Data Resource Profile: The Japan National Health and Nutrition Survey (NHNS)

An increasing trend of overweight and obesity in the Japanese incident end-stage kidney disease population

AIM

The global prevalence of overweight/obesity has been rising, and this trend is apparent in US and European incident end-stage kidney disease (ESKD) populations. We aimed to examine temporal trends in the prevalence of overweight/obesity and underweight among adult incident ESKD patients in Japan by year of dialysis initiation between 2006 and 2019 in comparison with those observed in the Japanese adult population during the same period.

METHODS

Using data from the Japanese Society of Dialysis Therapy Renal Data Registry and the National Health and Nutrition Survey, the sex-specific prevalence of overweight/obesity and that of underweight (BMI ≥ 25 kg/m2 and <18.5 kg/m2, respectively) were calculated, adjusted for age according to the 2019 Population Census via the direct method. Average annual percentage changes (AAPCs) and corresponding 95% confidence intervals (CIs) were calculated to examine trends.

RESULTS

From 2006 to 2019, the age-adjusted prevalence of overweight/obesity in the incident ESKD population increased for males (AAPC 3.36 [95% CI, 2.70 to 4.09]) and females (AAPC 2.86 [95% CI, 1.65 to 4.19]). The age-adjusted prevalence of overweight/obesity in the general population increased for males (AAPC 0.87 [95% CI, 0.26 to 1.42]) but not for females (AAPC 0.01 [95% CI, -0.55 to 0.57]). The age-adjusted prevalence of underweight in the incident ESKD population significantly decreased but was higher than that in the general population for both sexes.

CONCLUSION

An increasing trend of overweight/obesity was observed in the incident ESKD population in Japan. There is a pressing need to address both underweight and overweight/obesity in the incident ESKD population.

Dietary inflammatory index and number of functional teeth in middle-aged and older Japanese adults: A cross-sectional study using national survey data

PURPOSE

To determine whether the number of functional teeth, including the remaining natural teeth and prosthetically restored missing teeth, is associated with the dietary inflammatory index (DII), a quantitative measure of the inflammatory potential of the overall diet, in middle-aged and older Japanese adults.

METHODS

National survey data from a non-institutionalized Japanese population aged ≥45 years was analyzed. Multivariable linear regression analyses were performed to assess the association between the DII score, which was calculated based on dietary records, and the number of functional teeth, which was determined during dental examination. All regression analyses were stratified according to the age groups 45-64, 65-74, and ≥75 years. The association between functional tooth units (FTUs) and the DII was assessed using sensitivity analysis.

RESULTS

In total, 2407 individuals (1053 men and 1354 women; mean age = 66.7 years) were included. Multivariable analysis revealed that the number of functional teeth was significantly inversely associated with the DII score among participants aged ≥75 years (regression coefficient per increase of one in the number of functional teeth = -0.050; 95% confidence interval = -0.089 to -0.010). The number of functional teeth was not associated with the DII score in younger age categories (i.e., those aged 45-74 years). As in the primary analysis, the number of FTUs was significantly inversely associated with the DII score only in the group aged ≥75 years.

CONCLUSIONS

A greater number of functional teeth was associated with a lower DII (i.e., diet with greater anti-inflammatory potential) in Japanese adults aged ≥75 years.

Aging-related changes in protein and fat intake and their related meal types factors by longitudinal birth cohort analysis using the National Health and Nutrition Survey in Japan from 2001 to 2019

BACKGROUND

To provide seamless nutritional support from early adulthood to late adulthood in Japan, this study aimed to identify aging-related changes in protein and fat intake and meal types.

METHODS

Birth cohort analysis was conducted in this study. The protein intake, protein-to-energy ratio, fat intake, and fat-to-energy ratio in men and women from their 20s to 60s in 2001 was calculated using the data of the National Health and Nutrition Survey in Japan between 2001 and 2019 (n = 139,876, 47.0% men, mean age: 54.9 and 55.4 years for men and women, respectively). The intakes were calculated for every subsequent year, the aging-related changes were identified by age group, and the 99 food groups were classified into staple-focused meal types through factor analysis. The weighted average component value per 1 g of each food group was calculated, multiplied by the food weight, and totaled to determine the mean intake by meal type and to confirm the aging-related changes. The year when the slope changed before and after was identified through Joinpoint regression analysis.

RESULTS

The protein intake, protein-to-energy ratio, fat intake, and fat-to-energy ratio initially declined or remained unchanged with aging in almost all generations (20s to 60s in 2001) but began to increase after 8-15 years. The food groups were classified into rice, noodle, and bread types. The protein and fat intake from the noodle type initially showed a decreasing trend but began to increase with aging after 8-15 years in almost all generations in both sexes (p < 0.05 for difference in slope).

CONCLUSIONS

The increase of protein intake and protein-to-energy ratio and fat intake and fat-to-energy ratio over time observed among Japanese adults may be related to the increased intake of food groups from noodle type meals. Thus, considering the type of staple food (i.e., rice, noodles, or bread) and its combination with other foods when adhering to a balanced diet is necessary.

Metabolic Dysfunction-Associated Steatotic Liver Disease in Japan: Prevalence Trends and Clinical Background in the 10 Years before the Coronavirus Disease 2019 Pandemic

Background and Objectives: The trends in metabolic dysfunction-associated steatotic liver disease (MASLD) and related metabolic dysfunctions in Japan are unknown. Thus, we aimed to clarify these trends before the novel coronavirus disease 2019 pandemic in Japan. Materials and Methods: We included Japanese individuals aged 25-79 years who underwent health examinations at our center. We analyzed anthropometry, lifestyle-related disease, and nutritional intake in relation to MASLD trends from 2010-2019. Results: The prevalence of MASLD increased in all ages and body mass index (BMI) classes, reaching 30.3% in males and 16.1% in females, with MASLD accounting for 75% of steatotic liver cases and more than half of all type 2 diabetes mellitus (T2DM) and high waist circumference (HWC) cases. The increase in the prevalence of MASLD was thought to be largely attributable to an increase in that of the incidence of steatotic liver itself, and there was no increase in the prevalence of other factors, such as overweight, T2DM, hypertension, and dyslipidemia. The prevalence of glucose metabolic disorders (GMDs) and hypertension decreased. National nutritional data showed an increase in energy intake, total fat, saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids, which correlated with a decrease in GMDs. Salt intake also decreased, which correlated with hypertension. The MASLD group had a higher prevalence of all related metabolic factors than the non-MASLD group, especially HWC, T2DM, and hyperlipidemia. Conclusions: The prevalence of MASLD increased with that of steatotic liver, regardless of age or BMI. A relationship between increased dietary fat, increased steatotic liver, and decreased GMDs was suggested.

Seasonal variation in the intake of food groups and nutrients in Japan: A systematic review and meta-analysis

Background Seasonal variations could systematically bias dietary intakes. This systematic review aimed to determine seasonal variations in dietary intake among Japanese adults.Methods PubMed and Ichushi-Web databases were searched for studies reporting seasonal intakes of nutrients or food groups assessed by dietary records or 24-hour recalls. The protocol was registered with PROSPERO (CRD42022356084).Results Ten studies (eight studies on 1-31 nutrients and four on 2-15 food groups) met the inclusion criteria. Six studies included both sexes, whereas four investigated only females. The number of participants ranged from 25 to 459, and the number of dietary survey days in each season ranged from 1 to 14. For most nutrient and food groups, the reported seasonal variations were inconsistent across studies. The meta-analyses comparing differences in mean intakes between two seasons showed no significant differences in all comparisons or differences in only one comparison for most nutrients and food groups. Significant seasonal differences were observed for vegetables, fruits, and potatoes in five out of six comparisons, though the heterogeneity was high. Their biggest differences were as follows: 101 g/day more vegetable intake in summer than spring, 60 g/day more fruit intake in fall than spring, and 20.1 g/day more potato intake in fall than spring.Conclusion Reported seasonal variations were inconsistent across studies for most food groups and nutrients. Relatively distinct seasonal differences in mean intakes were observed for vegetables, fruits, and potatoes in meta-analyses. However, these results must be interpreted cautiously because of the high heterogeneity and limited representativeness.

Prevalence of hazardous drinking and suspected alcohol dependence in Japanese primary care settings

OBJECTIVE

We aimed to assess the prevalence of hazardous drinking and potential alcohol dependence among Japanese primary care patients, and their readiness to change and awareness of others' concerns.

METHODS

From July to August 2023, we conducted a multi-site cross-sectional study as a screening survey for participants in a cluster randomized controlled trial. The trial included outpatients aged 20-74 from primary care clinics. Using the Alcohol Use Disorders Identification Test (AUDIT) alongside a self-administered questionnaire, we evaluated the prevalence of hazardous drinking and suspected alcohol dependence, patients' readiness to change, and their awareness of others' concerns.

RESULTS

Among the 1388 participants from 18 clinics, 22% (95% confidence interval (CI): 20% to 24%) were identified as engaging in hazardous drinking or suspected of being alcohol dependent. As the AUDIT scores increased, so did their readiness to change. However, only 22% (95%CI: 16% to 28%) of those with scores ranging from 8 to 14 reported that others, including physicians, had expressed concerns about their drinking during the past year. For those with scores of 15 or higher, the figure was 74%.

CONCLUSIONS

This study underscores the need for universal or high-risk alcohol screening and brief intervention in Japanese primary care settings. Trial registry UMIN-CTR (https://www.umin.ac.jp/ctr/) (UMIN000051388).

