Objective: To compare the relative validity of food group intakes derived from a comprehensive self-administered diet history questionnaire (DHQ) and a brieftype DHQ (BDHQ) developed for the assessment of Japanese diets during the previous month using semi-weighed dietary records (DR) as a reference method. The value of human nutritional studies is largely dependent on the accuracy of the dietary information used. In particular, many epidemiological studies are evaluated by the accuracy of their assessment of an individual's habitual diet. Long-term dietary habits are often assessed using dietary questionnaires (1) ; however, given that food culture and dietary habits vary by country, these need to be developed specifically for each country (2) . In addition, because dietary questionnaires do not necessarily estimate true food intake, their validity needs to be evaluated. The most common way to do this is to assess actual intakes for a limited number of days using dietary records and a 24 h dietary recall (1)(2)(3) . Sasaki et al. (4) developed a comprehensive selfadministered diet history questionnaire (DHQ) that uses both food frequency methodology (consumption frequency and portion size) and diet history methodology (e.g. assessment of cooking methods and staple foods for each meal separately) to estimate the dietary intakes of 150 food and beverage items. This DHQ has been validated using the dietary record (4) , 24 h urine (5) , serum (6) and doubly labelled water (7) methods, and has been used

BackgroundA comprehensive self-administered diet history questionnaire (DHQ: 150-item semi-quantitative questionnaire) and a brief self-administered DHQ (BDHQ: 58-item fixed-portion–type questionnaire) were developed for assessing Japanese diets. We compared the relative validity of nutrient intake derived from DHQ with that from the BDHQ, using semi-weighed 16-day dietary records (DRs) as reference.MethodsNinety-two Japanese women aged 31 to 69 years and 92 Japanese men aged 32 to 76 years completed a 4-nonconsecutive-day DR, a DHQ, and a BDHQ 4 times each (once per season) in 3 areas of Japan (Osaka, Nagano, and Tottori).ResultsNo significant differences were seen in estimates of energy-adjusted intakes of 42 selected nutrients (based on the residual method) between the 16-day DRs and the first DHQ (DHQ1) or between the DR and the first BDHQ (BDHQ1) for 18 (43%) and 14 (33%) nutrients, respectively, among women and for 4 (10%) and 21 (50%) nutrients among men. The median (interquartile range) Pearson correlation coefficients with the DR for energy-adjusted intakes of the 42 nutrients were 0.57 (0.50 to 0.64) for the DHQ1 and 0.54 (0.45 to 0.61) for the BDHQ1 in women; in men, the respective values were 0.50 (0.42 to 0.59) and 0.56 (0.41 to 0.63). Similar results were observed for the means of the 4 DHQs and BDHQs.ConclusionsThe DHQ and BDHQ had satisfactory ranking ability for the energy-adjusted intakes of many nutrients among the present Japanese population, although these instruments were satisfactory in estimating mean values for only a small number of nutrients.

Both dietary GI and GL are independently correlated with several metabolic risk factors in subjects whose dietary GI and GL were primarily determined on the basis of the GI of white rice.