Development and preliminary validation of a prediction formula of sodium and sodium-to-potassium ratio based on multiple regression using 24-h urines.

Accurate measurement of sodium intake in the diet is challenging, and epidemiological studies can be hampered by the attenuation of associations due to measurement error in sodium intake. A prediction formula for habitual 24-h urine sodium excretion and sodium-to-potassium ratio might lead to more reliable conclusions. Five 24-h urinary samples and two Food Frequency Questionnaires (FFQs) were conducted among 244 Japanese participants aged 35-80 years. We conducted multivariate linear regression analysis with urinary excretion as dependent variables and eating behaviour and food frequency as independent variables. Empirical weights of sodium excretion and sodium-to-potassium ratio were extracted. Preliminary validity was also assessed by randomly dividing the subjects into development and validation groups based on the correlation coefficient between estimates by the prediction formula and urinary excretion. Taste preference, soy sauce use at the table, frequency of pickled vegetables intake and number of bowls of miso soup were extracted as determinants of sodium excretion. Correlation coefficients between the estimates and urinary excretion for men and women were 0.42 and 0.43, respectively, for sodium and 0.49 and 0.50, respectively, for sodium-to-potassium ratio. This prediction formula may provide more accurate estimation of sodium intake and sodium-to-potassium ratio than the food composition approach.

Urinary Biomarkers in Screening for the Usual Intake of Fruit and Vegetables, and Sodium, Potassium, and the Sodium-to-Potassium Ratio: Required Number and Accuracy of Measurements.

Because of within-individual variation, surveys to estimate an individual's usual food intake must be conducted over many days, in general. Here, using non-invasive biomarkers, we examined the number of measurements required to screen for the usual intake of fruit and vegetables, in addition to sodium, potassium, and the sodium-to-potassium (Na/K) ratio. Participants were 202 subjects aged 40-74 years from five areas of Japan who completed weighed food records (WFR) and five 24-hour urinary collections (24-h UCs) between 2012 and 2013. The number of 24-h UCs required to screen for intake that deviated from guidelines estimated by the WFR and their accuracies were assessed by the area under the curve (AUC) in a receiver-operating characteristics (ROC) analysis. The single urinary excretion of sodium, potassium, and the Na/K ratio showed moderate performance (AUC value: >0.7) in discriminating deviations from their criteria by respective intake based on the WFR. Urinary potassium excretion also showed moderate performance (AUC value: >0.7) in estimating the intake of vegetables but could not be used to estimate fruit intake even after five collections. The non-invasive measurement of biomarkers in a single 24-h UC showed moderate performance in screening the usual intake of vegetables, as measured based on the 12-day WFR, as well as of sodium, potassium, and the Na/K ratio.

Validity of the intake of sugars, amino acids, and fatty acids estimated using a self-administered food frequency questionnaire in middle-aged and elderly Japanese: the Japan Public Health Center-based Prospective Study for the Next Generation (JPHC-NEXT) Protocol Area.

BACKGROUND: The Japanese database of food composition was revised in 2020, during which both the number of food items and the number of food items measured for sugars, amino acids, and fatty acids were increased. We evaluated the validity of estimated intakes of sugars, amino acids and fatty acids using a long-food frequency questionnaire (FFQ) among middle-aged and elderly Japanese. METHODS: From 2012 to 2013, 240 men and women aged 40-74 years from five areas in the JPHC-NEXT protocol were asked to respond to the long-FFQ and provide a 12-day weighed food record (WFR) as reference. The long-FFQ, which included 172 food and beverage items and 11 seasonings, was compared with a 3-day WFR, completed during each distinct season, and validity was assessed using Spearman's correlation coefficients. RESULTS: Percentage differences based on the long-FFQ with the 12-day WFR in men and women varied from -83.9% to 419.6%, and from -75.8% to 623.1% for sugars, -17.5% to 2.8% and -5.8% to 19.6% for amino acids, and -58.5% to 78.8% and -43.4% to 129.3% for fatty acids, respectively. Median values of correlation coefficients for the long-FFQ in men and women were 0.52 and 0.42 for sugars, 0.38 and 0.37 for amino acids, and 0.42 and 0.42 for fatty acids, respectively. CONCLUSIONS: The long-FFQ provided reasonable validity in estimating the intakes of sugars, amino acids, and fatty acids in middle-aged and elderly Japanese. Although caution is warranted for some nutrients, these results may be used in future epidemiological studies.

