Validity and Reproducibility of a Food Frequency Questionnaire for Dietary Assessment in Japanese People.

A 76-item food frequency questionnaire (FFQ) was developed to investigate nutritional epidemiology in urban residents in Japan. The authors prepared two food models-a life-size three-dimensional model and a life-size two-dimensional photograph-to assess the FFQ portion size. The validity of the FFQ was verified using the two food models by comparing them with 16-d weighted dietary records (WDRs). Validation was conducted by comparing the FFQ1 findings with those obtained with the WDR, which is regarded as the gold standard, and reproducibility was verified by comparing the findings from FFQ2 and FFQ1. After completion of the WDR, the participants were randomized into two groups. In one group, the FFQ was conducted using life-size three-dimensional models (3D-FFQ) to estimate the portion size. In the other group, the FFQ was administered using life-size photo collection (2D-FFQ). Regarding validity, the median values (range) of Pearson's correlation coefficients for the energy and nutrient intake of the 32 items by the WDR and FFQ1 were r=0.53 (0.30-0.68) in the 3D-FFQ and r=0.57 (0.33-0.87) in the 2D-FFQ. When FFQs with 2D or 3D food models and two different portion sizes were compared with regard to the intake of certain food groups, energy, and nutrients, both the 2D-FFQ and 3D-FFQ provided good correlation coefficients with the WDR.

Applying a meal coding system to 16-d weighed dietary record data in the Japanese context: towards the development of simple meal-based dietary assessment tools.

Data on the combination of foods consumed simultaneously at specific eating occasions are scarce, primarily due to a lack of assessment tools. We applied a recently developed meal coding system to multiple-day dietary intake data for assessing its ability to estimate food and nutrient intakes and characterise meal-based dietary patterns in the Japanese context. A total of 242 Japanese adults completed sixteen non-consecutive-day weighed dietary records, including 14 734 eating occasions (3788 breakfasts, 3823 lunches, 3856 dinners and 3267 snacks). Common food group combinations were identified by meal type to identify a range of generic meals. Dietary intake was calculated on the basis of not only the standard food composition database but also the substituted generic meal database. In total, eighty generic meals (twenty-three breakfasts, twenty-one lunches, twenty-four dinners and twelve snacks) were identified. The Spearman correlation coefficients between food group intakes calculated based on the standard food composition database and the substituted generic meal database ranged from 0·26 to 0·85 (median 0·69). The corresponding correlations for nutrient intakes ranged from 0·17 to 0·82 (median 0·61). A total of eleven meal patterns were established using principal components analysis, and these accounted for 39·1 % of total meal variance. Considerable variation in patterns was seen in meal type inclusion and choice of staple foods (bread, rice and noodles) and drinks, and also in meal constituents. In conclusion, this study demonstrated the usefulness of a meal coding system for assessing habitual diet, providing a scientific basis towards the development of simple meal-based dietary assessment tools.

Validation study of a self-administered diet history questionnaire for estimating amino acid intake among Japanese adults.

BACKGROUND AND OBJECTIVES: Despite growing interest in the association between dietary amino acid intake and optimal health, validated dietary questionnaires that can estimate amino acid intake have been scarce. We examined the validity of amino acid intakes estimated using a self-administered diet history questionnaire (DHQ) comparing with 16-day semi-weighed dietary records (DR). METHODS AND STUDY DESIGN: A total of 184 Japanese men and women completed a four-day DR and a DHQ four times, once in each season. Dietary amino acid intakes were estimated as crude, energy-adjusted, and percentage of total protein intake (% protein) using an amino acid database of Japanese foods. The validity of dietary amino acid intake estimated by the first-time DHQ was examined using the mean of 16 days' DRs as reference. RESULTS: Mean intakes of almost all amino acids estimated by DHQ were significantly lower than those estimated by the DR for energy-adjusted values in both sexes. Although mean amino acid intakes estimated by DHQ were significantly higher than those estimated by the DR for % protein value, the differences between the DR and DHQ were slight (-0.04 to 0.39% protein for men, -0.05 to 0.37% protein for women). Pearson correlation coefficients between DHQ and the DR showed reasonable ranking ability in % protein values for men (interquartile range (Q1-Q3): 0.31-0.47) and energy-adjusted values for women (interquartile range (Q1-Q3): 0.40-0.45). CONCLUSION: DHQ showed acceptable ability to estimate mean amino acid intake and to rank individuals in a population according to their amino acid intake for using in large-scale epidemiological studies.