Association between Number of Teeth and Eating out of Home: A 2019 Statistical Survey of the Japanese Representative Population

Eating out of home (EOH), with its diverse food options, can benefit those with difficulty preparing their meals, especially older adults. Oral health status may be a determinant of EOH, as food accessibility is influenced by oral health, but this association remains unclear. This cross-sectional study used merged data from two national statistical surveys conducted in 2019. Participants were individuals aged ≥ 65 years who responded to both surveys. The frequency of EOH ( Collapse

Key Words

• eating out
• older population
• oral health

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MESH Headings

• Aged
• Aged, 80 and over
• Female
• Humans
• Male
• Cross-Sectional Studies
• East Asian People
• Feeding Behavior
• Japan/epidemiology
• Meals
• Oral Health/statistics & numerical data
• Prevalence
• Surveys and Questionnaires
• Tooth Loss/epidemiology

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Grants

• 202209053A Ministry of Health, Labour and Welfare
• JPMJSP2114 Japan Science and Technology Agency

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Affiliation(s)

Anna Kinugawa Department of International and Community Oral Health, Graduate School of Dentistry, Tohoku University, 4-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Miyagi, Japan; (A.K.); (T.K.); (K.T.); (K.O.)
Takafumi Yamamoto Department of International and Community Oral Health, Graduate School of Dentistry, Tohoku University, 4-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Miyagi, Japan; (A.K.); (T.K.); (K.T.); (K.O.) Preventive Dentistry, Hokkaido University Hospital, Kita 13 jo Nishi 7 Chome, Kita-ku, Sapporo 060-8586, Hokkaido, Japan Department of Health Promotion, National Institute of Public Health, 2-Chome-3-6 Minami, Wako 351-0104, Saitama, Japan
Taro Kusama Department of International and Community Oral Health, Graduate School of Dentistry, Tohoku University, 4-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Miyagi, Japan; (A.K.); (T.K.); (K.T.); (K.O.) Division of Statistics and Data Science, Liaison Center for Innovative Dentistry, Graduate School of Dentistry, Tohoku University, 4-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Miyagi, Japan
Kenji Takeuchi Department of International and Community Oral Health, Graduate School of Dentistry, Tohoku University, 4-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Miyagi, Japan; (A.K.); (T.K.); (K.T.); (K.O.) Division of Statistics and Data Science, Liaison Center for Innovative Dentistry, Graduate School of Dentistry, Tohoku University, 4-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Miyagi, Japan
Ken Osaka Department of International and Community Oral Health, Graduate School of Dentistry, Tohoku University, 4-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Miyagi, Japan; (A.K.); (T.K.); (K.T.); (K.O.)

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Relationship between Household Shared Meal Frequency and Dietary Intake among Men and Women Aged ≥20 Years: Cross-Sectional Analyses Based on 2018 and 2019 National Health and Nutrition Surveys in Japan

This study aimed to examine the relationship between the frequency of household shared meals and the intake of 17 food groups and 21 nutrients. Participants were 3310 men and 3386 women ≥20 years old living in a household of ≥2 members from 2018 and 2019 National Health and Nutrition Surveys in Japan. A one-day household dietary record was used to classify an individual's shared meal frequency and dietary intake. A shared meal is defined as an eating occasion (i.e., breakfast, lunch, and dinner) where ≥1 food item-other than sugars, fats and oils, beverages, and condiments-was recorded with an assigned approximated shared proportion. The shared meal frequency for each individual was classified into one of four categories: 0, 1, 2, and 3 times/day. Dietary intake was compared across the shared meal categories adjusted for age, occupation, household size, meal skipping, snacking, residential areas, and within-household correlations. Both men and women who had more frequent shared meals showed higher intakes of potatoes, vegetables, mushrooms, and condiments but less confectioneries and beverages. A higher shared meal frequency was also related to a higher intake of many (12/21) nutrients (e.g., protein, dietary fiber, and potassium). However, in women, there was a positive association between shared meal frequency and sodium intake. A higher frequency of household shared meals may be related to a more favorable dietary intake; except for concerns about sodium intake in women.

Trends and Characteristics of Brown Rice Consumption among Adults in Japan: An Analysis of the National Health and Nutrition Surveys, 2012-2019

Brown rice is a familiar whole grain in Japan. We examined national trends in brown rice consumption among Japanese adults aged ≥20 years old, using individual-level data from the National Health and Nutrition Surveys conducted between 2012 and 2019. We employed multivariable logistic regression to identify factors associated with brown rice consumption. The 95th percentile of daily brown rice intake remained at 0.0 g throughout the study period. The percentage of brown rice consumers increased from 1.8% (95% confidence interval: 1.6-2.1) in 2012 to 2.6% (95% confidence interval: 2.0-3.4) in 2019. Compared with individuals who consumed only white rice, brown rice consumers had significantly higher mean intake levels of macronutrients, legumes, vegetables, fruits, and nuts. Brown rice consumption was positively associated with certain sociodemographic characteristics (being female, older age, residing in a major city, living without very young children, and having higher education levels) and health behaviors (lower body mass index, engaging in regular exercise, and being a former or never smoker). Despite its potential nutritional benefits in balanced diets, only a small fraction of adults in Japan consume brown rice, indicating a need for further promotion, particularly among individuals with characteristics associated with brown rice consumption.

Descriptive epidemiology of prevalence of exercise habits among participants with hypertension: The National Health and Nutrition Survey 2013-2018

Background

The current Japanese hypertension management guidelines (2019) recommend regular exercise for all patients with hypertension. However, limited evidence is available regarding the prevalence of exercise habits in these patients. Therefore, we examined the proportion of participants who met the recommendations on exercise in the Japanese hypertension management guidelines (2019) using a nationally representative sample.

Methods

Participants aged ≥20 years from the Japanese National Health and Nutrition Examination Survey conducted from 2013 to 2018 were included. Participants with hypertension were defined as those with blood pressure level ≥140/90 mmHg or those who used antihypertensive drugs. Adherence to the guideline recommendations, stratified by gender, age category, blood pressure level, and medication status, was examined.

Results

This study included 13,414 participants with hypertension (age 68.2 ± 11.7 years, 48.1% men). Among them, 31.8% of participants with hypertension (36.8% of men and 27.3% of women) met the guidelines. Regarding age, the 20-64 years age group had the lowest proportion of patients who met the guidelines (22.4%), followed by those in the 65-74 (37.7%) and ≥75 years age groups (34.5%). Adherence to the guidelines did not significantly differ according to blood pressure levels (<120/<80, 120-129/<80, 130-139/80-89, 140-159/90-99, and 160-179/100-109 mmHg) and presence of antihypertensive medications.

Conclusion

One-third of participants with hypertension engaged in exercise as recommended by the current hypertension management guidelines. Promotion of exercise therapy and monitoring exercise habits among participants with hypertension is warranted.

Data resource profile: Exercise habits, step counts, and sedentary behavior from the National Health and Nutrition Survey in Japan

The National Health and Nutrition Survey consistently assesses the prevalence of exercise habits, step counts, and sedentary behaviors in a strategically selected random sample of the Japanese population. The aim of this study was to provide descriptive epidemiological data on the average frequency of exercise habits, daily step counts, and sedentary behavior among Japanese adults from 2003 to 2019 using the National Health and Nutrition Survey database in Japan. Data were obtained from electronically available aggregate reports on the official survey website. To prepare for the third term of Health Japan 21, scheduled to start in 2024, we summarized population-level trends in exercise habits, step counts, and sedentary behavior among Japanese adults. The results could improve our understanding of trends in physical activity with respect to age and gender, providing a basis for public health monitoring and policy-making.

Nonalcoholic Fatty Liver Disease in Japan Continue to Increase Even after the Launch of Specific Health Checkups

Objective To examine the trends and relationships between nonalcoholic fatty liver disease (NAFLD) and hypertension, type 2 diabetes mellitus (T2DM), and dyslipidemia from fiscal year (FY) 2008, when specific health checkups (SHCs) were initiated in Japan, to FY 2019 and the relationship between NAFLD trends and dietary nutrition. Methods A total of 48,332 participants (25,121 men and 23,211 women) diagnosed with NAFLD who underwent health checkups, including ultrasonography, from FY 2008 to FY 2019 were included. A fatty liver was diagnosed using ultrasonography. The dietary nutrient intake status was based on data from the National Health and Nutrition Survey, Japan. Results Over 12 years, NAFLD prevalence increased from 26.9% to 43.1% in men (p<0.0001) and from 9.9% to 17.9% in women (p<0.0001) in all body mass index (BMI) groups except for obese II (according to the World Health Organization Asia-Pacific criteria) in men and underweight in women and almost all age groups. T2DM prevalence increased in men (from 9.0% to 10.7%, p=0.0234), and obesity and higher waist circumference rates increased in women (from 16.0% to 18.0%, p=0.0059 and from 8.1% to 10%, respectively, p=0.0006). The dietary nutrient intake increased with regard to the total fat, fat/energy ratio, saturated fatty acids, monounsaturated fatty acids, and n6/n3 fatty acid ratio in both men and women, and these nutrient trends were correlated with NAFLD prevalence (all p≤0.0005). Conclusion In Japan, NAFLD increased in both men and women regardless of the BMI and age, even after starting SHCs. An unbalanced fat intake may be one of the major reasons for this increase.