Association between dry eye and periodontal disease in community-dwelling Japanese adults: data from the Uonoma cohort study.

BACKGROUND: While research has explored the risk of periodontal disease in various eye conditions, the link between dry eye and periodontal disease remains underexplored, especially in Japanese adults. This study aims to investigate the association between dry eye and periodontal disease in community-dwelling Japanese adults. METHODS: This study is a subset of the Uonuma cohort study, which includes Japanese adults aged 40 years and older residing in the Uonuma area of Niigata Prefecture, Japan. Participants completed a self-administered, paper-based questionnaire. Statistical analyses, including the chi-square test, independent t test, ANOVA test, and logistic regressions, were employed to assess the association of periodontal disease with independent variables. RESULTS: Among 36,488 participants (average age 63.3 years, 47.4% men), 39.3% had a history of periodontal disease, and gender differences were statistically significant (p < 0.001). Significant associations were found between periodontal disease and dry eye diagnosis or symptoms. Univariable logistic regression revealed links between periodontal disease and age, gender, living status, alcohol consumption, remaining teeth, bite molar availability, and history of dry eye disease or symptoms. Multiple-adjusted regression found that doctor-diagnosed dry eye was associated with a higher likelihood of periodontal disease (odds ratio, 1.12; 95% confidence interval, 1.03-1.22). Participants who never experienced dryness or foreign body sensation had lower ORs of periodontal disease than those who always experienced such symptoms across all models. CONCLUSION: A significant correlation was found between dry eye and periodontal disease in Japanese adults. Regular check-ups, early detection, and effective management of both conditions are strongly recommended.

Reproducibility and dietary correlates of plasma polyphenols in the JPHC-NEXT Protocol Area study.

BACKGROUND: In recent years, an increasing number of epidemiological studies have suggested a role of polyphenols in the prevention of chronic diseases. Prospective cohort studies have typically measured polyphenol concentrations in a single blood sample and the reproducibility of plasma polyphenol measurements is largely unknown. OBJECTIVE: We evaluated the reproducibility of 35 plasma polyphenols collected at an interval of 1-year. We also examined correlations of these polyphenols with food group intakes calculated from weighed food records (WFR) and food frequency questionnaire (FFQ). METHODS: The study included 227 middle-aged participants from the JPHC-NEXT Protocol Area in Japan. We measured 35 polyphenols in plasma collected at two points 1-year apart. Food group intakes were calculated from 12-day WFR and FFQ. For the reproducibility analysis, the intraclass correlation coefficient (ICC) of 35 polyphenol concentrations were examined between the two points. Pearson's partial correlations was used to assess the correlation between polyphenols and food groups. RESULTS: Moderate- to high ICCs were observed for tea-originated polyphenols such as gallic acid, quercetin, epigallocatechin, and kaempferol - and coffee-derived polyphenols, such as caffeic acid, and ferulic acid. For the dietary analyses, moderate correlations were observed for non-alcoholic beverages intake and epigallocatechin, epicatechin, catechin, and gallic acid. For green tea, higher correlations were observed with these polyphenols. CONCLUSION: Plasma concentrations of tea and coffee-related polyphenols, except for catechin, had good reproducibility over a 1-year period. The correlations between intake of non-alcoholic beverages, particularly green tea, and tea polyphenols, indicated moderate- to high correlations.

Association between Physical Activity in Rural Life and Sarcopenia in Community-Dwelling Middle-Aged and Older Japanese Adults: A Cross-Sectional Study.