Estimation of habitual iodine intake in Japanese adults using 16 d diet records over four seasons with a newly developed food composition database for iodine.

Although habitual seaweed consumption in Japan would suggest that iodine intake in Japanese is exceptionally high, intake data from diet records are limited. In the present study, we developed a composition database of iodine and estimated the habitual intake of iodine among Japanese adults. Missing values for iodine content in the existing composition table were imputed based on established criteria. 16 d diet records (4 d over four seasons) from adults (120 women aged 30-69 years and 120 men aged 30-76 years) living in Japan were collected, and iodine intake was estimated. Habitual intake was estimated with the Best-power method. Totally, 995 food items were imputed. The distribution of iodine intake in 24 h was highly skewed, and approximately 55 % of 24 h values were < 300 µg/d. The median iodine intake in 24 h was 229 µg/d for women and 273 µg/d for men. All subjects consumed iodine-rich foods (kelp or soup stock) on one or more days of the sixteen survey days. The mean (median) habitual iodine intake was 1414 (857) µg/d for women and 1572 (1031) µg/d for men. Older participants had higher intake than younger participants. The major contributors to iodine intake were kelp (60 %) and soup stock (30 %). Habitual iodine intake among Japanese was sufficient or higher than the tolerable upper intake level, particularly in older generations. The association between high iodine intake as that observed in the present study and thyroid disease requires further study.

Designing optimal food intake patterns to achieve nutritional goals for Japanese adults through the use of linear programming optimization models.

BACKGROUND: Simultaneous dietary achievement of a full set of nutritional recommendations is difficult. Diet optimization model using linear programming is a useful mathematical means of translating nutrient-based recommendations into realistic nutritionally-optimal food combinations incorporating local and culture-specific foods. We used this approach to explore optimal food intake patterns that meet the nutrient recommendations of the Dietary Reference Intakes (DRIs) while incorporating typical Japanese food selections. METHODS: As observed intake values, we used the food and nutrient intake data of 92 women aged 31-69 years and 82 men aged 32-69 years living in three regions of Japan. Dietary data were collected with semi-weighed dietary record on four non-consecutive days in each season of the year (16 days total). The linear programming models were constructed to minimize the differences between observed and optimized food intake patterns while also meeting the DRIs for a set of 28 nutrients, setting energy equal to estimated requirements, and not exceeding typical quantities of each food consumed by each age (30-49 or 50-69 years) and gender group. RESULTS: We successfully developed mathematically optimized food intake patterns that met the DRIs for all 28 nutrients studied in each sex and age group. Achieving nutritional goals required minor modifications of existing diets in older groups, particularly women, while major modifications were required to increase intake of fruit and vegetables in younger groups of both sexes. Across all sex and age groups, optimized food intake patterns demanded greatly increased intake of whole grains and reduced-fat dairy products in place of intake of refined grains and full-fat dairy products. Salt intake goals were the most difficult to achieve, requiring marked reduction of salt-containing seasoning (65-80%) in all sex and age groups. CONCLUSION: Using a linear programming model, we identified optimal food intake patterns providing practical food choices and meeting nutritional recommendations for Japanese populations. Dietary modifications from current eating habits required to fulfil nutritional goals differed by age: more marked increases in food volume were required in younger groups.

Higher proportion of total and fat energy intake during the morning may reduce absolute intake of energy within the day. An observational study in free-living Japanese adults.

BACKGROUND: Although the distribution of energy intake throughout the day appears to impact overall daily energy intake, little is known about the ad libitum distribution of energy intake. OBJECTIVE: Our aim was to investigate associations between the distribution of energy intake during the day and subsequent or overall energy intake, and food choice in free-living adults. DESIGN: A total of 119 women and 116 men completed 16-day semi-weighed dietary records. The longitudinal dietary intake data for each participant were analyzed using a mixed model to examine the effect of energy intake at various times of day on subsequent or overall energy intake. RESULTS: Mean proportion of total energy intake in the morning (4:00 a.m.-10:29 a.m.), afternoon (10:30 a.m.-4:59 p.m.) and evening (5:00 p.m.-3:59 a.m.) meal was 22.6%, 33.8% and 43.6% in men, and 24.7%, 36.5%, 38.8% in women, respectively. Proportion of energy intake (%) in the morning meal was significantly and negatively associated with energy intake (kcal) in the subsequent afternoon and evening meals, and consequently in the whole day in both sexes. This significant and negative association was also observed for proportion of energy intake (%) of fat, but not of carbohydrate or protein, in both sexes. Proportion of energy intake (%) in the morning meal was negatively associated with overall energy intake (kcal) from the group of meats, fish, and eggs in both sexes, and from the group of confectioneries and soft drinks in women. CONCLUSIONS: More energy in the morning meal may reduce energy intake, especially that from fat, in the subsequent meals, and consequently in the whole day.