Analysing food groups and nutrient intake in adults who met and did not meet the daily recommended vegetable intake of 350 g: the 2016 National Health and Nutrition Survey in Japan

This study aimed to compare the differences in the intake of food groups and nutrients between Japanese adults who consumed the recommended daily vegetable intake (350 g/day) and those who did not. Dietary information was obtained from one-day dietary records collected from the 2016 National Health and Nutrition Survey, which was conducted in 46 prefectures in Japan. The participants aged ≥20 years (n = 21,606; 53.8% women) were classified into the < and ≥350 g/day groups. Inter-group differences for 17 food groups and 27 nutrients were assessed as percentages of consumers (food groups only) and energy-adjusted intake (units/MJ/d or % of total energy intake). Overall, 29% of participants consumed ≥350 g/day of vegetables. The ≥350 g/day group had a higher percentage of consumers and energy-adjusted intakes for all vegetable subgroups than the <350 g/day group. For other food groups, the ≥350 g/day group had higher percentages of consumers for all food groups, except for cereals, eggs, and condiments and seasonings, which showed no significant differences. However, the ≥350 g/day group had a significantly higher energy-adjusted intake for potatoes and other tubers, mushrooms, meats, and condiments and seasonings but a significantly lower value for cereals, eggs, savoury snacks and confectionaries, and beverages. The ≥350 g/day group had a significantly higher intake of almost all (25/27) nutrients, including sodium, than the <350 g/day group. Participants with vegetable intake ≥350 g/day might have a more favourable intake of food groups and nutrients; however, watching for salt intake is necessary when promoting vegetable intake.

Mortality from major causes and lifestyles by proportions of public assistance recipients among 47 prefectures in Japan: Ecological panel data analysis from 1999 to 2016

Objective

Comprehensive investigations of correlations between subnational socioeconomic factors and trends in mortality and lifestyle are important for addressing public health problems.

Methods

Forty-seven prefectures in Japan were divided into quartiles based on the proportion of public assistance recipients (PPAR). Age-standardized mortality from all causes, cancer, heart disease, and stroke in each prefecture were averaged for these quartiles in 2000, 2005, 2010, and 2015. Data from the National Health and Nutrition Survey were obtained for the following periods: 1999-2001, 2003-2005, 2007-2009, 2012, and 2016. Body mass index (BMI), intake of total energy, vegetable and salt, step count, and prevalence of current smoking and drinking for individuals aged 40-69 years age range were standardized for each prefecture and averaged by quartile. A two-way analysis of variance was used to assess differences in mortality and lifestyle across different years or periods, and quartiles.

Results

Mortality rates decreased, with the first (lowest) quartile showing the lowest rates, across all causes, cancer and heart diseases in both sexes. BMI exhibited an increase in men, whereas, BMI in women and other lifestyle factors in both sexes, excluding smoking and drinking in women, exhibited a decrease. BMI, vegetable and salt intake, total energy intake in men, and smoking in women varied across quartiles. Lower quartiles exhibited lower BMI and smoking prevalence but higher energy, vegetables, and salt intake.

Conclusions

PPAR exhibited favorable trends and significant differences in mortality related to all causes, cancer and heart disease across both sexes, along with BMI among women.

A scoping review of dietary assessment questionnaires potentially suitable for assessing habitual dietary intake in the National Health and Nutrition Survey, Japan

This scoping review aimed to identify questionnaire-based dietary assessment methods for use in the National Health and Nutrition Survey (NHNS) in Japan. The search was conducted in three databases (PubMed, Web of Science, and Ichushi) to identify questionnaire such as food frequency questionnaire and dietary history questionnaire validated against dietary recalls or food records for the intakes of both food groups and nutrients among Japanese adults. Study quality was assessed based on previously developed criteria. We extracted the questionnaire characteristics and the design and results of the validation studies. We identified 11 questionnaires, with the number of food items ranging from 40 to 196, from 32 articles of good quality. In the validation studies, participants were aged 30-76 years and 90% of the articles used ≥3 d dietary records as reference. The number of nutrients and food groups with a group-level intake difference within 20% against the reference method ranged from 1 to 30 and 1 to 11, respectively. The range of mean correlation coefficients between questionnaire and reference methods were 0.35-0.57 for nutrients and 0.28-0.52 for food groups. When selecting a survey instrument in the NHNS from the 11 existing questionnaires identified in this study, it is important to select one with high group-level comparison and correlation coefficient values on the intended assessment items after scrutinizing the design and results of the validation study. This review may serve as a reference for future studies that explore dietary assessment tools used for assessing dietary intake in specific representative populations.

Usual Nutrient Intake Distribution and Prevalence of Nutrient Intake Inadequacy among Japanese Children and Adults: A Nationwide Study Based on 8-Day Dietary Records

In this cross-sectional study, we evaluated nutrient intake adequacy in 4450 Japanese people aged 1-79 years. Dietary data was collected through non-consecutive 8-day weighed dietary records. Usual nutrient intakes from foods and beverages were estimated using the Multiple Source Method. Participant proportions with intakes below and above the Japanese Dietary Reference Intakes (2020) were calculated. Usual intakes of most nutrients were below the Estimated Average Requirement; calcium showed a high percentage of inadequacy across all sex and age groups (29-88%), and iron showed a high inadequacy among females aged 12-64 years (79-95%). The percentages of energy from protein and carbohydrates, dietary fibre, and potassium were typically below the lower limit of the Tentative Dietary Goal for Preventing Lifestyle-related Diseases (DG). Furthermore, over 20% of the participants exceeded the upper limit of the DG for the percentages of energy from total and saturated fats, and over 88% exceeded the upper limit of the DG for sodium. Japanese children and adults could improve their nutrient intake by increasing calcium, iron, dietary fibre, and potassium and reducing total and saturated fats and sodium. These findings can inform policies and interventions to improve nutrient intake in Japan.

Distribution of water turnover by sex and age as estimated by prediction equation in Japanese adolescents and adults: the 2016 National Health and Nutrition Survey, Japan

BACKGROUND

Although water is essential to the maintenance of health and life, standard values for human water requirements are yet to be determined. This study aimed to evaluate the distribution of water turnover (WT) according to sex and age, estimated using a prediction equation, in Japanese adolescents and adults.

METHODS

This cross-sectional study used data from the 2016 National Health and Nutrition Survey, Japan. Data were obtained from electronically available aggregated reports in the survey's official website. Participants aged between 15 and 80 years (10,546 men, 12,355 women) were selected using stratified random sampling. WT was calculated considering lifestyle and environmental factors, and using an equation (coefficient of determination = 0.471) previously developed by the international doubly labelled water (DLW) database group. As data on physical activity levels (PAL) were not collected in the survey, we used two evaluation methods: (1) energy intake assessed by dietary records and (2) total energy expenditure measured by the DLW method reported in previous Japanese studies, divided by basal metabolic rate predicted using the equation. We evaluated the relationship between WT and age using a restricted cubic spline model.

RESULTS

The average WT for the 15-19, 20-29, 30-39, 40-49, 50-59, 60-69, and ≥ 70 years was 3291, 3151, 3213, 3243, 3205, 3104, and 2790 ml/day, respectively in men, and 2641, 2594, 2741, 2739, 2753, 2707, and 2482 ml/day, respectively in women. In the spline model, WT showed an inverse association with age in men older than 50 years, whereas women showed a reverse U-shaped relationship between WT and age (p for non-linearity < 0.001), although results differed with body weight adjustment. Similar results were found for both PAL evaluation methods, and the range of WT per body weight was 45-56 ml/day for both sexes.

CONCLUSIONS

We determined the standard values of WT in Japanese population using a prediction equation and national large-scale survey data. These findings may be useful for setting water requirements for dietary guidelines in future.

Economic effects of dietary salt reduction policies for cardiovascular disease prevention in Japan: a simulation study of hypothetical scenarios

Objective

Reducing dietary salt intake is an essential population strategy for cardiovascular disease (CVD) prevention, but evidence on healthcare costs and outcomes is limited in Japan. We aimed to conduct a pilot economic evaluation under hypothetical scenarios of applying the salt reduction policies of England to Japan.

Methods

We examined salt reduction policies in England: media health promotion campaigns, front-of-pack labeling, and voluntary and mandatory reformulation with best-case and worst-case policy cost scenarios. We assumed that these policies were conducted in Japan for 10 years from 2019. We used published data on epidemiology and healthcare expenditures in Japan and the costs and effects of salt reduction policies in England, and defined the benefits as a decrease in national medical expenditures on CVD. We developed a Markov cohort simulation model of the Japanese population. To estimate the annual net benefits of each policy over 10 years, we subtracted monitoring and policy costs from the benefits. We adopted a health sector perspective and a 2% discount rate.

Results

The cumulative net benefit over 10 years was largest for mandatory reformulation (best case) at 2,015.1 million USD (with costs of USD 48.3 million and benefits of USD 2063.5 million), followed by voluntary reformulation (net benefit: USD 1,895.1 million, cost: USD 48.1 million, benefit: USD 1,943.2 million), mandatory reformulation (worst case, net benefit: USD 1,447.9 million, cost: USD 1,174.5 million, benefit: USD 2,622.3 million), labeling (net benefit: USD 159.5 million, cost: USD 91.6 million, benefit: USD 251.0 million), and a media campaign (net benefit: USD 140.5 million, cost: USD 110.5 million, benefit: USD 251.0 million). There was no change in the superiority or inferiority of policies when the uncertainty of model parameters was considered.

