-6367-4406
authors.initials: SS
authors.lastname: Rajaram
authors.affiliation: School of Public Health, Loma Linda University, Loma Linda, CA.
authors.forename: Ella H
authors.identifier: 0000-0002-9137-8433
authors.initials: EH
authors.lastname: Haddad
authors.affiliation: School of Public Health, Loma Linda University, Loma Linda, CA.
authors.forename: Keiji
authors.identifier: 0000-0001-6268-9032
authors.initials: K
authors.lastname: Oda
authors.affiliation: School of Public Health, Loma Linda University, Loma Linda, CA.
authors.forename: Gary E
authors.identifier: 0000-0002-5577-3524
authors.initials: GE
authors.lastname: Fraser
authors.affiliation: School of Public Health, Loma Linda University, Loma Linda, CA kjaceldo@llu.edu.
authors.forename: Karen
authors.identifier: 0000-0001-7182-3475
authors.initials: K
authors.lastname: Jaceldo-Siegl
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood / Q000652:urine; D002338:Carotenoids / Q000097:blood; D004032:Diet; D015930:Diet Records; D004034:Diet Surveys; D002149:Energy Intake; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D059808:Polyphenols / Q000008:administration & dosage* / Q000652:urine; D012016:Reference Values; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires / Q000592:standards*
chemical_list: D015415:Biomarkers; D059808:Polyphenols; D002338:Carotenoids
keywords: Adventist Health Study 2; method of triads; phytochemicals; polyphenols; urinary polyphenols