Estimation of intakes of copper, zinc, and manganese in Japanese adults using 16-day semi-weighed diet records.

Data for the intake of copper, zinc, and manganese in Japanese populations obtained by detailed diet assessment methods and the most recent version of the food composition database in Japan are scarce. Moreover, data on food sources which contribute to the intake of these nutrients in Asian countries, including Japan, are not available. Here, we estimated copper, zinc, and manganese intake and elucidated major food sources of these nutrients in a Japanese population. We collected 16-day diet records from 225 adults aged 30 to 69 years living in 4 areas of Japan. Intakes of copper, zinc, and manganese were estimated using the 16-day diet records and the latest version of the Food Composition Tables in Japan. Mean intakes of copper, zinc, and manganese were 1.2 mg/day, 8.2 mg/day, and 4.9 mg/day for women and 1.4 mg/day, 10.1 mg/day, and 5.1 mg/day for men, respectively. White rice was the largest contributor to the intake of copper, zinc, and manganese, accounting for approximately 20%-30% of the total intake of each.

Effect of seasonality on the estimated mean value of nutrients and ranking ability of a self-administered diet history questionnaire.

BACKGROUND: We examined the effect of seasonality on the validity (ability to estimate the mean intake of a group and ranking ability) of nutrient intakes estimated with a comprehensive self-administered diet history questionnaire (DHQ) developed for the assessment of Japanese diets during the preceding one month, using semi-weighed dietary records (DRs) as a reference method. METHODS: This study was conducted in three areas in Japan (Osaka, Nagano, and Tottori). The study population included 92 Japanese men aged 32-76 years and 92 Japanese women aged 31-69 years (30 from Osaka, 31 from Nagano, and 31 from Tottori for each sex). A DHQ and a four-day DR were completed four times at 3-month intervals, once per season. The effect of seasonality was examined by the level of agreement among seasons using mean nutrient intake and correlation coefficients. RESULTS: Significant differences in estimated energy-adjusted intakes of 42 selected nutrients between the average of DRs administered 16 times throughout a year and that of the DHQ administered four times in each season (fall, winter, spring, and summer) were observed for 30, 29, 30, and 31 nutrients for men and 21, 28, 30, and 31 nutrients for women, respectively. Pearson correlation coefficients between the DRs and the DHQs for energy-adjusted intakes of the 42 nutrients showed significant inter-season differences in 11 nutrients for men and 13 nutrients for women. Particularly, correlation coefficients of fat, monounsaturated fat, polyunsaturated fat, n-6 polyunsaturated fat, α-linolenic acid, and cholesterol in spring and cryptoxanthin in summer for men, and fat, saturated fat, and monounsaturated fat in spring and summer and thiamin and iron in summer for women were markedly altered by seasonality. CONCLUSIONS: Mean nutrient intake estimated by the DHQ varied by season, indicating that any consideration of nutrient intake estimated by the DHQ as a yearly average intake may be problematic. In contrast, the effect of seasonality on the ranking ability of the DHQ was relatively small, and thus the use of a DHQ to rank individuals by nutrient intake is acceptable for epidemiological studies, regardless of season.

Within- and between-individual variation in energy and nutrient intake in Japanese adults: effect of age and sex differences on group size and number of records required for adequate dietary assessment.

BACKGROUND: Information on within- and between-individual variation in energy and nutrient intake is critical for precisely estimating usual dietary intake; however, data from Japanese populations are limited. METHODS: We used dietary records to examine within- and between-individual variation by age and sex in the intake of energy and 31 selected nutrients among Japanese adults. We also calculated the group size required to estimate mean intake for a group and number of days required both to rank individuals within a group and to assess an individual's usual intake, all with appropriate arbitrary precision. A group of Japanese women (younger: 30-49 years, n = 58; older: 50-69 years, n = 63) and men (younger: 30-49 years, n = 54; older: 50-76 years, n = 67) completed dietary records for 4 nonconsecutive days in each season (16 days in total). RESULTS: Coefficients of within-individual variation and between-individual variation were generally larger in the younger group than in the older group and in men as compared with women. The group size required to estimate a group's mean intake, and number of days required to assess an individual's usual intake, were generally larger for the younger group and for men. In general, a longer period was required to rank women and older adults. CONCLUSIONS: In a group of Japanese adults, coefficients of within-individual variation and between-individual variation, which were used to estimate the group size and number of records required for adequate dietary assessment, differed by age, sex, and nutrient.