Conclusion

Mandatory reformulation with the best-case cost scenario might be economically preferable to the other alternatives in Japan. In future research, domestic data on costs and effects of salt reduction policies should be incorporated for model refinement.

Heterogeneity of gut microbiome compositions in the third decade of life in Japanese women: insights from a comparative analysis

The reasons for sex-associated gut microbiota differences have not been determined, and although sex hormones, diet, and other factors are considered to contribute to them, many of these factors are age related. To shed light on this complex interplay, our study aimed to investigate and compare the gut microbial compositions of males and females across a broad range of ages, aiming to identify sex-associated disparities and potential causal factors. Our study encompassed a comprehensive analysis of gut microbiota data obtained from 444 Japanese individuals, ranging from newborns to centenarians, sourced from the DNA Data Bank of Japan. We categorized the subjects into 13 distinct age groups and examined their relative microbial abundances, as well as alpha and beta diversities, in relation to sex and age. No difference was observed between gut microbiota relative abundances or alpha diversities between men and women at any age. However, the study showed that the heterogeneity of gut microbiota among women in their 20s was greater than in men. To confirm the general occurrence of this difference, we conducted additional analyses using seven datasets: three from Japan and four from other countries. Interestingly, this variance was particularly noticeable within Japanese women. We also showed a potential link between the observed heterogeneity and dietary fiber intake. It is hoped this study will provide clues that aid in the identification of factors responsible for sex-associated differences in gut microbiota compositions.

Trends in mortality from major causes and lifestyle factors by per capita prefectural income: Ecological panel data analysis from 1995 to 2016 in Japan

In Japan, trends in mortality and lifestyle have not been fully investigated according to subnational socioeconomic factors. Forty-seven prefectures (subnational units) were divided into quartiles by annual per capita prefectural income. Age-standardized mortality from all causes, cancer, heart disease, and stroke was averaged by quartile in 1995, 2000, 2005, 2010, and 2015. Data from the National Health and Nutrition Survey were obtained for periods 1 (1995-1997), 2 (1999-2001), 3 (2003-2005), 4 (2007-2009), 5 (2012), and 6 (2016). Body mass index (BMI), the intake of vegetables and salt, the number of steps, and the prevalence of current smoking and drinking for the 40-69-year age range were standardized by 10-year age groups in the 2010 Japanese population and were averaged by quartile. Differences in mortality and lifestyle by year and period, and quartile were tested using a two-way analysis of variance. Mortality decreased in both sexes and mortality in men from all causes, cancer, and stroke differed by quartile, with mortality highest in the first (lowest) quartile. BMI in men and smoking prevalence in women increased, whereas remaining lifestyle factors except for the prevalence of drinking decreased in women. BMI and the number of steps in both sexes and current smoking prevalence in women differed by quartile, with lower quartiles showing a higher BMI and fewer step counts. In conclusion, favorable trends and significant differences in mortality from all causes, cancer, and stroke in men and BMI in women were observed by per capita prefectural income level.

Linking coastal environmental and health observations for human wellbeing

Coastal areas have long been attractive places to live, work, and recreate and remain so even in the face of growing threats from global environmental change. At any moment, a significant portion of the human population is exposed to both positive and negative health effects associated with coastal locations. Some locations may be "hotspots" of concern for human health due to ongoing climatic and other changes, accentuating the need for better understanding of coastal environment-human health linkages. This paper describes how environmental and health data could be combined to create a coastal environmental and human health observing system. While largely based on information from the US and Europe, the concept should be relevant to almost any coastal area. If implemented, a coastal health observing system would connect a variety of human health data and environmental observations for individuals and communities, and where possible cohorts. Health data would be derived from questionnaires and other personal sources, clinical examinations, electronic health records, wearable devices, and syndromic surveillance, plus information on vulnerability and health-relevant community characteristics, and social media observations. Environmental data sources would include weather and climate, beach and coastal conditions, sentinel species, occurrences of harmful organisms and substances, seafood safety advisories, and distribution, proximity, and characteristics of health-promoting green and blue spaces. Where available, information on supporting resources could be added. Establishment of a linked network of coastal health observatories could provide powerful tools for understanding the positive and negative health effects of coastal living, lead to better health protections and enhanced wellbeing, and provide significant benefits to coastal residents, including the historically disadvantaged, as well as the military, hospitals and emergency departments, academic medical, public health, and environmental health programs, and others. Early networks could provide best practices and lessons learned to assist later entries.

Trends in Mean Energy and Nutrient Intakes in Japanese Children and Adolescents: The National Health and Nutrition Survey, 1995-2019

This study aimed to describe the national trends in mean energy and nutrient intakes in Japanese children and adolescents from 1995 to 2019. We used data obtained from the National Health and Nutrition Survey and included 54,871 participants aged 1-19 years. The dietary intake was estimated using a 1-day, semi-weighed, household-based, dietary record. The trends of mean energy and nutrient intakes were analyzed using the Joinpoint Regression Program. A declining trend in the mean energy intake was observed in toddlers aged 1-6 years, school girls aged 7-14 years, and adolescent girls aged 15-19 years, while the mean energy intake from protein, fat, and carbohydrates changed little over time. The mean salt equivalent showed a decreasing trend in all age groups, although the 2019 mean values were above the tentative dietary goal for preventing lifestyle-related diseases, especially in adolescent boys. Declining trends in mean vitamin (vitamin A, vitamin B12, folate, vitamin D, and vitamin K) and mineral (calcium, iron, and copper) intakes were observed, while trends in the mean vitamin B6 and zinc intakes were unchanged since 2001. Continuous monitoring of dietary intake and further research are required to raise awareness of unhealthy diet habits and to improve the food environment for the healthy growth and development of children and adolescents.

Current dietary intake of the Japanese population in reference to the planetary health diet-preliminary assessment

Introduction

We sought to assess the Japanese diet by examining the current dietary intake in Japan using the global reference diet from the EAT-Lancet Commission (Planetary Health Diet; PHD), from the perspective of protein intake in different age groups.

Methods

Average dietary intake by food group in the Japan National Health and Nutrition Survey 2019 (NHNS 2019) was converted to the PHD food groups, and the diet gap (DG) (%) of the global reference of the PHD was calculated by age group.

Results

Although the DG of the intake was excessive compared with the global reference of the PHD in most food groups in all age groups (7.1-416%), the intake exceeded the upper limit of the range only for red meat (640%). Red meat had the highest DG among subjects in their 40s, although the DG decreased with increasing age. Protein intake was within the possible range and did not greatly exceed the recommended dietary intake in the Japanese standard.

Discussion

The current Japanese diet contains an excessive intake of red meat in terms of the global reference of the PHD. This trend is similar to that previously reported in various western regions and countries. However, the Japanese diet does not significantly exceed the recommended protein intake for Japanese people, suggesting that the PHD is an environmentally friendly and healthy choice for younger and older age groups in an aging Japanese society. Policy makers need to develop sustainable and healthy food-based dietary guidelines in addition to providing food and nutrition education and developing a food environment that encourages sustainable and healthy choices to support dietary change.

Modelling of salt intake reduction by incorporation of umami substances into Japanese foods: a cross-sectional study

BACKGROUND

Evidence has demonstrated that excess sodium intake is associated with development of several non-communicable diseases. The main source of sodium is salt. Therefore, reducing salt intake in foods is an important global public health effort to achieve sodium reduction and improve health. This study aimed to model salt intake reduction with 'umami' substances among Japanese adults. The umami substances considered in this study include glutamate or monosodium glutamates (MSG), calcium diglutamate (CDG), inosinate, and guanylate.

METHODS

A total of 21,805 participants aged 57.8 years on average from the National Health and Nutrition Survey was used in the analysis. First, we employed a multivariable linear regression approach with overall salt intake (g/day) as a dependent variable, adjusting for food items and other covariates to estimate the contribution of salt intake from each food item that was selected through an extensive literature review. Assuming the participants already consume low-sodium products, we considered three scenarios in which salt intake could be reduced with the additional umami substances up to 30%, 60% and 100%. We estimated the total amount of population-level salt reduction for each scenario by age and gender. Under the 100% scenario, the Japan's achievement rates against the national and global salt intake reduction goals were also calculated.

RESULTS

Without compromising the taste, the 100% or universal incorporation of umami substances into food items reduced the salt intake of Japanese adults by 12.8-22.3% at the population-level average, which is equivalent to 1.27-2.22 g of salt reduction. The universal incorporation of umami substances into food items changed daily mean salt intake of the total population from 9.95 g to 7.73 g: 10.83 g to 8.40 g for men and 9.21 g to 7.17 g for women, respectively. This study suggested that approximately 60% of Japanese adults could achieve the national dietary goal of 8 g/day, while only 7.6% would meet the global recommendation of 5.0 g/day.

CONCLUSIONS

Our study provides essential information on the potential salt reduction with umami substances. The universal incorporation of umami substances into food items would enable the Japanese to achieve the national dietary goal. However, the reduced salt intake level still falls short of the global dietary recommendation.

Projections of future coronary heart disease and stroke mortality in Japan until 2040: a Bayesian age-period-cohort analysis

Background

We aimed to estimate the future burden of coronary heart disease (CHD) and stroke mortalities by sex and all 47 prefectures of Japan until 2040 while accounting for effects of age, period, and cohort and integrating them to be at the national level to account for regional differences among prefectures.