Physical activity is crucial to prevent sarcopenia, but there is scant data on the link between sarcopenia and physical activity in rural communities. Therefore, this study investigated associations of farming activity and snow removal with sarcopenia in a middle-aged and older population in rural Japan. This cross-sectional study enrolled 3,056 residents aged ≥ 40 years (49.2% men; mean age, 64.2 years) in Yuzawa, Japan. Information on farming activity and snow removal were collected via questionnaire from May through November and from December through April, respectively. Sarcopenia was assessed by the SARC-F (strength, ambulation, rising from a chair, stair climbing, and history of falling) score. Associations of farming activity and snow removal with sarcopenia were assessed using multivariable logistic regression analysis with adjustment for potential confounders. Participants who engaged in farming activity, snow removal, and both accounted for 3.8%, 40.5%, and 29.4% of the total, respectively. In the multivariable logistic regression analysis, adjusted odds ratios [95% confidence intervals (CI)] of sarcopenia for farming activity and snow removal were 0.80 (0.63-1.03) and 0.68 (0.53-0.87), respectively. Compared with participants who did not engage in farming activity or snow removal, participants who engaged in both had a significantly lower adjusted odds ratio of sarcopenia [0.63 (95% CI 0.47-0.86)]. Participants who engaged in snow removal and those who engaged in both farming activity and snow removal showed inverse associations with sarcopenia. Our findings further support the importance of physical activity in preventing or mitigating sarcopenia in rural communities.

Associations between Plasma Antibody Levels against Porphyromonas gingivalis and Atrial Fibrillation among Community-Dwelling Older Individuals in Japan: A Cross-Sectional Study.

PURPOSE: To investigate the association between plasma antibody levels against Porphyromonas gingivalis (PG) and atrial fibrillation (AF) history in community-dwelling older individuals in Japan. MATERIALS AND METHODS: This study was a subset of the Uonuma cohort study, including 3091 participants aged 60-79 years. Data were collected, including AF history as a dependent variable, plasma immunoglobulin G antibody levels against PG as an independent variable, and previously reported AF risk factors and demographic information as covariates. RESULTS: The median age of the participants was 69 years. Of the 3091 participants, 1411 (45.6%) were men, and 56 (1.8%) had an AF history. AF prevalence was significantly higher in participants with higher antibody levels against PG than in those with lower antibody levels (3.0% vs 1.4%; p = 0.005). Multivariable logistic regression analysis showed that participants with higher antibody levels against PG had twofold higher odds of having AF (odds ratio = 2.13; 95% confidence interval = 1.23-3.69). Restricted cubic spline analysis indicated a nonlinear relationship between antibody levels against PG and AF history. CONCLUSION: Plasma antibody levels against PG were associated with AF history in community-dwelling older individuals in Japan.

Chronic kidney disease awareness and its determinants in middle-aged and older Japanese adults: Observations from a 5-year follow-up of the Uonuma cohort study.

AIM: Despite global efforts in public health campaigns concerning chronic kidney disease (CKD), awareness of the condition remains low. We evaluated CKD awareness and related factors to identify an effective way to raise awareness. METHODS: This study assessed laboratory-confirmed CKD and self-reported CKD using a population-based cohort (baseline from 2012 to 2014, age ≥40 years) in Niigata, Japan. Self-reported CKD was obtained at a 5-year follow-up survey and laboratory-confirmed CKD was diagnosed when an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 or dipstick urinary protein ≥1+ was observed in at least two health check-ups during the 5-year period. CKD awareness was defined as a match between laboratory-confirmed and self-reported CKD. The association between characteristics and CKD awareness was tested by multivariable logistic regression analysis with adjustment for eGFR and other potential confounders. RESULTS: The analytic population comprised 7472 individuals (mean age, 65.6 years old, 51.2% women) and 19.4% with laboratory-confirmed CKD. The sensitivity and specificity of the survey question concerning self-reported CKD were 12.4% and 98.2%, respectively. Among the participants with laboratory-confirmed CKD, significant factors associated with CKD awareness were male sex (adjusted odds ratio [95% confidence interval], 1.81 [1.27, 2.59]), a history of urinary tract stone (1.86 [1.06, 3.26]), age (0.97 [0.95, 0.99]), and married status (0.66 [0.44, 0.99]). CONCLUSION: Our findings suggest that known lifestyle-related diseases that could cause CKD are not associated with CKD awareness independently of kidney function and that a sex-dependent approach may help to raise CKD awareness in community-dwelling Japanese adults.

