It is well known that the leading causes of death are now chronic diseases such as cancer, cerebrovascular problems and heart disease in developed countries, including Japan. 1 They are related to daily lifestyle, including dietary habit, alcohol drinking, smoking, physical exercise, and factors for stress. Because dietary habit, in particular, appears to play a major role in their pathogenesis, batteries of tests to assess intake of foods/nutrients, including fats/fatty acids, antioxidants and dietary fibers, are needed for epidemiologic studies.There are several tools available, including diet records (DRs)/weighed diet records (WDRs), 24-hour recall, food frequency questionnaires (FFQs), and duplicate methods.
Calculation of intake of nutrientsWe computed the average daily consumption of energy and selected nutrients using information from the FFQ and lifestyle questionnaire, including consumption of alcohol. According to the regression analysis, selected nutrients were adopted as dependent parameters and foods/food groups consumed, intake frequency, portion size (in grams) from our database, 5,8 or typical/standard values from the literature, nutrient contents per 100 grams of foods/food groups listed in the respective composition tables or of the model recipes were assumed to be independent variables. [9][10][11][12][13] With the WDRs, we calculated mean daily intakes of selected nutrients by multiplying the consumption of foods/food groups (in grams) and nutrient contents per 100 grams of foods as listed in the composition tables or model recipes.
ValidationFirst, we compared mean daily intakes of energy and 26 selected nutrients gauged with the FFQ against those with the 3d-WDRs. Differences in means and ratios were computed with the FFQ vs. 3d-WDRs values, and examined by t-test using Excel ® and the SPSS ® -10.0 software package.Second, we calculated crude Pearson's correlation coefficients (CCs), log-transformed Pearson's CCs, log-transformed and energy-adjusted Pearson's CCs, and de-attenuated, log-transformed and energy-adjusted Pearson's CCs between intakes of selected nutrients based on the FFQ and 3d-WDRs. Energy adjustment was executed using regression models. 14 De-attenuated Pearson's CCs were computed by partitioning within-and inter-individual variations by one way of analysis of variance according to the formula described elsewhere. 3, 15-17 Crude Spearman's rank CCs and energy-adjusted Spearman's rank CCs were also calculated. 18,19 Statistical significance was verified with the 95% confidence interval.Third, after categorizing daily intakes of nutrients quantified with the FFQ and 3d-WDRs into quartiles, we computed percentages of exact agreement, agreement within adjacent categories, and disagreement.
Ethical issuesOur study protocol was reviewed and approved by the Internal Review Board at Nagoya City University Graduate School of Medical Sciences. Written informed consent was obtained from each participant.
Profile of study subjectsThe mean ages standard deviations (SDs) (minimum -max...