Methods

We estimated future CHD and stroke mortality projections, developing Bayesian age-period-cohort (BAPC) models in population and the number of CHD and stroke by age, sex, and all 47 prefectures observed from 1995 to 2019; then applying these to official future population estimates until 2040. The present participants were all men and women aged over 30 years and were residents of Japan.

Findings

In the BAPC models, the predicted number of national-level cardiovascular deaths from 2020 to 2040 would decrease (39,600 [95% credible interval: 32,200-47,900] to 36,200 [21,500-58,900] CHD deaths in men, and 27,400 [22,000-34,000] to 23,600 [12,700-43,800] in women; and 50,400 [41,900-60,200] to 40,800 [25,200-67,800] stroke deaths in men, and 52,200 [43,100-62,800] to 47,400 [26,800-87,200] in women).

Interpretation

After adjusting these factors, future CHD and stroke deaths will decline until 2040 at the national level and in most prefectures.

Funding

This research was supported by the Intramural Research Fund of Cardiovascular Diseases of the National Cerebral and Cardiovascular Center (21-1-6, 21-6-8), JSPS KAKENHI Grant Number JP22K17821, and the Ministry of Health, Labour and Welfare Comprehensive Research on Life-Style Related (Diseases Cardiovascular Diseases and Diabetes Mellitus Program), Grant Number 22FA1015.

Nutritional Adequacy Assessment of the Japanese Diet Using the Number of Dishes Compared to Existing Dietary Diversity Indices: A Cross-Sectional Analysis from the 2012 National Health and Nutrition Survey, Japan

The Japanese diet has attracted attention as a factor contributing to the Japanese population's longevity. A typical Japanese meal, traditionally called "ichiju-sansai," is composed of various dishes. This study assessed the nutritional adequacy of the Japanese diet using the number of dishes in all meals (NDAM) compared to existing dietary diversity indices (DDIs). This cross-sectional study used data from the 2012 National Health and Nutrition Survey. A total of 25,976 participants aged ≥20 y were included in this study. NDAM was calculated for whole dishes or single foods (except supplements and beverages) from one-day weighted dietary records. The food variety score (FVS), number of foods, dietary diversity score (DDS), and number of food groups are some of the existing DDIs. NDAM had relatively high positive correlation coefficients with potassium, magnesium, and dietary fiber. The partial correlation coefficients with an indicator of the overall nutrient adequacy of NDAM was 0.42 for men and 0.42 for women. It was almost the same as that of the FVS (men: 0.44, women: 0.42) and DDS (men: 0.44, women: 0.43). On the other hand, NDAM, similar to existing DDIs, was also positively correlated with nutrient restriction in both sexes. These findings indicate that the nutrient adequacy of NDAM is similar to that of the existing DDIs. Because of the higher sodium intake and cholesterol intake in higher NDAM and existing DDIs, the effect of higher NDAM on health outcomes must be investigated in future studies.

Marital status, household size, and lifestyle changes during the first COVID-19 pandemic: NIPPON DATA2010

Stay-at-home strategies taken during the COVID-19 pandemic changed our lifestyle drastically. Although marital status and household size are important social determinants of health that affect lifestyle, their impacts on lifestyle during the pandemic are still unclear. We aimed to evaluate the association between marital status, household size, and lifestyle changes during the first pandemic in Japan. Questionnaire surveys on lifestyle changes from before to during the first COVID-19 pandemic were conducted on October 2020 in Japan. Classified into age groups, multivariable logistic regression analysis was performed to examine the combined association of marital status and household size on lifestyle, adjusted for potential confounders including socioeconomic factors. In our prospective cohort study, 1928 participants were included. Among older participants, the singles living alone were likely to perceive more unhealthy lifestyle changes (45.8%), compared with the married (33.2%), and significantly associated with at least one unhealthy change [adjusted odds ratio (OR): 1.81, 95% confidence interval (CI): 1,18-2.78], mainly due to decreased physical activity and increased alcohol consumption. Meanwhile, the younger participants showed no significant association between marital status, household size, and unhealthy changes, while those living alone had 2.87 times higher odds of weight gain (≥ 3 kg) than the married (adjusted OR: 2.87, 95% CI: 0.96-8.54) during the pandemic. Our findings suggest that older singles living alone are potentially vulnerable subgroups to drastic social changes which warrant special attention to prevent adverse health outcomes and additional burden on health systems in the following future.

Body weight and lifestyle changes under the COVID-19 pandemic in Japan: a cross-sectional study from NIPPON DATA2010

OBJECTIVES

The COVID-19 pandemic has had an impact on people's lifestyles such as causing body weight changes. This study examined associations among lifestyle changes and body weight during the COVID-19 pandemic among the Japanese population.

DESIGN

A cross-sectional study.

SETTING

A nationwide survey of the general Japanese population.

PARTICIPANTS

Total participants were 2244 men and women, of which 911 young/middle-aged (30-69 years old) and 899 older adults (70 years and older) were analysed separately.

OUTCOME

Changes in lifestyle (physical activity, dietary habits and alcohol intake) and body weight during the first wave of COVID-19 in spring 2020.

RESULTS

Under the COVID-19 pandemic, 24.1% and 10.1% of Japanese respondents reported weight gain and reduction, respectively. Multivariable-adjusted stepwise logistic regression analyses revealed that the young/middle-aged respondents in the group increased body weight, weight gain was significantly associated with decrease in physical activity (OR 4.01, 95% CI 2.83 to 5.69) and both increase (OR 5.82, 95% CI 3.85 to 8.80) and decrease (OR 2.73, 95% CI 1.52 to 4.93) in eating between meals. In the group that decreased body weight, body weight reduction was significantly associated with increase in physical activity (OR 3.66, 95% CI 1.94 to 6.90), decrease in eating between meals (OR 5.97, 95% CI 3.11 to 11.48) and both increase and decrease in alcohol intake in the young/middle age. For the older adults, body weight gain was higher in women than in men, and significantly associated with higher quartile of regional COVID-19 infection, decrease in physical activity (OR 2.98, 95% CI 1.98 to 4.49), increase in home-cooked meals and increase in eating between meals (OR 4.22, 95% CI 2.55 to 6.99). On the other hand, body weight reduction was significantly associated with decreases in physical activity (OR 2.63, 95% CI 1.62 to 4.27), home-cooked meals and eating between meals (OR 1.95, 95% CI 1.05 to 3.61) in the older adults.

CONCLUSION

Changes in physical activity and eating between meals were associated with body weight change under the COVID-19 pandemic among Japanese.

Trends in Food Group Intake According to Body Size among Young Japanese Women: The 2001-2019 National Health and Nutrition Survey

Unlike in many industrialised countries, the high proportion of young women who are underweight in Japan has been a long-term problem. We evaluated trends in food group intake according to body size among young Japanese women using data from the National Health and Nutrition Survey 2001-2019. Overall, 13,771 Japanese women aged 20-39 years were included. A 1-day household-based dietary record was used to estimate food intake. Foods were classified into 34 groups based on the Standard Tables of Food Composition in Japan. The trend of food group intake was analysed using the Joinpoint Regression Program. The proportion of young women who were underweight was consistently around 20%, while obesity among young women increased between 2001 (10%) and 2019 (13%). A decreased trend in fish and shellfish and seaweed intake and an increased trend in meat and soft drink intake were observed among young women. Decreased trends in the intake of fruit and dairy products were observed in young women who were not obese. An increased trend in the intake of confectionaries was observed in young women who were obese. This study suggests that the types of unhealthy eating habits may differ according to body size among young Japanese women.

Estimation of the Effect of Salt-Intake Reduction on Cardiovascular Mortality Decline between 1950 and 2017 in Japan: A Retrospective Simulation Study

In Japan, a decrease in cardiovascular mortality has coincided with reduced population salt intake since the 1950s. The purpose of this study was to quantify the effect of reduced population salt intake on the long-term trends of cardiovascular mortality. Using government statistics and epidemiological study results in people of 20–69 years old from 1950 to 2017, including the National Health and Nutrition Survey, we developed a system dynamics model of age-specific cardiovascular mortality and salt intake. We estimated the period and cohort effects on mortality and calibrated the model for the historical mortality rate. We then simulated the counterfactual scenario of no decrease in salt intake to estimate the reduction in cardiovascular deaths associated with decreased mean salt intake. Compared with the base run and calibrated to the actual data, approximately 298,000 and 118,000 excess deaths were observed in men and women, respectively, assuming no change in salt intake over the entire period. The model suggests that the decline in salt intake since the 1950s has contributed to a non-negligible reduction in cardiovascular mortality.

Association between Food Sources of Free Sugars and Weight Status among Children and Adolescents in Japan: The 2016 National Health and Nutrition Survey, Japan

This cross-sectional study aimed to investigate the relationship between food sources of free sugars and weight status among children and adolescents aged 2–19 years in Japan (1438 males and 1340 females) from the 2016 National Health and Nutrition Survey, Japan. We estimated the percentage of energy intake (% E) from free sugars from total food sources (FS_total), solid foods (FS_solids), and beverages (FS_liquids), using one-day weighed dietary record data. Weight status was determined based on body mass index (BMI) z-scores and the prevalence of overweight and obesity. The mean energy intakes of FS_total, FS_solids, and FS_liquids were 5.8%, 4.1%, and 1.8% in males and 6.2%, 4.6%, and 1.6% in females, respectively. After controlling for potential confounding factors, including energy intake, there was no association of free sugars intake from all food sources with BMI z-scores or with the prevalence of overweight and obesity, except for a marginal association between higher FS_solids and lower estimated BMI z-scores in females (p = 0.05). The present findings indicate that among children and adolescents in Japan, who have a relatively low mean intake of free sugars, consuming free sugars from any food source is unlikely to have an adverse effect on weight status.