Applicability of a Web-based 24-hour Dietary Recall Tool for Japanese Populations in Large-scale Epidemiological Studies.

BACKGROUND: Recent innovations in information and communication technology have made it possible to assess diet using web-based methods; however, their applicability in the general population remains unclear. Hence, we aimed to examine the applicability of a web-based 24-hour dietary recall (24HR) tool to large-scale epidemiological studies by determining the sampling rate and characteristics of randomly selected participants from a Japanese cohort study. METHODS: In total, 5,013 individuals were recruited from a cohort of 21,537 individuals, and 975 agreed to participate in this study. The participants selected either self-administered web-based dietary 24HR (self-administered 24HR) or interviewer-administered telephone-based 24HR (interviewer-administered 24HR) as the method for the dietary assessment and answered questions regarding the acceptability of the system. RESULTS: The response rate of the 975 participants was 19.4%, corresponding to approximately 4.5% of the total study sample. About half of them chose the self-administered 24HR (46.9%). The median time required for the self-administered and interviewer-administered 24HR was 25 and 27 minutes, respectively. In the self-administered 24HR, older people, regardless of sex, tended to require a longer time, and approximately 60% of the participants rated the ease of use of the system as "somewhat difficult" or "difficult." CONCLUSION: Characteristics of the participants in this study were not systemically different from those of the entire study sample. Improvements in the approach to entering cooking details and the dish name selection may be necessary for better acceptability in order to be accepted as a self-administered dietary recall tool.

Dietary sodium sources according to four 3-d weighed food records and their association with multiple 24-h urinary excretions among middle-aged and elderly Japanese participants in rural areas.

Reducing Na intake is an urgent global challenge, especially in East Asia and high-income Asia-Pacific regions. However, the sources of Na and their effects on urinary Na excretion have not been fully studied. We sought to clarify these sources and their association with urinary Na excretion. We examined four 3-d weighed food records and five 24-h urinary collections from each of 253 participants in Japan, aged 35-80 years, between 2012 and 2013. We compared the levels of Na according to four categories: foods contributing to discretionary or non-discretionary Na intake, the situation in which dishes were cooked and consumed, food groups and types of cuisine. We also conducted regression analysis in which 24-h urinary Na excretion was a dependent variable and the amounts of food intake in the four categories were independent variables. Levels of Na were the highest in discretionary intake (60·6 %) and in home-prepared dishes (84·0 %). Of the food groups, miso soup showed the highest percentage contribution to Na intake (13·3 %) after seasonings such as soya sauce. In the regression analysis, the standardised coefficient for foods of non-discretionary Na sources was larger than that for discretionary sources, whereas that for home-prepared dishes was consistent with the levels of Na in those foods. Pickled products, followed by fresh fish and shellfish, miso soup and rice, were associated with high urinary Na excretion. Thus, discretionary foods (such as miso soup) contribute the most to Na consumption, although non-discretionary intake (such as pickled vegetables) may influence urinary Na excretion.

Associations of Urinary and Dietary Sodium-To-Potassium Ratios with Albuminuria in Community-Dwelling Japanese Adults: A Cross-Sectional Study.

