To identify temporal patterns of sleep and eating among school-aged children during school closure due to the COVID-19 pandemic and to examine their associations with lifestyle behaviours and dietary intake.

In this cross-sectional study, questionnaires were used to assess sleep and eating times, lifestyle behaviours, and dietary intake during school closure. Latent class analysis was performed to identify temporal patterns of sleep and eating based on self-reported clock times for wake-up, going to bed, and eating meals. Lifestyle behaviours and dietary intake were compared between latent classes.

48 primary and secondary schools in Japan.

6220 children (aged 8–15 years)

Four patterns, labelled “Very early (20% of children)”, “Early (24%)”, “Late (30%),” and “Very late (26%),” were identified and ordered according to the circadian timing. Latter patterns were characterised by later timings of sleep and eating, especially in clock times for wake-up, breakfast, and lunch compared to earlier patterns. Children with latter patterns had a less physically active lifestyle, longer screen time (>4 h/d), shorter study time (<2 h/d), and more frequent skipping of breakfast and lunch than those with earlier patterns. In addition, children with latter patterns had lower intakes of several vitamins, vegetables, fruits, fish and shellfish, and dairy products, and higher intakes of sugar and confectionaries and sweetened beverages.

More than half of the participants had later wake-up, breakfast, and lunch during school closure, which was associated with more unfavourable lifestyles and dietary intakes.

CyberKnife is the most advanced form of stereotactic body radiotherapy (SBRT) system that uses a robotic arm to deliver highly focused beams of radiation; however, a limitation is that it only irradiates from ceiling to floor direction. In patients with posterior lungs tumour who are positioned supine, normal lung tissue may suffer undesirable radiation injuries. This study compares the treatment planning between the prone set-up and the supine set-up for lung cancer in CyberKnife SBRT to decrease normal lung dose to avoid radiation side effects.

A human phantom was used to generate 108 plans (54 for prone and 54 for supine) using the CyberKnife planning platform. The supine and prone plans were compared in terms of the dosimetric characteristics, delivery efficiency and plan efficiency.

For posterior targets, the area of low-dose exposure to normal lungs was smaller in the prone set-up than in the supine set-up. V10 of the lungs was 7·53% and 10·47% (p < 0·001) in the anterior region, and 10·78% and 8·03% (p < 0·001) in the posterior region in the supine and prone set-up plans, respectively.

The comparison between the prone set-up and the supine set-up was investigated with regard to target coverage and dose to organs at risk. Our results may be deployed in CyberKnife treatment planning to monitor normal tissue dose by considering patient positioning. This may assist in the design of better treatment plans and prevention of symptomatic radiation pneumonitis in lung cancer patients.

Although there is growing evidence suggesting that eating patterns are important determinants of health status, comprehensive information on patterning of eating behaviours is almost lacking. The aim of this cross-sectional study was to describe eating patterns in Japan.

Information on actual eating behaviours was collected using 2-d dietary record in each season over a year (total 8 d). Eating occasions were defined as any discrete intake occasion (with a discrete start clock time and name) except for eating occasions consisting of water only, which were excluded.

Japan.

A nationwide sample of 4032 Japanese aged 1–79 years.

The mean value of eating frequency of meals (i.e. breakfast, lunch and dinner), snacks and total eating occasions was 2·94, 1·74 and 4·68 times/d, respectively. The mean clock time for the start of breakfast, lunch and dinner was 07.24, 12.29 and 19.15 h, respectively. The mean time spent consuming breakfast, lunch, dinner and snacks was 19, 25, 34 and 27 min/d, respectively. On average, variability (i.e. average of absolute difference from mean) of meal frequency was small compared with that of snack frequency and total eating frequency. Both mean variability of clock time for the start of eating (<1 h) and mean variability of time spent on meals (<10 min/d) were also small. Conversely, mean variability of time spent on snacks was large (>18 min/d).

The present findings serve as both a reference and an indication for future research on patterning of eating behaviours.

To examine the association between the amount of time spent at childcare and diet quality in 668 Japanese children aged 1·5–6 years.

A cross-sectional design was used. Dietary information was collected using dietary records (1 d for children aged 1·5–2 years and 2 d for children aged 3–6 years). Diet quality was assessed by counting the number of nutrients not meeting the Japanese Dietary Reference Intakes (DRI). Each child’s guardian reported the average amount of time spent at childcare per d for the previous 1 month.

In total, 315 childcare centres located in twenty-four areas in Japan.

In total, 753 children aged 1·5–6 years who attend childcare facilities.

After adjustment for potential confounders, OR for the low diet quality (≥ 5 of twenty nutrients not meeting DRI) in long (≥10 h/d) v. medium (8–10 h/d) childcare hours was 4·81 (95 % CI 1·96, 11·8) among children aged 5–6 years. There was no significant association in children aged 1·5–2 and 3–4 years.

This study showed that long time spent at childcare was strongly associated with low diet quality among children aged 5–6 years, but not those aged 1·5–2 and 3–4 years. More research is needed to clarify different associations in each age group.