Reduction of Cardiovascular Events and Related Healthcare Expenditures through Achieving Population-Level Targets of Dietary Salt Intake in Japan: A Simulation Model Based on the National Health and Nutrition Survey

Reducing population dietary salt intake is expected to help prevent cardiovascular disease and thus constrain increasing national healthcare expenditures in Japan’s super-aged society. We aimed to estimate the impact of achieving global and national salt-reduction targets (8, <6, and <5 grams/day) on cardiovascular events and national healthcare spending in Japan. Using published data including mean salt intake and systolic blood pressure from the 2019 National Health and Nutrition Survey, we developed a Markov model of a closed cohort of adults aged 40−79 years in 2019 (n = 66,955,000) transitioning among six health states based on the disease course of ischemic heart disease (IHD) and stroke. If mean salt intake were to remain at 2019 levels over 10 years, cumulative incident cases in the cohort would be approximately 2.0 million for IHD and 2.6 million for stroke, costing USD 61.6 billion for IHD and USD 104.6 billion for stroke. Compared with the status quo, reducing mean salt intake towards the targets over 10 years would avert 1−3% of IHD and stroke events and save up to 2% of related national healthcare costs. Attaining dietary salt-reduction goals among adults would yield moderate health economic benefits in Japan.

Evaluation of pre-Games effects of the Tokyo 2020 Olympic Games on Japanese population-level physical activity: a time-series analysis

Background

The Olympic Games represent an opportunity to create a ‘physical activity legacy’ that promotes physical activity at the population level in the host nations and cities. However, previous studies showed little increase in population-level physical activity following the Olympics. The upsurge of public interest in sports and physical activity participation before the Olympics may diminish rapidly following the Games. We examined the pre-Games effects of the Olympics on Japanese population-level physical activity after the announcement of Tokyo’s successful bid for the 2020 Olympic and Paralympic Games in September 2013.

Methods

We used publicly available data from serial cross-sectional surveys conducted with nationally or regionally representative samples in Japan seven years before and after the announcement (from 2006–2020). The outcomes were 1) daily step counts and 2) exercise habit prevalence (≥ 30 min/day, ≥ 2 days/week, and over a year) from the National Health and Nutrition Surveys Japan (NHNS-J; 14 time points; aggregated data); and 3) sports participation (at least once a week) from the National Sports-Life Survey conducted every two years (NSLS; eight time points; individual-level data of 18,867 adults) and from the Public Opinion Survey on Sports Participation of Tokyo Residents (POSSP; eight time points; aggregated data). Age- and gender-adjusted regression models were used to estimate changes in the outcomes before and after the announcement.

Results

There were no significant pre-Games effects of the Olympics on national-level physical activity participation among Japanese adults. Sports participation (56.4% and 57.5%, respectively; P = 0.518), daily steps (6,535 and 6,686 steps/day; P = 0.353), and exercise habit (30.7% and 29.1%, P = 0.309) did not change significantly before and after the announcement. Although an increase in sports participation among Tokyo residents was not found in the NSLS (61.5% and 59.3%, P = 0.227), it was observed in the POSSP (49.1% and 57.7%, P = 0.019). Nonetheless, this increase might not be related to the pre-Games effects since the trend diminished following the announcement.

Conclusions

Population-level physical activity did not show significant changes until 2020. Realising the physical activity legacy of an Olympics may require strategic promotion and cross-agency partnership implementation in the pre- and post-event period.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12966-022-01332-x.

An assessment of implementation gaps and priority recommendations on food environment policies: the Healthy Food Environment Policy Index in Japan

OBJECTIVE

The current study aimed to evaluate policies and actions for food environments by the Japanese Government using the Healthy Food Environment Policy Index (Food-EPI).

DESIGN

Public health experts rated the extent of implementation of food environment-related Policy and the Infrastructure-support components, compared with international best practices. Subsequently, the experts proposed and prioritised future actions to address implementation gaps in an online workshop.

SETTING

Japan.

PARTICIPANTS

A total of sixty-six experts rated policy implementation by the Japanese Government and twenty-three participated in the workshop on future actions.

RESULTS

The implementations of regulations on unhealthy foods and non-alcoholic beverages were rated low in the domains of Food composition, Food labelling and Food promotion, Food prices and Food retail in the Policy component. The implementations of several domains in the Infrastructure-support component were, overall, rated at a higher level, specifically for monitoring and intelligence systems. Based on the rating, reducing health inequalities by supporting people, both economically and physically, was the highest priority for future actions in both components.

CONCLUSIONS

The current study found that Japan has a robust system for long-term monitoring of population health but lacks regulations on unhealthy foods and non-alcoholic beverages compared with international best practices. The current study confirmed the importance of continuous accumulation of evidence through national monitoring systems. Developing comprehensive regulations to restrict food marketing, sales and accessibility of unhealthy foods and non-alcoholic beverages is needed to improve the health of food environments in Japan.

Development of a Digital Photographic Food Atlas as a Portion Size Estimation Aid in Japan

This study aimed to develop a digital photographic food atlas as a portion size estimation aid. Commonly consumed foods were identified from the 5512-day weighed dietary records of 644 Japanese adults. Portion sizes were determined based on the market research and distribution of food consumption in the dietary records. Each food item was classified into one of two photo types: a series of photographs showing gradually increasing portion sizes or guide photographs representing a range of portion sizes and food varieties in one photograph. Photographs of the food were taken at an angle of 42°, along with appropriate reference objects such as chopsticks. In total, 209 food and dish items were included in the food atlas. Series of photographs were taken for 105 items that are not usually served in predetermined amounts (e.g., rice and pasta), whereas guide photographs were taken for 104 items usually served in predetermined amounts (e.g., bananas and cookies). Moreover, photographs were taken for 12 kinds of household measurement items, such as cups and glasses. The food atlas could be a valuable tool for estimating the portion size in dietary surveys. Evaluating the validity of this food atlas for portion size estimation is warranted.

Trends and Disparities in Adult Body Mass Index Across the 47 Prefectures of Japan, 1975-2018: A Bayesian Spatiotemporal Analysis of National Household Surveys

Background

Among high-income countries, Japan has a low prevalence of obesity, but little is understood about subnational trends and variations in body mass index (BMI), largely owing to the lack of data from representative samples of prefectures. We aimed to examine long-term trends and distributions of adult BMI at the prefecture level in Japan from the late 1970s using a spatiotemporal model.

Methods

We obtained cross-sectional data for 233,988 men and 261,086 women aged 20-79 years from the 44 annual National Health and Nutrition Surveys (NHNS) conducted during 1975-2018. We applied a Bayesian spatiotemporal model to estimate the annual time series of age-standardized and age-specific mean BMI by 20-year age group and sex for each of the 47 prefectures. We assessed socioeconomic inequalities in BMI across prefectures using the concentration index, according to population density.

Results

In men, the age-standardized prefectural mean BMI ranged from 21.7 kg/m² (95% credible interval, 21.6-21.9) to 23.1 kg/m² (22.9-23.4) in 1975 and from 23.5 kg/m² (23.3-23.7) to 24.8 kg/m² (24.6-25.1) in 2018. In women, the age-standardized prefectural mean BMI ranged from 22.0 kg/m² (21.9-22.2) to 23.4 kg/m² (23.2-23.6) in 1975 and from 21.7 kg/m² (21.6-22.0) to 23.5 kg/m² (23.2-23.8) in 2018. Mean BMI was highest in the southernmost prefecture for most of the study period, followed by northeast prefectures. The increase in mean BMI was largest in southwest prefectures, which caught up with northeast prefectures over time. The concentration index was negative, indicating higher BMI in less-populated prefectures. Absolute values of the concentration index were greater in women than in men and increased over time.

Conclusions

There were variations in adult mean BMI across prefectures, and geographic distributions changed over time. Further national and local efforts are needed to address the rising trend in mean BMI, particularly among men in rural prefectures, and socioeconomic inequalities among women. Bayesian hierarchical modeling is useful for reconstructing long-term spatiotemporal trends of mean BMI by integrating small-sized survey samples at the prefecture level in the NHNS.

Trends in dietary salt sources in Japanese adults: data from the 2007-2019 National Health and Nutrition Survey

Identifying trends in dietary salt sources is essential for effectively reducing salt/Na intake. This study aimed to examine the trends in dietary salt sources among Japanese adults using the 2007-2019 National Health and Nutrition Survey data collected from 95 581 adults aged ≥ 20 years. Dietary intake was estimated using the 1-d household-based dietary record. Foods reported as potential sources of salt intake in Japan and other countries were categorised into twenty-one groups. Salt intake for each food group was adjusted using the density method based on the energy intake. Trends in dietary salt intake based on food sources by sex and age groups (20-39 years, 40-59 years and ≥ 60 years) were analysed using the Joinpoint Regression Program. Salt intake for each age group in both men and women decreased from 2007 (5·3 g/1000 kcal-6·4 g/1000 kcal) to 2019 (4·9 g/1000 kcal-5·6 g/1000 kcal). The major dietary source of salt continued to be seasonings such as soya sauce and soyabean paste (approximately 70 %). Salt intake from seasonings decreased over time in adults aged ≥ 40 years but did not change in those aged 20-39 years. Additionally, a decreasing salt intake from unprocessed fish and shellfish and an increasing salt intake from unprocessed meat were observed across all age categories for both sexes. This study demonstrated that a strategy targeting different age groups may be needed to reduce salt consumption from seasonings among the Japanese population. Further studies on salt content in seasonings and continued monitoring of trends in dietary salt sources are required.

