title: Relative and biomarker-based validity of a food frequency questionnaire that measures the intakes of vitamin B(12), folate, iron, and zinc in young women.
abstract: Folate, vitamin B(12), iron, and zinc are particularly important nutrients for women of childbearing age. We tested the hypothesis that an electronic, 235-item, semiquantitative food frequency questionnaire (FFQ) is a valid measure of dietary intake when compared with repeat dietary 24-hour recalls. Biomarkers of folate, vitamin B(12), iron, and zinc were determined because their measurement errors are unrelated to errors in dietary questionnaires. Female adults (N = 256) aged 18 to 35 years completed the FFQ, and a representative subset (n = 53) completed repeat dietary 24-hour recalls. The FFQ estimates (mean ± SD) were 315 ± 132 μg for folate, 3.1 ± 2.1 μg for vitamin B(12), 15.4 ± 5.6 mg for iron, and 15.1 ± 6.4 mg for zinc. The percentage of women classified within the same ±1 quartile for energy intake by the 2 methods was 77.3%. There was moderate agreement between the 2 dietary methods, and no systematic bias was noted for energy, folate, vitamin B(12), and zinc. The deattenuated energy-adjusted correlation coefficients ranged from 0.41 (dietary folate equivalents) to 0.60 (folate). Significant correlations between biomarker and nutrient intakes were found for folate (r = 0.37, P < .01) and vitamin B(12) (r = 0.27, P < .01). The electronic FFQ developed in the present study is a relatively valid tool that was able to adequately assess and rank individuals according to their nutrient intakes.
authors.affiliation: Discipline of Nutrition and Metabolism, School of Molecular Bioscience, University of Sydney, NSW 2006, Australia.
authors.forename: Flavia
authors.initials: F
authors.lastname: Fayet
authors.forename: Victoria
authors.initials: V
authors.lastname: Flood
authors.forename: Peter
authors.initials: P
authors.lastname: Petocz
authors.forename: Samir
authors.initials: S
authors.lastname: Samman
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers; D004034:Diet Surveys; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D006801:Humans; D019266:Iron, Dietary / Q000008:administration & dosage*; D015596:Nutrition Assessment; D011795:Surveys and Questionnaires; D014805:Vitamin B 12 / Q000008:administration & dosage*; D055815:Young Adult; D015032:Zinc / Q000008:administration & dosage*
chemical_list: D015415:Biomarkers; D019266:Iron, Dietary; D005492:Folic Acid; D015032:Zinc; D014805:Vitamin B 12