INTRODUCTION: The urinary sodium-to-potassium ratio is an indicator of dietary sodium intake and has been associated with reduced kidney function. However, less is known about its association with albuminuria, the other key component of chronic kidney disease, in the community-dwelling adult population. We examined the association of the spot urinary sodium-to-potassium ratio with albuminuria and compared spot urinary and dietary sodium-to-potassium ratios. METHODS: We quantified the association of the urinary sodium-to-potassium ratio with albuminuria in 6,274 Japanese adults (aged 40-97 years; 50.9% women) based on spot urine samples. We performed linear and logistic regression modeling to account for potential confounders. Elevated albuminuria was defined as a spot urinary albumin-to-creatinine ratio (ACR) ≥30 mg/g. We secondarily evaluated the dietary sodium-to-potassium ratio based on a food-frequency questionnaire. RESULTS: The median spot urinary and dietary sodium-to-potassium ratios were 2.70 (interquartile interval, 1.87-3.83) and 1.50 (1.21-1.84), respectively. The median ACR was 11.0 (6.0-24.0) mg/g. In a multivariable linear regression model, the spot urinary sodium-to-potassium ratio (per increment) was significantly associated with the natural logarithm of the ACR (regression coefficient, 0.023 [95% confidence interval {95% CI}, 0.007-0.038]). This result was consistent in a multivariable logistic regression model (adjusted odds ratio, 1.08 [95% CI: 1.04-1.12]). The corresponding estimates for the dietary sodium-to-potassium ratio were 0.139 (95% CI: 0.087-0.191) and 1.28 (95% CI: 1.14-1.45), respectively. CONCLUSIONS: Both spot urinary and dietary sodium-to-potassium ratios were associated with elevated albuminuria in community-dwelling Japanese adults. Our findings further support the potential usefulness of the spot urinary sodium-to-potassium ratio as an indicator of sodium intake and suggest a link between sodium intake and kidney damage.

Validity of the Food Frequency Questionnaire-Estimated Intakes of Sodium, Potassium, and Sodium-to-Potassium Ratio for Screening at a Point of Absolute Intake among Middle-Aged and Older Japanese Adults.

Using Food Frequency Questionnaires (FFQs) to compare dietary references for screening has been in high demand. However, FFQs have been widely used for ranking individuals in a population based on their dietary intake. We determined the validity of sodium (salt equivalent) intake, potassium intake, and sodium-to-potassium (Na/K) ratio obtained using the FFQ for identifying individuals who deviated from the dietary reference intakes (DRIs) measured using multiple 24-h urinary excretion measurements or 12-day weighed food records (WFR). This study included 235 middle-aged subjects. The correlation coefficients (CCs) between the FFQ and WFR estimates were mostly moderate (0.24−0.54); the CCs between the FFQ and 24-h urinary excretion measurements were low or moderate (0.26−0.38). Values of area under the receiver-operating curve (AUC) at the point of DRIs for salt equivalent or potassium were >0.7 with the WFR as the reference standard and 0.60−0.76 with the 24-h urinary excretion as the reference standard. Using both standard measures, the AUC for the Na/K ratio was <0.7. The accuracy of salt equivalent and potassium intake estimation using the FFQ to determine absolute intake point was comparable to that using WFR, allowing for quantified error, but not as good as that of 24-h urinary excretion.

Association between Sarcopenia and Depressive Symptoms in Community-Dwelling People Aged 40 Years and Older.

Several studies have reported an association between sarcopenia and depression. Their results, however, are inconsistent, partly due to small sample sizes and lack of consideration of important confounders. The present study aimed to cross-sectionally examine this association in community-dwelling people in Japan. This study used baseline data from the Yuzawa cohort study (age ≥ 40 years), with the final analysis population comprising 2,466 participants. A self-administered questionnaire was used to elicit information related to sarcopenia, depressive symptoms, demographic characteristics, anthropometrics, disease history, and lifestyles. Sarcopenia was diagnosed using SARC-F, a validated questionnaire including components of Strength, Assistance in walking, Rising from a chair, Climbing stairs, and Falls. Depressive symptoms were assessed using the 11-item version of the Center for Epidemiologic Studies Depression Scale (CES-D). For depressive symptoms, prevalence ratios (PRs) were calculated, and odds ratio (ORs) were obtained using simple and multiple logistic regression analyses. Mean age of participants was 61.7 years (standard deviation = 11.8), and 10.5% and 34.7% had sarcopenia and depressive symptoms, respectively. Sarcopenic individuals had a significantly higher PR (2.00), unadjusted OR (3.67), and adjusted OR (4.96) compared to non-sarcopenic individuals, with an estimated adjusted PR of 2.7. There was a significant dose-dependent association between SARC-F scores and depressive symptoms in sarcopenic individuals (adjusted P for trend = 0.0028). In conclusion, sarcopenia and depressive symptoms were robustly associated in community-dwelling, middle-aged and older people in Japan. However, the direction of this association is unclear, and a future cohort study will be needed to determine causality.