To characterise different meal types by examining the contribution of specific meals to the total intakes and the nutritional quality of each meal.

A cross-sectional analysis was conducted based on dietary data collected using 4-d dietary record. Diet quality was assessed by the Healthy Eating Index-2015 and Nutrient-Rich Food Index 9.3.

Japan.

Adults aged 20–81 years (n 639).

Diet quality was, on average, highest for dinner, followed, in order, by lunch, breakfast and snacks. Breakfast, lunch, dinner and snacks, on average, accounted for 21 %, 32 %, 40 % and 11 % of total energy intake, respectively. For many nutrients, the percentage contribution to total intake did not vary within each meal, broadly in line with that for energy: 18–24 % for breakfast, 26–35 % for lunch, 35–49 % for dinner and 4–15 % for snacks. However, intakes of many foods largely depended on one meal type. The foods mainly eaten at dinner were potatoes, pulses, total vegetables, fish, meat and alcoholic beverages (52–70 %), in contrast to noodles (58 %) at lunch and bread (71 %) and dairy products (50 %) at breakfast. The foods mainly eaten at snacks were confectioneries (79 %) and sugar-sweetened beverages (52 %). Conversely, rice and eggs were more evenly distributed across three main meals (19–41 % and 30–38 %, respectively), while fruit and non-energetic beverages were more evenly distributed across all meal types (17–30 % and 19–35 %, respectively).

These findings provide the background information on each meal type in Japanese and may help inform the development of meal-based guidelines and public health messages.

To summarise the existing evidence of development, validation and current status of utilisation of dish-based dietary assessment tools.

Scoping review.

Systematic search using PubMed and Web of Science.

We identified twelve tools from seventy-four eligible publications. They were developed for Koreans (n 4), Bangladeshis (n 2), Iranians (n 1), Indians/Malays/Chinese (n 1), Japanese (n 3) and Chinese Americans (n 1). Most tools (10/12) were composed of a dish-based FFQ. Although the development process of a dish list varied among the tools, six studies classified mixed dishes based on the similarity of their characteristics such as food ingredients and cooking methods. Tools were validated against self-reported dietary information (n 9) and concentration biomarkers (n 1). In the eight studies assessing the differences between the tool and a reference, the mean (or median) intake of energy significantly differed in five studies, and 26–83 % of nutrients significantly differed in eight studies. Correlation coefficients for energy ranged from 0·15 to 0·87 across the thirteen studies, and the median correlation coefficients for nutrients ranged from 0·12 to 0·77. Dish-based dietary assessment tools were used in fifty-nine studies mainly to assess diet–disease relationships in target populations.

Dish-based dietary assessment tools have exclusively been developed and used for Asian-origin populations. Further validation studies, particularly biomarker-based studies, are needed to assess the applicability of tools.

Recent research supports the importance of PUFA intake in children, particularly of EPA and DHA; however, few verified methods to assess whether PUFA intake is adequate are available.

We assessed the correlation between serum PUFA and lipid concentrations with seafood and PUFA intake measured using a brief-type self-administered diet history questionnaire for Japanese preschool children (BDHQ3y).

Single centre birth cohort in Japan.

A total of 152 36-month-old Japanese children.

Average dietary intake of daily seafood, EPA and DHA was 13·83 (sd 10·36) g, 49·4 (sd 43·5) mg and 98·3 (sd 64·6) mg, respectively. Significant weak-to-moderate correlations were observed between dietary intake and serum EPA (Spearman rho = 0·41, P < 0·001; Pearson r = 0·44, P < 0·001); DHA (Spearman rho = 0·40, P < 0·001; Pearson r = 0·42, P < 0·001) and AA (arachidonic acid) (Spearman rho = 0·33, P < 0·001; Pearson r = 0·32, P < 0·001), whereas no significant correlation was observed for dihomo-γ-linolenic acid (DGLA) (Spearman rho = 0·06, P = 0·484; Pearson r = 0·07, P = 0·387). Correlations between seafood intake and serum EPA and DHA were also moderate (0·39–0·43). A negative correlation between serum TAGs and serum EPA, as well as positive correlations between serum cholesterol (total cholesterol, LDL and HDL) with serum EPA and DHA were observed, whereas no significant correlations between seafood intake and serum lipid profiles. Based on this model, we estimated 61–98 g/week of seafood intake is required to meet current EPA/DHA intake recommendations by the WHO (100–150 mg/d).

For children of 2–4 years of age, weekly intake of 61–98 g of seafood is required to meet WHO recommendations of EPA/DHA intake.

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.

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.

A multi-regional dietary survey based on nursery schools in Japan.

A total of 187 boys and 191 girls aged 3–6 years.

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.

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.

To develop a greenhouse gas emissions (GHGE) database for Japanese foods using three different approaches, compare the results of estimated diet-related GHGE and determine major food contributors among Japanese adults.

Cross-sectional. Three GHGE databases were developed: (1) a literature-based method including a literature review of life cycle assessment studies of Japanese foods and (2) production- and (3) consumption-based input–output tables (IOT)-applied methods using the Japanese IOT. All databases were linked to the Japanese food composition table and food consumption data. Diet-related GHGE was estimated based on each database and the 4-d dietary record data. Diet-related GHGE were compared in both total and food group level between the databases.

