Food composition and empirical weight methods in predicting nutrient intakes from food frequency questionnaire

PURPOSE: Although the empirical weight (regression-based) method has theoretical advantages over the traditional food composition method in predicting nutrient levels from food frequency questionnaires (FFQs), the empirical assessments have been limited. METHODS: We compared the validity of the two approaches for a 44-item questionnaire used in a population-based prospective study in Japan. Based on four 7-day diet records and questionnaire responses collected from a subsample of the prospective study (94 men and 107 women), we developed a food composition table and stepwise regression models to predict intakes of energy and 14 nutrients from the questionnaire. RESULTS: When we applied the two methods to an independent population (207 men and 166 women) providing a 3-day diet record and responding to a 36-item dietary questionnaire, energy-adjusted and deattenuated correlation coefficients between the questionnaire and the diet records were not higher for the empirical weight method than for the food composition method; the median (range) was 0.22 (0.07-0.57) for men and 0.23 (-0.09-0.62) for women in the former method, and 0.26 (-0.04-0.58) for men and 0.38 (0.18-0.67) for women in the latter method. CONCLUSIONS: We did not find the improved validity of FFQ by empirical weight method in predicting nutrient intakes.