Relative validity and reproducibility of a food frequency questionnaire to assess dietary fiber intake in Danish adults

  • Stine Vuholm University of Copenhagen
  • Janne K. Lorenzen University of Copenhagen
  • Mette Kristensen University of Copenhagen
Keywords: Nutrient intake, Dietary fiber, Cereal fiber, Fruit and Vegetable Fiber, Food Frequency Questionnaire, Validation, Reproducibility, Danish population

Abstract

Background: Differences in habitual dietary fiber intake may modify effects of dietary fiber interventions, thus measurement of habitual dietary fiber intake is relevant to apply in intervention studies on fiber-rich foods, and food frequency questionnaire (FFQ) is a commonly used method. Rye bread is the major contributor of dietary fiber in the Danish population, and a nation-specific FFQ is therefore needed.

Objective: The aim of this study was to assess the relative validity and reproducibility of a self-administered quantitative FFQ designed to assess total dietary fiber intake among Danish adults.

Design: In order to assess the relative validity of the FFQ, a total of 125 participants completed both a 7-day weighed dietary recording (DR) and an FFQ consisting of 60 questions. To evaluate the reproducibility of the FFQ, a sub-group of 12 participants subsequently completed an FFQ approximately 6 months later.

Results: Estimates of mean dietary fiber intake were 24.9±9.8 and 28.1±9.4 g/day when applying the FFQ and DR, respectively, where FFQ estimates were ~12% lower (p<0.001). Pearson’s correlation coefficient between the estimated dietary fiber intake of the two methods was r=0.63 (p<0.001), and 62% of the participants were grouped into the same tertile of intake according to the two methods. The estimates of mean dietary intake of first and second FFQ were very similar (22.2±4.0 and 23.3±4.1 g/day, respectively, p=0.42) and showed a correlation of r=0.95 (95% CI 0.83–0.99).

Conclusion: The developed FFQ showed moderate underestimation of dietary fiber intake (g/day), adequate ranking of subjects according to their dietary fiber intake, and good reproducibility. The FFQ is therefore believed to be a valuable tool for epidemiology and screening in human interventions, where intake of dietary fibers is of specific interest.

Keywords: nutrient intake; dietary fiber; cereal fiber; fruit and vegetable fiber; food frequency questionnaire; validation; reproducibility; Danish population

(Published: 4 December 2014)

Citation: Food & Nutrition Research 2014, 58: 24723 - http://dx.doi.org/10.3402/fnr.v58.24723

Responsible Editor: Inge Tetens, Technical University of Denmark, Denmark.

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Author Biographies

Stine Vuholm, University of Copenhagen

Department of Nutrition, Execise and Sports

Faculty of Science

Janne K. Lorenzen, University of Copenhagen

PhD

Department of Nutrition, Execise and Sports

Faculty of Science

Mette Kristensen, University of Copenhagen

PhD, Associate Professor

Department of Nutrition, Execise and Sports

Faculty of Science

Published
2014-12-04
How to Cite
Vuholm, S., Lorenzen, J. K., & Kristensen, M. (2014). Relative validity and reproducibility of a food frequency questionnaire to assess dietary fiber intake in Danish adults. Food & Nutrition Research. https://doi.org/10.3402/fnr.v58.24723
Section
Original Articles