Trends in Prevalence, Treatment, and Control of Hypertension According to 40-Year-Old Life Expectancy at Prefectures in Japan from the National Health and Nutrition Surveys

The prevalence of hypertension has been decreasing in Japan due to improved medical treatment and a decrease in dietary salt intake. However, disparities in the prevalence, treatment, and control of hypertension are expected to occur in different regions. This study aimed to investigate the trends in the prevalence, treatment, and control of hypertension at the prefectural level of life expectancy among Japanese population. We used data from the National Health and Nutrition Survey and analysed the individual survey information of individuals aged 40–69 years by dividing it into six terms, i.e., 1995–1997, 1999–2001, 2003–2005, 2007–2009, 2012, and 2016. Prefectures were classified into four groups according to their 40-year-old life expectancy in 2000. Outcome values were standardised to the population by 10-year age groups in 2010, and they were tested by two-way analysis of variance according to six terms and life expectancies. The prevalence of hypertension tended to decrease, especially among women, whereas the treatment and control tended to improve from the first to the sixth period in both men and women. The prevalence and treatment of hypertension in men with longer life expectancy tended to be lower than that in other groups, and there was no obvious difference in the control. In women, there were no obvious differences in the prevalence, treatment, or control. Reducing the prevalence of hypertension by improving lifestyle factors, such as high salt intake in each prefecture with a relatively short life expectancy, may be important to resolve the disparity in life expectancy among prefectures.

Association between exposure to secondhand smoking at home and tooth loss in Japan: A cross-sectional analysis of data from the 2016 National Health and Nutrition Survey

INTRODUCTION

Tooth loss affects oral health and physical and social functions. With widespread population aging, its prevalence is increasing. Secondhand smoking is a risk factor for oral diseases; however, in Japan, there are currently no regulations restricting exposure to secondhand smoke at home. This cross-sectional study examined the association between secondhand smoking at home and tooth loss among Japanese adults.

METHODS

The study examined secondary data from the 2016 National Health and Nutrition Survey, Japan. The self-reported responses of 18812 non-smokers aged ≥20 years were analyzed. The association between exposure to secondhand smoke at home and number of teeth was examined through multiple linear regression with multiple imputation. To obtain a more normal distribution, logarithmic transformation was applied to the number of teeth that deviated substantially from a normal distribution. Adjustments were made for sex, age, occupation, household size, dental check-up within the past year, and exposure to secondhand smoke outside the home.

RESULTS

Overall, 8.4% of the respondents were exposed to secondhand smoking at home almost every day; this percentage was larger among younger respondents, who also had more teeth than the older respondents. Although the univariate linear regression did not show a positive association between exposure to secondhand smoke and tooth loss, the multivariate-adjusted analysis revealed that respondents who were exposed to secondhand smoke at home almost every day had fewer teeth (β= -0.04; 95% CI: -0.07 – -0.01).

CONCLUSIONS

The present results suggest that exposure to secondhand smoke at home increases the risk of tooth loss.

Influence of Perceived Stress and Stress Coping Adequacy on Multiple Health-Related Lifestyle Behaviors

Stress is a primary target of national health promotion efforts such as Healthy Japan in the 21st century (HJ21). However, little is known about how the combination of perceived stress and coping adequacy influence health-related lifestyle behaviors in line with national health promotion. This study assessed the association between combined perceived stress and coping adequacy and multiple health-related lifestyle behaviors in HJ21 practices. This cross-sectional survey that included specialists in health management comprehensively assessed multiple health-related lifestyle behaviors in accordance with HJ21. Total health-related lifestyle behavior scores were calculated and perceived stress and coping adequacy were recorded and categorized into four groups with group 1 to 4 being high to none, and highly adequate to not at all, respectively. The average total lifestyle behavior scores (standard deviation [SD]) were 35.1 (3.5), 33.7 (3.6), 31.8 (3.8), and 30.5 (4.9) for groups 1 to 4 of coping adequacy (p < 0.001). Further, individuals who had higher stress coping adequacy had better multiple health-related lifestyle behaviors after adjusting for demographic factors and perceived stress in the linear trend among the groups. Stress coping skills might be an essential target for stress reduction, ultimately leading to health promotion for disease prevention and longevity.

Data-driven development of the Meal-based Diet History Questionnaire for Japanese adults

FFQ, the primary method of dietary assessment in large-scale nutritional epidemiological studies, preclude an informed evaluation of the timing of dietary intake and meal-specific dietary intake. In this study, we developed the Meal-based Diet History Questionnaire (MDHQ), a self-administered questionnaire designed for estimating food and nutrient intakes for each meal type separately. The development was done based on a 16-d dietary record obtained from 242 Japanese adults. The MDHQ consisted of the three different parts, with a total of 196 items. Part 1 of the MDHQ asks about consumption frequency of generic food groups (n 24) for each meal type: breakfast, morning snack, lunch, afternoon snack, dinner and night snack. Part 2 of the MDHQ asks about relative consumption frequency of sub-food groups within one of the generic food groups which are asked in Part 1. Combining information derived from Parts 1 and 2 enables us to increase the number of foods we can estimate efficiently but within a limited number of questions. Part 3 of the MDHQ asks about general eating behaviours, which are intended to use in a variety of ways during dietary intake calculation. A series of calculation algorithms for food groups, energy and nutrients was also prepared. Given that the MDHQ was empirically developed based on comprehensive information on actual food consumption, this innovative tool may be promising for future epidemiological research on meal patterns and time of day of dietary intake, or chrono-nutrition research. A rigorous evaluation of validity of the MDHQ is warranted.

Productivity burden of hypertension in Japan

In the present study, we aimed to estimate the impact of hypertension in the working-age Japanese population. We developed life table models to estimate total deaths, years of life lived, and productivity-adjusted life years lived (a newly developed metric for quantifying the burden of acute and chronic health conditions on work productivity) among Japanese individuals with hypertension aged 20-64 years, with simulated follow-up until age 65 years. Data inputs were drawn from local population statistics and published sources. Gross domestic product per person employed, a measure of labor productivity, was used to assign an economic value to each productivity-adjusted life year lived. Outcomes and costs were discounted by 2% annually. In 2017, 26.3 million Japanese individuals aged 20-64 years (37.5%) had hypertension. Of these people, 23.7% were treated and had controlled blood pressure, 23.2% were treated but had uncontrolled blood pressure, and 53.1% were untreated. During the simulated follow-up until age 65 years, 335,342 deaths (28.0% of total deaths), 1.6 million years of life (0.8% of total), 3.1 million productivity-adjusted life years (1.9% of total), and US$242.9 billion or 28.3 trillion Japanese yen of gross domestic product were lost to hypertension. Our findings highlight the considerable economic burden of hypertension in Japan, as well as the importance of effective strategies for hypertension prevention and management, which are likely to deliver a significant return on investment.

10-year trend of tooth loss and associated factors in a Japanese population-based longitudinal study

OBJECTIVES

We examined the trend in the number of missing teeth in a Japanese community over a 10-year period and the potential associated explanatory factors.

DESIGN

Prospective cohort study.

SETTING

A population-based study conducted in 2007, 2012 and 2017 in Japan (Hisayama Study).

PARTICIPANTS

Residents of a Japanese community aged 40-79 years undergoing dental examination in 2007 (n=2665), 2012 (n=2325) and 2017 (n=2285).

OUTCOME MEASURES

The number of missing teeth, periodontal condition, dental caries experience, dental plaque index and oral health behaviours were evaluated each year. The longitudinal analysis of variation in these factors were assessed using mixed models.

RESULTS

The age-adjusted and sex-adjusted mean number of missing teeth decreased with time (6.80 in 2007, 6.01 in 2012 and 4.99 in 2017). The mean clinical attachment level (CAL), prevalence of periodontitis and dental plaque index decreased over the study period, while dental caries experience slightly increased. The level of oral health behaviour increased over time. Poisson mixed models showed that changes in mean CAL and dental caries experience were positively associated with the change in the number of missing teeth over time. Linear mixed models showed that changes in dental plaque index and no regular dental visit were positively associated with changes in mean CAL.

CONCLUSIONS

These findings suggest that a decreasing trend regarding the number of missing teeth in Japan might be associated with improvements in the periodontal condition due to changes in oral hygiene level and oral health behaviour.

The Clustering of Health-Related Behaviors in the Adult Japanese Population

BACKGROUND

Research findings indicate that four health-related behaviors (HRBs), smoking, alcohol, diet, and physical activity, do not co-occur within individuals by chance and therefore cluster. To date, there is a lack of research investigating the clustering of these HRBs in the Japanese population.

METHODS

The Japanese National Health and Nutrition Survey 2010 was used, containing information on 8,015 community-dwelling adults. Latent profile analysis identified distinct cluster patterns of four HRBs: smoking status, alcohol consumption, calorie intake, and the number of steps per day.

