A Short Questionnaire for Assessment of Dietary Vitamin D Intake

Abstract

Aims: Dietary vitamin D intake is difficult to assess as it is irregular. In Sweden, main sourcesare oily fish, fortified dairy products and margarines. This relative validation study intends to investigate the agreement in dietary vitamin D intake between a short vitamin D questionnaire and a four day food record. Study Design: A cross sectional study design was implemented. Place and Duration of Study: Department of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg. Assessments were conducted between January 2009 and December 2012.  Methodology: Ninety-five female subjects (25-40 years old) performed a short vitamin D questionnaire (VDQ), covering the consumption of four foods with high vitamin D content (oily fish, milk, margarine and yoghurt/sour milk). They also performed a food record for four consecutive days in connection to the VDQ. Results: Median (quartile 1-quartile 3) dietary vitamin D intake was 4.7 (3.6-7.4) µg/day assessed by food record and 3.4 (2.3-4.6) µg/day assessed by VDQ. The dietary intakes of vitamin D correlated significantly between methods (P=.007). The amounts of vitamin D derived from each of the four foods did not differ between methods (P>.05). Conclusion: The short VDQ, including only four foods with high vitamin D content (oily fish, milk, margarine and yoghurt/sour milk), was able to capture the majority of the dietary vitamin D intake reported in food records. This relative validation study shows that the short questionnaire is a useful tool when assessing intake of major sources of dietary vitamin D on a group level.