• A validated food frequency questionnaire to determine dietary intake of vitamin D

      Watkins, Stephanie; Mushtaq, Sohail; Freeborn, Ellen; University of Chester
      Objective The aim of the present study was to develop and validate a vitamin D food frequency questionnaire (FFQ) for assessment of dietary vitamin D intake in healthy adults in England, UK. Design: The current study assessed the agreement between a four-day food diary (4d-FD) and a new vitamin D FFQ to measure dietary intake of vitamin D. Dietary intake was estimated using Nutritics dietary analysis software and Spearman’s and Bland-Altman tests were utilised to assess correlation and agreement, respectively. Participants also provided a blood sample for plasma analysis of vitamin D concentrations. Setting: Home setting. Participants: Fifty participants were recruited to the study from the University of Chester and vicinity. Results: Results showed a strong correlation between vitamin D intake recorded by the FFQ and the 4d-FD (r = 0.609; P < 0.0001) within 95% limits of agreement. Furthermore, a significant correlation between plasma 25(OH)D concentrations and vitamin D intake measured by the FFQ (r = 0.290, P = 0.041) and the 4d-FD (r = 0.360, P = 0.01) was observed. Conclusion: Our analysis suggests this FFQ is a useful and rapid tool for researchers and health professionals to assess vitamin D dietary intakes in healthy adults in the UK.