RESULTS

For men, four distinct HRB clusters were identified. The largest cluster (54%) was characterized by drinking more than Japan's recommended alcohol guidelines and walking an inadequate number of steps per day. A small cluster (4%) also emerged, characterized by smoking, high calorie intake, and exceeding alcohol guidelines. Members of these clusters had higher systolic blood pressure than those in the remaining clusters. For women, five distinct HRB clusters were identified. The largest cluster (57%) was characterized by not smoking or drinking and walking an inadequate number of steps per day. For both genders, there was a relationship between cluster membership and age. Cluster membership was associated with income and health status among men but not women.

CONCLUSION

Detecting distinct clusters of HRBs in a Japanese population-based survey provides a person-centered understanding of Japanese lifestyles. This approach can assist policy makers in Japan and overseas to identify new strategies for targeting behavioral risk factors and make health promotion policies more effective in their respective countries.

Modifiable Risk Factors for Cardiovascular Disease in Korea and Japan

Cardiovascular disease (CVD) is the leading cause of death and a major contributor to disability worldwide. Since the majority of cardiovascular events are preventable, identification of modifiable CVD risk factors and implementation of primordial prevention strategies should be a public health priority. In this aspect, the American Heart Association declared a strategic goal to reduce total CVD mortality in the US by 20% within 10 years via eliminating 7 major CVD risk factors (hypertension, diabetes, dyslipidemia, cigarette smoking, physical inactivity, obesity, and poor-quality diet) in 2010, and their strategy has been achieving. However, the applicability of similar metrics to prevent CVD among East Asians requires an in-depth investigation of the modifiable CVD risk factors based on national and regional evidence-based findings. Herein, this review article aims to discuss several modifiable risk factors for CVDs, using epidemiological evidence from cohort studies and nationally representative data of 2 East Asian countries: Korea and Japan.

Prediction of disability-adjusted life years for diseases due to low fruit intake in 2017-2040 in Japan

OBJECTIVE

The current study aimed to predict disability-adjusted life years (DALY) rate in Japan through 2040 with plausible future scenarios of fruit intake for neoplasms, cardiovascular diseases (CVD) and diabetes and kidney diseases (DKD).

DESIGN

Data from National Health and Nutrition Surveys and the Global Burden of Diseases study in 2017 were used. We developed an autoregressive integrated moving average model with four future scenarios. Reference scenario maintains the current trend. Best scenario assumes that the goal defined in Health Japan 21 is achieved in 2023 and is kept constant afterwards. Moderate scenario assumes that the goal is achieved in 2040. Constant scenario applies the same proportion of 2016 for the period between 2017 and 2040.

SETTING

DALY rates in Japan were predicted for the period between 2017 and 2040.

PARTICIPANTS

Population aged more than than 20 years old.

RESULTS

In our reference forecast, the DALY rates in all-ages group were projected to be stable for CVD and continue increasing for neoplasms and DKD. Age group-specific DALY rates for these three disease groups were forecasted to decrease, with some exceptions. Among men aged 20-49 years, DALY attributable to CVD differed substantially between the scenarios, implying that there is a significant potential for reducing the burden of CVD by increasing fruit intake at the population level.

CONCLUSIONS

Our scenario analysis shows that higher fruit intake is associated with lower disease burden in Japan. Further research is required to assess which policies and interventions can be used to achieve an increase in fruit intake as modelled in the scenarios of the current study.

Association between free sugar intake and nutrient dilution among Japanese children and adolescents: the 2016 National Health and Nutrition Survey, Japan

The influence of free sugar intake on nutrient intake remains unclear in Japanese children and adolescents with relatively low free sugar intake. This cross-sectional study aimed to investigate the relationship between free sugar and selected nutrient intakes using data from the 2016 National Health and Nutrition Survey, Japan, based on the WHO recommendations (<5 % or <10 % of energy (%E)) for free sugar intake. A 1-d weighed dietary record was assessed in Japanese children and adolescents (aged 1-19 years; n 2919). Mean intakes for selected nutrients and food groups were compared according to free sugar intake categories (<2·5 %E, 2·5 to <5 %E, 5 to <10 %E and ≥10 %E) with adjustment for sex, age and weight status. Inverse associations were observed between intakes of free sugars and twenty-one of twenty-four micronutrients assessed, except for vitamins A and C and Ca. Significantly reduced intakes were identified for twenty-two and fourteen micronutrients in the ≥10 %E and 5 to <0 %E categories, respectively, compared with the lower categories. Mean micronutrient intakes at the <2·5 %E category did not differ from those at the 2·5 to <5 %E category. Free sugar intake had positive associations with intakes of sugars and jams, confectioneries, fruit and vegetable juices, and soft drinks and negative associations with intakes of pulses and nuts and vegetables. This study showed that nutrient dilution was associated with higher free sugar intake among Japanese children and adolescents. The findings suggest that the WHO recommendations might help prevent nutrient dilution in Japanese children and adolescents.

Prevalence and patterns of tobacco and/or nicotine product use in Japan (2017) after the launch of a heated tobacco product ( IQOS®): a cross-sectional study

Background: Several smoke-free tobacco and/or nicotine-containing products (TNP) have emerged in recent years to support tobacco harm reduction strategies and reduce individual health risks and population harm relative to continued cigarette smoking. This paper describes the nationwide prevalence and patterns of TNP use in Japan following the commercialization of one such smoke-free TNP, the heated tobacco product IQOS® (Philip Morris International).   Methods: We analyzed the first annual data (2016-2017) of two repeated cross-sectional surveys conducted in a representative sample of the Japanese general adult (≥20 years of age) population (N = 4,878) and a sample of adult IQOS users (N = 2,000). We assessed the prevalence of current TNP use according to type of product (cigarettes, IQOS, e-cigarettes, and other TNPs) in the general population and patterns of TNP use in the IQOS user sample. Results: The prevalence of current use across all TNP in the sampled general population was 18.5% (95% confidence interval 17.2-19.5%), with 17.5% (16.4-18.6%) for cigarette smoking and 1.8% (1.4-2.2%) for IQOS use. Regarding the distribution of patterns of use in the IQOS user survey, the majority (63.4% [61.2-65.6%]) were exclusive users of IQOS, followed by 20.6% (18.7-22.5%) of individuals who reported dual use of IQOS and cigarettes. Conclusions: In Japan, cigarette smoking remains the most prevalent way of consuming TNP; however, IQOS is being adopted by a growing number of adult Japanese smokers. These findings serve as baseline data for monitoring trends over time in the use and adoption of potential smoke-free TNP in Japan.

Prevalence and patterns of tobacco and/or nicotine product use in Japan (2017) after the launch of a heated tobacco product ( IQOS®): a cross-sectional study

Background: Several smoke-free tobacco and/or nicotine-containing products (TNP) have emerged in recent years to support tobacco harm reduction strategies and reduce individual health risks and population harm relative to continued cigarette smoking. This paper describes the nationwide prevalence and patterns of TNP use in Japan following the commercialization of one such smoke-free TNP, the heated tobacco product IQOS® (Philip Morris International).   Methods: We analyzed the first annual data (2016-2017) of two repeated cross-sectional surveys conducted in a representative sample of the Japanese general adult population (N = 4,878) and a sample of adult IQOS users (N = 2,000). We assessed the prevalence of current TNP use according to type of product (cigarettes, IQOS, e-cigarettes, and other TNPs) in the general population and patterns of TNP use in the IQOS user sample. Results: The prevalence of current use across all TNP in the general adult population was 18.5% (95% confidence interval 17.2-19.5%), with 17.5% (16.4-18.6%) for cigarette smoking and 1.8% (1.4-2.2%) for IQOS use. With regard to the distribution of patterns of use in the IQOS user survey, the majority (63.4% [61.2-65.6%]) were exclusive users of IQOS, followed by 20.6% (18.7-22.5%) of individuals who reported dual use of IQOS and cigarettes. Conclusions: In Japan, cigarette smoking remains the most prevalent way of consuming TNP; however, IQOS is being adopted by a growing number of adult Japanese smokers. These findings serve as baseline data for monitoring trends over time in the use and adoption of potential smoke-free TNP in Japan.

Evaluation of occlusal status of Japanese adults based on functional tooth units

OBJECTIVES

Although extensive national oral health data on dental caries and periodontal diseases in Japan are available, few studies have assessed the occlusal status of the Japanese population, and none are based on national survey data. The presence and prosthodontic conditions of the molar region are important for masticatory function, and the functional tooth unit (FTU) approach can be used to evaluate the occlusal status. Thus, using the national oral health survey data, this study investigated the occlusal status of the Japanese population using FTU.

METHODS

Overall, 3,605 adults (aged ≥20 years) who participated in the 2011 Japanese national oral health survey were included. FTUs were used as indices for evaluating the occlusal status. FTUs were calculated according to sex, age group, and the number of teeth present, and their associations were further analysed.

RESULTS

The number of teeth present, posterior teeth, and FTUs decreased with age in both men and women. In the age group of those ≥60 years, all only natural teeth-FTU (n-FTU) and natural teeth and artificial teeth from fixed prostheses or implant-supported FTU (nif-FTU) scores were <8. The total-FTU scores of all age groups, except the 60-69 and 70-79 years age groups, were >10.

CONCLUSION

This is the first study to use FTUs and national oral health survey data to investigate the occlusal status in the Japanese population. People aged ≥60 years who have low n-FTU or natural teeth and artificial teeth from fixed prostheses or implant-supported FTU scores or those aged 60-70 years who have the lowest total-FTU scores require careful evaluation of masticatory performance.