Both comprehensive and brief self-administered diet history questionnaires satisfactorily rank nutrient intakes in Japanese adults.

BACKGROUND: A 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. METHODS: Ninety-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). RESULTS: No 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. CONCLUSIONS: The 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.

Comparison of relative validity of food group intakes estimated by comprehensive and brief-type self-administered diet history questionnaires against 16 d dietary records in Japanese adults.

OBJECTIVE: To compare the relative validity of food group intakes derived from a comprehensive self-administered diet history questionnaire (DHQ) and a brief-type DHQ (BDHQ) developed for the assessment of Japanese diets during the previous month using semi-weighed dietary records (DR) as a reference method. DESIGN: Between November 2002 and September 2003, a 4 d DR (covering four non-consecutive days), a DHQ (150-item semi-quantitative questionnaire) and a BDHQ (fifty-eight-item fixed-portion-type questionnaire) were completed four times (once per season) at 3-month intervals. SETTING: Three areas in Japan: Osaka, Nagano and Tottori. SUBJECTS: Ninety-two Japanese women aged 31-69 years and ninety-two Japanese men aged 32-76 years. RESULTS: Median food group intakes were estimated well for approximately half of the food groups. No statistically significant differences were noted between a 16 d DR and the first DHQ (DHQ1) or between the DR and the first BDHQ (BDHQ1) in fifteen (44 %) and fifteen (52 %) food items for women and in fourteen (41 %) and sixteen (55 %) food items for men, respectively, indicating that both questionnaires estimated median values reasonably well. Median Spearman's correlation coefficients with the DR were 0·43 (range: -0·09 to 0·77) for DHQ1 and 0·44 (range: 0·14 to 0·82) for BDHQ1 in women, with respective values of 0·44 (range: 0·08 to 0·87) and 0·48 (range: 0·22 to 0·83) in men, indicating reasonable ranking ability. Similar results were observed for mean values of the four DHQ and BDHQ. CONCLUSIONS: In terms of food intake estimates, both the DHQ and the BDHQ showed reasonable validity.

Estimation of caffeine intake in Japanese adults using 16 d weighed diet records based on a food composition database newly developed for Japanese populations.

OBJECTIVE: Previous studies in Western populations have linked caffeine intake with health status. While detailed dietary assessment studies in these populations have shown that the main contributors to caffeine intake are coffee and tea, the wide consumption of Japanese and Chinese teas in Japan suggests that sources of intake in Japan may differ from those in Western populations. Among these teas, moreover, caffeine content varies widely among the different forms consumed (brewed, canned or bottled), suggesting the need for detailed dietary assessment in estimating intake in Japanese populations. Here, because a caffeine composition database or data obtained from detailed dietary assessment have not been available, we developed a database for caffeine content in Japanese foods and beverages, and then used it to estimate intake in a Japanese population. DESIGN: The caffeine food composition database was developed using analytic values from the literature, 16 d weighed diet records were collected, and caffeine intake was estimated from the 16 d weighed diet records. SETTING: Four areas in Japan, Osaka (Osaka City), Okinawa (Ginowan City), Nagano (Matsumoto City) and Tottori (Kurayoshi City), between November 2002 and September 2003. SUBJECTS: Two hundred and thirty Japanese adults aged 30-69 years. RESULTS: Mean caffeine intake was 256.2 mg/d for women and 268.3 mg/d for men. The major contributors to intake were Japanese and Chinese teas and coffee (47 % each). Caffeine intake above 400 mg/d, suggested in reviews to possibly have negative health effects, was seen in 11 % of women and 15 % of men. CONCLUSIONS: In this Japanese population, caffeine intake was comparable to the estimated values reported in Western populations.

Relative validity of dietary patterns derived from a self-administered diet history questionnaire using factor analysis among Japanese adults.

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 thirty-three 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.

