Development of data-based semi-quantitative food frequency questionnaire for dietary studies in middle-aged Japanese

Background: We designed a data-based semi-quantitative food frequency quest ionnaire to clarify the relationship between food intake and lifestyle-rela ted diseases among middle-aged Japanese. Methods: A total of 351 middle-aged individuals were recruited to a one-day weighed diet record survey in 1994. In all, 586 foods were consumed. Intak e of 31 nutrients including energy, protein, fat, carbohydrate, vitamins, m inerals and dietary fiber by food was computed by multiplying the weight of food consumed by its nutrient content. First, 252 foods with up to 90 cumu lative % contribution to nutrient intake were selected. Of these, foods hav ing apparently the same/similar nutrient content were combined into 206 foo ds by research dietitians. Next, 183 foods with up to 0.90 cumulative multi ple regression coefficient and 90 cumulative % contribution were chosen. At this stage an additional food grouping was made. Results: Finally, 102 foods/recipes were included in the questionnaire: ric e (2 items), bread and noodles (11), eggs, milk and dairy products (10), so ybean, soybean products and other beans (7), meat including beef, pork and chicken (12), fish (5), other fish, shellfish and fish products (10), green -yellow vegetables (8), other vegetables and mushrooms (7), edible roots (2 ), seaweeds (3), seeds (2), fruits (8), beverages (7) and confectioneries ( 8). The frequencies were classified into eight categories. Portion size was calculated for the respective foods largely from the one-day weighed diet record. Conclusions: The developed semi-quantitative food frequency questionnaire s ubstantially covered the intake of 31 nutrients and may be competent to ran k middle-aged Japanese efficiently.