A FOOD FREQUENCY QUESTIONNAIRE TO DETERMINE THE INTAKE OF VITAMIN C: A PILOT VALIDATION STUDY

Abstract

Background and Aims: The aim of this study was to validate a food frequency questionnaire (FFQ) specific to diabetic population wherein the frequency of intake of vitamin C would be examined. Material and Methods: The study is registered with Clinical Trial Registry of India (CTRI) with CTRI number CTRI/2016/03/006764. The FFQ was validated against intakes derived from a 24 Hour Dietary Recall (24 DR). 50 subjects were chosen and a FFQ with 24-hour dietary recall was done. The FFQ had a list of commonly used food items. The vitamin C yield from each food item was pre- calculated. Result and conclusion: Strong correlations between the FFQ and 24 dietary recall were observed for all vitamin C containing food list (Pearson Correlation Coefficient r = 0.997). The p value was significant between the FFQ and 24Hour dietary recall (p = 0.028). Cross classification analysis showed uniform classification of the respondents and there was no misclassification into quartiles. This pilot study showed promising validation evidence for the use of this FFQ, which focuses vitamin C intake in patients with type 2 Diabetes Mellitus, as a screening tool in clinical and research settings.