Estimation of trans fatty acid intake in Japanese adults using 16-day diet records based on a food composition database developed for the Japanese population.

BACKGROUND: The Standard Tables of Food Composition in Japan do not include information on trans fatty acids. Previous studies estimating trans fatty acid intake among Japanese have limitations regarding the databases utilized and diet assessment methodologies. We developed a comprehensive database of trans fatty acid food composition, and used this database to estimate intake among a Japanese population. METHODS: The database was developed using analytic values from the literature and nutrient analysis software encompassing foods in the US, as well as values estimated from recipes or nutrient compositions. We collected 16-day diet records from 225 adults aged 30 to 69 years living in 4 areas of Japan. Trans fatty acid intake was estimated based on the database and the 16-day diet records. RESULTS: Mean total fat and trans fatty acid intake was 56.9 g/day (27.7% total energy) and 1.7 g/day (0.8% total energy), respectively, for women and 66.8 g/day (25.5% total energy) and 1.7 g/day (0.7% total energy) for men. Trans fatty acid intake accounted for greater than 1% of total energy intake, which is the maximum recommended according to the World Health Organization, in 24.4% of women and 5.7% of men, and was particularly high among women living in urban areas and those aged 30-49 years. The largest contributors to trans fatty acid intake were confectionaries in women and fats and oils in men. CONCLUSIONS: Although mean trans fatty acid intake was below the maximum recommended intake of the World Health Organization, intake among subgroups was of concern. Further public health efforts to reduce trans fatty acid intake should be encouraged.

Reproducibility and relative validity of dietary glycaemic index and load assessed with a self-administered diet-history questionnaire in Japanese adults.

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.

Comparability of weighed dietary records and a self-administered diet history questionnaire for estimating monetary cost of dietary energy.

An increasing number of studies have estimated monetary diet cost using various dietary assessment methods, based on databases on retail food prices, for investigating its association with dietary intake and health outcomes. However, information regarding the comparability of monetary diet cost across dietary assessment methods is absolutely lacking. This study compared monetary cost of dietary energy estimated from weighed dietary records (DRs) with that estimated from a self-administered diet history questionnaire (DHQ). The subjects were 92 Japanese women aged 31-69 years and 92 Japanese men aged 32-76 years. The DHQ (assessing diet during the preceding month) and 4-day DRs (one weekend day and three weekdays) were completed in each season over a 1-year period (DHQs1-4 and DRs1-4, respectively). An additional DHQ was completed at one year after completing DHQ1 (DHQ5). Monetary cost of dietary energy (Japanese yen/4184 kJ) was calculated using food intake information derived from each dietary assessment method, based on retail food prices. Pearson correlation between the mean of DRs1-4 and mean of DHQs1-4 was 0.64 for women and 0.69 for men. Pearson correlation between the mean of DRs1-4 and DHQ1 was 0.60 for women and 0.52 for men, while intraclass correlation between DHQ1 and DHQ5 was 0.64 for women and 0.51 for men. These data indicate reasonable comparability of monetary cost of dietary energy across DR and a DHQ as well as usefulness of a single administration of the DHQ for estimating monetary cost of dietary energy.

The influence of age and body mass index on relative accuracy of energy intake among Japanese adults.

OBJECTIVE: To examine relationships between the ratio of energy intake to basal metabolic rate (EI/BMR) and age and body mass index (BMI) among Japanese adults. DESIGN: Energy intake was assessed by 4-day semi-weighed diet records in each of four seasons (16 days in total). The EI/BMR ratio was calculated from reported energy intake and estimated basal metabolic rate as an indicator of reporting accuracy. SETTING: Residents in three areas in Japan, namely Osaka (urban), Nagano (rural inland) and Tottori (rural coastal). SUBJECTS: One hundred and eighty-three healthy Japanese men and women aged > or =30 years. RESULTS: The oldest age group (> or =60 years) had higher EI/BMR values than the youngest age group (30-39 years) in both sexes (1.74 vs. 1.37 for men; 1.65 vs. 1.43 for women). In multiple regression analyses, age correlated positively (partial correlation coefficient, beta = 0.012, P < 0.001 for men; beta = 0.011, P < 0.001 for women) and BMI correlated negatively (beta = -0.031, P < 0.001 for men; beta = -0.025, P < 0.01 for women) with EI/BMR. CONCLUSION: Age and BMI may influence the relative accuracy of energy intake among Japanese adults.