Association of metabolic syndrome traits with urinary biomarkers in Japanese adults.

BACKGROUND: Although metabolic syndrome traits are risk factors for chronic kidney disease, few studies have examined their association with urinary biomarkers. METHODS: Urinary biomarkers, including A-megalin, C-megalin, podocalyxin, albumin, α1-microglobulin, ß2-microglobulin, and N-acetyl-ß-D-glucosaminidase, were cross-sectionally assessed in 347 individuals (52.7% men) with a urine albumin-to-creatinine ratio (ACR) < 300 mg/g in a health checkup. Metabolic syndrome traits were adopted from the National Cholesterol Education Program (third revision) of the Adult Treatment Panel criteria modified for Asians. RESULTS: Participants had a mean body mass index, estimated glomerular filtration rate (eGFR), and median ACR of 23.0 kg/m2, 74.8 mL/min/1.73 m2, and 7.5 mg/g, respectively. In age- and sex-adjusted logistic regression analysis, A-megalin and albumin were significantly associated with the clustering number of metabolic syndrome traits (3 or more). After further adjustment with eGFR, higher quartiles of A-megalin and albumin were each independently associated with the clustering number of metabolic syndrome traits (adjusted odds ratio for A-megalin: 1.30 per quartile, 95% CI 1.03-1.64; albumin: 1.42 per quartile, 95% CI 1.12-1.79). CONCLUSIONS: Both urinary A-megalin and albumin are associated with the clustering number of metabolic syndrome traits. Further research on urinary A-megalin is warranted to examine its role as a potential marker of kidney damage from metabolic risk factors.

Validity of dietary isothiocyanate intake estimates from a food frequency questionnaire using 24 h urinary isothiocyanate excretion as an objective biomarker: the JPHC-NEXT protocol area.

BACKGROUND/OBJECTIVES: Isothiocyanate (ITC) is formed via the hydrolysis of glucosinolates by myrosinase, found in cruciferous vegetables. Although myrosinase is inactivated by the cooking process, no studies have incorporated the effect of cooking into the estimation of dietary ITC intake or evaluated the validity. We evaluated the validity of dietary ITC intake estimated from a food frequency questionnaire (FFQ), and urinary ITC levels using 24 h urine samples or a WFR (weighed food record), and evaluated the reproducibility of dietary ITC in two FFQs administered at an interval of 1-year. SUBJECTS/METHODS: The JPHC-NEXT Protocol Area included a total of 255 middle-aged participants across Japan. We calculated dietary ITC intake from WFR and two FFQs by assuming that cooked cruciferous vegetables contain zero ITC. Urinary ITC excretion was measured at two points during summer and winter. The validity and reproducibility of dietary ITC intake estimated by FFQ were assessed using Spearman's correlation coefficients. RESULTS: Although we observed a moderate correlation between dietary ITC intake derived from a 12-day WFR and urinary ITC excretion, notwithstanding the cooking process, the correlation between dietary ITC intake estimated by FFQ and mean urinary ITC excretion was low. However, the correlation was improved when we compared urinary ITC excretion and a 3-day WFR or FFQ collected during winter. Our FFQ showed good reproducibility. CONCLUSION: Although seasonality is a critical factor, dietary ITC intake estimated using an FFQ showed moderate validity and reproducibility and can be used in future epidemiological studies.

Education, household income, and depressive symptoms in middle-aged and older Japanese adults.

