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.

Although many epidemiological studies have examined the association of dietary glycaemic index (GI) and glycaemic load (GL) with health outcomes, information on the reproducibility and relative validity of these variables estimated from dietary questionnaires is extremely limited. We examined the reproducibility and relative validity of dietary GI and GL assessed with a self-administered diet-history questionnaire (DHQ) in adult Japanese. A total of ninety-two Japanese women and ninety-two Japanese men aged 31-76 years completed the DHQ (assessing diet during the preceding month) and 4 d dietary records (DR) in each season over a 1-year period (DHQ1-4 and DR1 -4, respectively) and the DHQ at 1 year after completing DHQ1 (DHQ5). We used intraclass correlations between DHQ1 and DHQ5 to assess reproducibility, and Pearson correlations between the mean of DR1-4 and mean of DHQ1 -4 and between the mean of DR1 -4 and DHQ1 to assess relative validity. Reproducibility correlations for dietary GI and GL were 0·57 and 0·69 among women and 0·65 and 0·58 among men, respectively. Validity correlations for dietary GI and GL assessed by DHQ1 -4 were 0·72 and 0·66 among women and 0·65 and 0·71 among men, respectively. Corresponding correlations for DHQ1 were 0·53 and 0·58 among women and 0·57 and 0·60 among men, respectively. White rice was the major contributor to GI and GL in both methods (49-64 %). These data indicate reasonable reproducibility and relative validity of dietary GI and GL assessed by a DHQ for Japanese adults, whose dietary GI and GL are primarily determined by the GI of white rice.Dietary glycaemic index: Diet-history questionnaires: Relative validity: Japanese Glycaemic index (GI) is defined as the incremental area under the blood glucose response curve of available carbohydrate in a food expressed as a percentage of the response to available carbohydrate in a reference food (usually glucose, white bread or white rice), and thus represents the quality of carbohydrate 1 . Glycaemic load (GL) is the product of the GI and the available carbohydrate content of the food, and thus represents both the quality and the quantity of carbohydrate 2 . The recent publication of accumulated GI and GL values for about 750 individual food items 3 has made possible the incorporation of GI and GL into questionnaire-based assessments of usual diet, and hence to calculate dietary GI and GL. To date, numerous dietary assessment questionnaires have been used in epidemiological studies to investigate associations between dietary GI and GL and various health outcomes, including type 2 diabetes 2,4 , CVD 5 , several cancers 6 and metabolic risk factors 7 -11 .Although the dietary questionnaires used in these studies have been validated for a wide range of nutrients and foods, information on the reproducibility and relative validity of dietary GI and GL derived from dietary questionnaires is extremely limited. Very recently, a Swedish study examined this issue using 2 £ 7 d dietary records (DR) as a gold standard 12 . However, the su...

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Objective: Although dietary pattern approaches derived from dietary assessment questionnaires are widely used, only a few studies in Western countries have reported the validity of this approach. We examined the relative validity of dietary patterns derived from a self-administered diet history questionnaire (DHQ) among Japanese adults. Design: The DHQ, assessing diet during the preceding month, and 4 d dietary records (DR) were collected in each season over one year. To derive dietary patterns, 145 food items in the DHQ and 1259 in the DR were classified into thirtythree predefined food groups, and entered into a factor analysis. Setting: Three areas in Japan; Osaka (urban), Nagano (rural inland) and Tottori (rural coastal). Subjects: A total of ninety-two Japanese women and ninety-two Japanese men aged 31-76 years. Results: We identified three dietary patterns ('healthy', 'Western' and 'Japanese traditional') in women and two ('healthy' and 'Western') in men, which showed a relatively similar direction and magnitude of factor loadings of food groups across the first and mean of four DHQ (DHQ1 and mDHQ, respectively) and 16 d DR. The Pearson correlation coefficients between DHQ1 and 16 d DR for the healthy, Western and Japanese traditional patterns in women were 0?57, 0?36 and 0?44, and for the healthy and Western patterns in men were 0?62 and 0?56, respectively. When mDHQ was examined, the correlation coefficients improved for women (0?45-0?69). Conclusions: Dietary patterns derived from the DHQ could be used for epidemiological studies as surrogates of those derived from DR.