Japan.

392 healthy adults aged 20–69 years.

The mean diet-related GHGE significantly differed according to the calculation methods: 4145 g CO2-equivalent (CO2-eq)/d by the literature-based method, 4031 g CO2-eq/d by the production-based method and 7392 g CO2-eq/d by the consumption-based IOT-applied methods. It significantly differed in food group level as well. Spearman’s correlation coefficients between three methods ranged from 0·82 to 0·86. Irrespective of the methods, the top contributor to GHGE was meat (19·7–28·8 %) followed by fish and seafood (13·8–18·3 %).

Although the identified major food contributors to GHGE were comparable between the three methods, the estimated GHGE values significantly differed by calculation methods. This finding suggested that caution must be taken when interpreting the estimated diet-related GHGE values obtained using the different calculation methods of GHGE.

We assessed the validity of a recently developed dish composition database (DCD) against urinary biomarkers compared with a standard food composition database (FCD).

Intakes of protein, Na and K were estimated by 2 × 24 h urine collections and by 4 d dietary record data based on the DCD (including 128 dishes) or FCD (including 1878 foods).

Japan.

A total of 161 men and 163 women aged 20–69 years.

Compared with the 24 h urine-based estimates, the median intakes estimated using the DCD and FCD differed significantly for protein and Na in men and for Na and K in women. Deattenuated Spearman correlation coefficients using 24 h urine-based estimates for the intakes of protein, Na and K were lower in the DCD (respectively: 0·26, 0·15 and 0·44 in men; 0·22, 0·27 and 0·22 in women) than those in the FCD (respectively: 0·43, 0·40 and 0·59 in men; 0·33, 0·45 and 0·42 in women). When data on dish portion size reported by participants were used for estimation instead of standard portion-size data based on the DCD, the accuracy of the estimated median intakes did not change notably, whereas the deattenuated correlation coefficients improved (for protein, Na and K respectively: 0·32, 0·31 and 0·56 in men; 0·31, 0·41 and 0·39 in women).

The DCD supported by individual-level information on dish portion size showed fair to moderate validity in ranking individuals according to their intakes of protein, Na and K, similar to the FCD.

To develop a dish composition database (DCD) and assess its ability to estimate dietary intake.

The DCD was developed based on 16 d dietary records (DR). We aggregated all reported dishes into 128 dish codes and calculated mean food group and nutrient contents for each code. These data were used to calculate dietary intake in a different population that completed a 4 d DR. The estimated values were compared with those estimated using the standard food composition database (FCD) of Japan.

Japan.

A total 252 adults aged 31–81 years for the 16 d DR (3941 d in total) and 392 adults aged 20–69 years for the 4 d DR (1568 d in total) participated.

There were significant differences in median intakes between the DCD and the FCD for eighteen and twenty (of twenty-six) food groups and for twenty-nine and twenty-two (of forty-three) nutrients (including energy) in men and women, respectively. For food group intakes, Spearman correlation coefficients between the DCD and FCD ranged from 0·19 (animal fats) to 0·90 (fruits and alcoholic beverages) in men (median: 0·61) and from 0·25 (oils) to 0·89 (noodles) in women (median: 0·58). For nutrient intakes, the corresponding values ranged from 0·25 (retinol) to 0·90 (alcohol) in men (median: 0·60) and from 0·15 (retinol) to 0·74 (alcohol) in women (median: 0·53).

Whereas it is difficult to accurately estimate absolute dietary intake values using the present DCD, it has acceptable ability to rank the intakes of many food groups and nutrients.

Previous studies have associated dietary patterns with diabetes risk in Western countries, but such studies among the Japanese population are scarce. The present study aimed to investigate dietary patterns associated with abnormal glucose tolerance determined by elevated glycated Hb (HbA1c) levels.

The 2012 National Health and Nutrition Survey (NHNS) database was used for the cross-sectional study. Dietary patterns were analysed by factor analysis of twenty-five food items from the dietary intake survey and household-based semi-weighed dietary records. OR and 95 % CI for elevated HbA1c levels (≥6·5 %) according to dietary patterns were estimated using logistic regression models.

Japan.

The study population comprised 9550 Japanese aged ≥40 years registered in the nationwide NHNS.

Three dietary patterns were identified: (i) high-bread and low-rice; (ii) high-meat and low-fish; and (iii) vegetable. The high-bread and low-rice pattern, characterised by high frequent consumption of bread, milk and dairy products, and fruits, and low rice intake, was associated with marginally decreased prevalence of elevated HbA1c levels (Ptrend=0·047). The vegetable pattern, characterised by vegetables, mushrooms, soyabeans and soybean products, was significantly inversely associated with elevated HbA1c levels (4th v. 1st quartile: multivariable OR=0·68; 95 % CI 0·49, 0·95; Ptrend=0·007).

Our findings suggest that the vegetable pattern is associated with decreased prevalence of elevated HbA1c levels among Japanese.