BACKGROUND: Income inequality has dramatically increased worldwide, and there is a need to re-evaluate the association between socio-economic status (SES) and depression. Relative contributions of household income and education to depression, as well as their interactions, have not been fully evaluated. This study aimed to examine the association between SES and depressive symptoms in Japanese adults, focusing on interactions between education and household income levels. METHODS: This cross-sectional study used data from baseline surveys of two cohort studies. Participants were 38,499 community-dwelling people aged 40-74 years who participated in baseline surveys of the Murakami cohort study (2011-2012) and Uonuma cohort study (2012-2015) conducted in Niigata Prefecture, Japan. Information regarding marital status, education level, household income, occupation, activities of daily living (ADL), and history of cancer, myocardial infarction, stroke, and diabetes was obtained using a self-administered questionnaire. Depressive symptoms were examined using the Center for Epidemiologic Studies Depression Scale (CES-D). Logistic regression analysis was used to obtain odds ratios (ORs). Covariates included age, sex, marital status, education, household income, occupation, ADL, and disease history. RESULTS: Individuals with higher education levels had lower ORs (adjusted P for trend = 0.0007) for depressive symptoms, independently of household income level. The OR of the university-or-higher group was significantly lower than that of the junior high school group (adjusted OR = 0.79). Individuals with lower household income levels had higher ORs (adjusted P for trend< 0.0001) for depressive symptoms, independently of education level. The type of occupation was not associated with depressive symptoms. In subgroup analyses according to household income level, individuals with higher education levels had significantly lower ORs in the lowest- and lower-income groups (adjusted P for trend = 0.0275 and 0.0123, respectively), but not in higher- and highest-income groups (0.5214 and 0.0915, respectively). CONCLUSIONS: Both education and household income levels are independently associated with the prevalence of depressive symptoms, with household income levels showing a more robust association with depressive symptoms than education levels. This suggests that a high household income level may offset the risk of depressive symptoms from having a low education level.

Determination of specific life changes on psychological distress during the COVID-19 pandemic.

The COVID-19 pandemic might affect many aspects of the community and a range of psychiatric risk factors due to life changes, including people's behaviors and perceptions. In this study, we aim to identify specific life changes that correlate with psychological distress within the social context of the COVID-19 pandemic in Japan. In July 2020, workers (company employees and civil servants) in Japan were recruited from local institutions that had not had any confirmed COVID-19 cases as well as neighborhoods that had only a few cases. Participants completed a COVID-19 mental health survey (N = 609; 66.9% male). Psychological distress was identified based on Kessler-6 scores (≥13). Life changes were assessed by an open-ended question about life changes in participants and their family, workplace, and community due to the COVID-19 pandemic. A convergent mixed-method approach was used to compare the context of perceived life changes in participants with psychological distress and those without. As a result, 8.9% of participants had psychological distress, and sex and age categories were different between those with psychological distress and those without. Among the participants who responded to the open-ended question, the biggest life change was "staying at home," and the next biggest life changes were "event cancellations" and "increased workload" in participants with psychological distress, and "no changes" and "mask-wearing" in those without psychological distress, respectively. Regarding emotional/perceptual changes, "stress," "fear," and "anger" were more frequently reported by participants with psychological distress than those without (P <0.001). By integrating these findings, we identified themes focusing on vulnerable characteristics related to psychological distress. This study may provide a source in society for mediating psychological distress during a pandemic.

Association Between Estimated Glomerular Filtration Rate Based on Cystatin C and Grip Strength in Community-Dwelling Japanese Older Adults.

