Validation of a short food frequency questionnaire specific for iodine in UK females of childbearing age

Combet, E. and Lean, M.E.J. (2014) Validation of a short food frequency questionnaire specific for iodine in UK females of childbearing age. Journal of Human Nutrition and Dietetics, 27(6), pp. 599-605. (doi: 10.1111/jhn.12219)

Abstract

<b>Background</b> Widespread subclinical iodine insufficiency has recently been reported in Europe, based on urinary iodine using World Health Organization/Food and Agriculture Organization criteria, in particular among young women. Although urinary iodine concentration (UIC) is a useful measurement of the iodine status in a population, it does not provide an insight into the habitual iodine intake of this population. This is compounded by the fact that very few iodine-specific food frequency questionnaires (FFQ) have been validated so far. The present study aimed to develop and validate a new, simple, rapid survey tool to assess dietary iodine exposure in females of childbearing age.<p></p> <b>Methods</b> Iodine was measured in a duplicate 24-h urine collection. Iodine intake was measured with duplicate 4-day semi-quantitative food diaries and the FFQ. Correlation, cross-classification and Bland–Altman analyses were used to estimate agreement, bias and the reliability of the method. The triangular (triad) method was used to calculate validity coefficients. <p></p> <b>Results</b> Forty-three women, aged 19–49 years, took part in the validation of the 17-items FFQ. Median (interquartile range) UIC was 74 (47–92) μg L⁻¹, which is indicative of mild iodine insufficiency. The FFQ showed good agreement with food diaries with respect to classifying iodine intake (82% of subjects were classified in the same or adjacent quartile). The FFQ was moderately correlated with the food diaries (r_s = 0.45, P = 0.002) and urinary excretion in μg L⁻¹ (r_s = 0.34, P = 0.025) but not in μg day⁻¹ (P = 0.316). The validity coefficients were 0.69, 0.66 and 0.52 for the food diaries, FFQ and urinary iodine excretion, respectively. <p></p> <b>Conclusions</b> The FFQ provides a rapid and reliable estimate of dietary iodine exposure to identify those population subgroups at risk of iodine deficiency. <p></p>

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Lean, Professor Michael and Combet Aspray, Professor Emilie
• Authors: Combet, E., and Lean, M.E.J.
• College/School: College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing
• Journal Name: Journal of Human Nutrition and Dietetics
• Publisher: Blackwell Publishing
• ISSN: 0952-3871
• ISSN (Online): 1365-277X