Principal component analysis (PCA) has been widely used in nutritional epidemiology to derive dietary patterns. However, although PCA-derived dietary patterns are population-dependent, their reproducibility in different populations is largely unexplored. We aimed to investigate whether major dietary patterns are consistently identified among different populations within a country and, if so, how similar these dietary patterns are. We conducted a systematic review of PCA-derived dietary patterns in Japanese adults using PubMed and Web of Science for English articles and Ichushi-Web and CiNii databases for Japanese articles. We assessed the reproducibility of major dietary patterns using congruence coefficients (CCs), with values ≥0.80 considered to represent fair similarity. From 65 articles (80 studies) included in this review, 285 different dietary patterns were identified. Based on the names of these patterns, major dietary patterns were Western (n = 34), Japanese (n = 12), traditional (n = 10), traditional Japanese (n = 9), healthy (n = 18), and prudent (n = 9) patterns. When assessment was limited to high-quality data (i.e., studies based on a sample size ≥200 and use of a validated dietary assessment questionnaire or multiple-day dietary record), the median CC was low for Western (0.44), traditional (0.59), and traditional Japanese (0.31) patterns. Conversely, the median CC was 0.89 for healthy, 0.86 for prudent, and 0.80 for Japanese patterns; and the proportion of pairs with a CC ≥0.80 was 87.3%, 64.3%, and 50.0%, respectively. Characteristics shared among these 3 dietary patterns included higher intakes of mushrooms, seaweeds, vegetables, potatoes, fruits, pulses, and pickles. In conclusion, this systematic review showed that some of the major dietary patterns are relatively reproducible in different populations within a country, whereas others are not. This highlights the importance of careful interpretation of PCA-derived dietary patterns. Our findings in Japan should be confirmed in different countries and globally. This study was registered at https://www.crd.york.ac.uk/prospero/ as CRD42018087669.

Due to a lack of a food composition database on starch and sugars, we developed a comprehensive database on starch and seven types of sugars in commonly consumed foods (n = 2222) in Japan. Dietary record data of 368 toddlers (aged 18–35 months), 376 preschool children (aged 3–6 years), 915 schoolchildren (aged 8–14 years) and 392 adults (aged 20–69 years) were used. The mean starch intake ranged from 55.6 g/day (female toddlers) to 206.0 g/day (male schoolchildren). Irrespective of age and sex, >50% of starch was provided by rice and grains. The mean total sugar intake ranged from 46.1 g/day (female toddlers) to 68.7 g/day (male schoolchildren). In all age and sex groups, the major contributors of total sugar included sucrose (mean: 18.2–34.0 g/day), glucose (7.8–13.1 g/day), lactose (5.3–13.1 g/day) and fructose (7.6–11.1 g/day). The top food sources were dairy products (toddlers) and confectionaries (other age groups) for total sugar, confectionaries for sucrose, fruits (toddlers) and vegetables (other age groups) for glucose, dairy products for lactose and fruits (toddlers and preschool children) and vegetables (schoolchildren and adults) for fructose. In conclusion, this study clarified the starch and sugar intake in Japan and provides a foundation for future research.

We assessed the adequacy of nutrient intakes of Japanese children aged 3–5 years. Dietary information was collected using a 3-nonconsective-day weighed dietary record among 143 boys and 143 girls. Estimates of usual nutrient intakes from foods and beverages were obtained using the best-power method. The proportions of children with intakes below and above the Japanese Dietary Reference Intakes (DRIs) were estimated. The estimated usual intakes of boys and girls were adequate for most nutrients, given the low proportion (≤2%) of children consuming diets that fell below the Estimated Average Requirement (EAR) or the mean usual intakes higher than the Adequate Intake. However, a high percentage of boys and girls had usual intakes below the EAR for calcium (64% and 54%, respectively), vitamin A (20% and 11%, respectively), thiamin (15% and 41%, respectively), and iron (27% and 10%, respectively). Additionally, 62% of boys and 66% of girls had diets that exceeded the recommended range for total fat (20%–30% energy). Further, 92% for boys and 85% for girls consumed diets that exceeded the recommended limit for sodium (4.0 and 4.5 g NaCl equivalent/day, respectively). In conclusion, the estimated usual intakes were adequate for most nutrients in this sample of 3–5-year-old Japanese children.

BackgroundThe lack of comprehensive food composition databases for sugar contents in Japanese foods has led to the lack of nutritional epidemiologic studies on sugar intake in Japanese population. This cross-sectional study aimed to investigate the association of free sugar intake estimated using a newly developed food composition database with the characteristics and lifestyles of Japanese children aged 3–6 years.MethodsThe food composition database contained information on sugars in 2,222 commonly consumed Japanese foods. Using this database, we estimated the sugar (total, added, and free sugars) intakes derived from a 3-day weighed dietary record of 166 boys and 166 girls aged 3–6 years living in 24 prefectures in Japan.ResultsThe mean free sugar intake was 26.8 g/d (standard deviation [SD], 12.3 g/d), while the mean value for energy intake was 7.8% (SD, 3.2%). The prevalence of excessive free sugar intake (≥10% of energy intake) was 21.7%. Among the characteristics and lifestyles examined, screen time was most strongly associated with the prevalence of excessive free sugar intake: multivariate adjusted odds ratios for screen time <0.5, ≥0.5 to <1, and ≥1 h/d were 1.0 (reference), 3.81 (95% confidence interval, 1.04–13.98), and 4.36 (95% confidence interval, 1.16–16.35), respectively. Additionally, younger age, shorter sleep, and mothers with office work and service and sales jobs (compared with those with professional and managerial jobs) were significantly associated with a higher prevalence of excessive free sugar intake.ConclusionsThis study showed the sugar intake of Japanese children aged 3–6 years is positively associated with screen time.

Objective: This cross-sectional study evaluated the dietary characteristics of snacks, the contribution of snacks to daily nutrient intake and the association of energy intake (EI) from snacks with the prevalence of nutritional inadequacy in Japanese nursery school children. Design: Foods and nutrients consumed in each eating occasion were assessed by 3-d dietary records. The prevalence of inadequate intake of twenty nutrients assessed by the age- and sex-specific reference values in the Japanese Dietary Reference Intakes was compared according to tertile categories of EI from snacks. Setting: A multi-regional dietary survey based on nursery schools in Japan. Participants A total of 187 boys and 191 girls aged 3–6 years. Results: EI from snacks accounted for 19·5 % (sd 6·9) of total daily EI. Confectionaries accounted for the largest part of EI from snacks (35·3 %), followed by milk (19·5 %). Relative to their energy contribution, snacks accounted for a small proportion for all nutrients examined, except for free sugar, calcium, SFA and riboflavin. Although a higher EI from snacks was associated with favourable profiles for intakes of calcium, iron, thiamine and riboflavin, excessive intakes of free sugar and Na were more prevalent among children with a higher EI from snacks. Conclusions: Although snacks are effective in meeting the requirement of some nutrients among Japanese nursery school children, snacks are generally not nutrient-dense and have an impact on excessive intake of some nutrients. There is hence room for improvement in food choices at snack time.