BACKGROUND: Kidney dysfunction is associated with sarcopenia. Estimated glomerular filtration rate based on cystatin C (eGFRcys), an alternative to creatinine-based measures of kidney function eGFR, is not affected by muscle mass. Given that the association of eGFRcys with muscle weakness would be limited, we examined the association in older adults with normal or compromised kidney function. METHODS: This cross-sectional study involved 594 community-dwelling Japanese adults aged ≥40 years living in Yuzawa, Japan. Serum creatinine, cystatin C, and handgrip strength were concurrently measured at a health-check examination in 2015. eGFR was calculated according to the equation developed for the Japanese population using creatinine and cystatin C. Associations of eGFRcys and eGFRcreat with low grip strength (men, <26 kg and women, <18 kg) were analyzed using logistic regression models adjusted to control for potential confounders. RESULTS: Participants (mean age, 74.9 years) included 319 women and 109 individuals with low grip strength. Mean eGFRcys was 75.2 (SD 18.6) mL/min/1.73 m2. Pearson's correlation coefficients of handgrip strength for eGFRcys and eGFRcreat were 0.19 (p < .001) and -0.04 (p = .281), respectively. Multivariate logistic regression analysis showed the adjusted odds ratio (OR) of low grip strength for the highest versus lowest quartile of eGFRcys value was 2.46 (95% confidence interval, 1.03-5.86; p-trend = .026); whereas the comparative adjusted OR for eGFRcreat was 0.67 (95% confidence interval, 0.34-1.32). CONCLUSIONS: Low kidney function as assessed by eGFRcys was associated with muscle weakness in community-dwelling Japanese older adults.

Variations in the estimated intake of acrylamide from food in the Japanese population.

BACKGROUND: Due to concerns of carcinogenicity, it is necessary to assess long-term acrylamide exposure in individuals. Whether the available methods of estimating acrylamide intake can indicate long-term exposure remains unknown. We examined variations in the estimated dietary acrylamide intake of the Japanese population. METHODS: The study included 240 participants aged 40-74 years who were a part of the Japan Public Health Center-based Prospective Study for the Next Generation (JPHC-NEXT). Twelve-day dietary records (DRs) were collected over a one-year period, and food frequency questionnaires (FFQs) were collected twice during the year. Dietary acrylamide intake was estimated from an acrylamide content database. Within-individual variations and between-individual variations were calculated using the random effects model. A linear regression analysis was performed to identify foods with large between-individual variations. RESULTS: The ratios of within-individual variance to between-individual variation were 3.2 for men and 4.3 for women. Days of DRs required to estimate the usual individual intake within 20% of the true mean intake with 95% confidence were 60 days for men and 66 days for women. Coffee/cocoa, potato, and green tea contributed to between-individual variations, in that order, and seven foods contributed to 93% of the between-individual variation. CONCLUSIONS: Estimating the acrylamide intake using DRs requires an extended data collection period to estimate the intragroup ranking and habitual intake of individuals. Long-term exposure assessments should be based on methods with less potential for measurement errors, such as the use of biomarkers.

Low serum 25-hydroxyvitamin D is associated with low grip strength in an older Japanese population.

Positive associations between vitamin D levels and hand grip strength have been reported worldwide, but the results are not consistent and few studies on East Asian populations have been published. The aim of this study was to determine whether such an association is present in a community-dwelling Japanese population, including elderly and middle-aged individuals. This study used a cross-sectional design. Participants were 492 community-dwelling individuals aged ≥ 40 years living in Yuzawa Town, Japan. The health check examination was conducted in 2015, and serum 25-hydroxyvitamin D [25(OH)D, an index of vitamin D levels], and hand grip strength were measured. Covariates were serum albumin concentration, body mass index, and physical activity level. The associations of serum 25(OH)D concentrations with hand grip strength and low grip strength (< 26 kg for men and < 18 kg for women) were analyzed using analysis of covariance and multiple logistic regression. Mean (standard deviation) age and serum 25(OH)D were 75.4 (9.0) years and 30.9 (9.1) ng/mL, respectively. The prevalence of serum 25(OH)D < 20, 20-29, and ≥ 30 ng/mL was 7.3%, 37.8%, and 54.9%, respectively. Mean hand grip strength in the 25(OH)D < 20 ng/mL group was significantly lower than that in the ≥ 30 ng/mL group (adjusted P ≤ 0.001). The 25(OH)D < 20 ng/mL group was significantly more likely to have low grip strength than the 25(OH)D ≥ 30 ng/mL group (odds ratio = 4.12). In conclusion, low serum 25(OH)D concentration (< 20 ng/mL) is associated with low grip strength in an older Japanese population.