Association between visceral fat accumulation and decline in the estimated glomerular filtration rate based on cystatin C in the Japanese urban population: the KOBE study.

Although metabolic syndrome, including visceral fat accumulation, causes kidney and cardiovascular diseases, the impact of visceral fat accumulation on mild decreased renal function remains unclear. This study examines the association between visceral fat area (VFA) measured by bioimpedance methods and the estimated glomerular filtration rate based on serum cystatin C (eGFRcys) in the Japanese urban population. This community-based cross-sectional study enrolled 952 individuals (287 men, 665 women) who participated in the second follow-up survey of the Kobe Orthopedic and Biomedical Epidemiological (KOBE) study. We compared the multivariate-adjusted means of eGFRcys among VFA quartile groups by gender using the analysis of covariance. Models were adjusted for age, high blood pressure, hypercholesterolemia, glucose intolerance, smoking, and alcohol use, and further adjusted for body mass index (BMI). The highest VFA quartile group had lower eGFRcys than the lowest VFA quartile group after adjusted for cardiometabolic risk factors, except for BMI (93.1 [95% confidence interval (CI), 90.1-96.2] vs. 82.1 [95% CI, 79.1-85.0] in men and 95.8 [95% CI, 94.1-97.5] vs. 89.4 [95% CI, 87.8-90.9] in women). Moreover, further adjustment for BMI revealed a similar result in men (93.5 [95% CI, 89.8-97.2] vs. 81.6 [95% CI, 77.9-85.3]), while no significant association was found in women. This study suggests a significant association between increased VFA levels and lower eGFRcys levels independent of cardiometabolic risk factors, such as glucose intolerance and hypercholesterolemia in men and women, as well as independent of BMI in men.

Determinants of double product: a cross-sectional study of urban residents in Japan.

BACKGROUND: The current study aimed to investigate the determinants of high double product (DP) by evaluating the association between resting DP, which is calculated as systolic blood pressure (SBP) multiplied by heart rate (HR), and blood test results and lifestyle factors. METHODS: This research included 973 participants in the baseline survey of the KOBE study, which included a cohort of urban residents. The possible DP determinants were identified by examining the association between lifestyle factors and laboratory findings and DP by analyzing covariance adjusted for sex and age. Logistic regression analysis was performed with high DP (SBP × HR ≥ 9145 mmHg beats/min or quintile according to sex) as outcome and DP determinants as independent variables. RESULTS: Age, hematocrit, and gamma-glutamyl transferase (log) level were positively associated with a high DP in both men and women. In addition, a high DP was positively associated with Homeostatic Model Assessment for Insulin Resistance score in women alone. Meanwhile, the amount of exercise was negatively associated with a high DP in men alone. CONCLUSIONS: High DP values at rest were associated with insulin resistance, gamma-glutamyl transferase, and the amount of exercise in participants without underlying disease.

[Determinants of salt taste threshold among urban residents: the KOBE study].

Objectives　Though having a high salt taste threshold has been associated with hypertension, its exact determinants remains unclear. This study aimed to identify the determinants of salt taste threshold in a community-based population and to determine the relationship between salt taste thresholds and the simultaneous presence of multiple determinants.Methods　Of the 1,117 participants of the baseline survey of the Kobe study, a cohort study of healthy urban residents, aged 40-74 years, with no history of cancer or cardiovascular diseases, nor undergoing treatment for hypertension, diabetes, or dyslipidemia, was conducted. Among them, 1,116 underwent the salt taste threshold test, and urine samples were collected to determine their estimated salt intake. The salt taste threshold test was carried out using SALSAVE®, with a salt taste threshold of 0.6% defined as normal, and that of 0.8% or more defined as high. A binomial logistic regression model was used, with high salt taste threshold as the objective variable, and life and family status, education, smoking and alcohol drinking status, intake status of salt dried fish, stress indicators, and daily salt intake (estimated from the urine sample) as the explanatory variables. A binomial logistic regression analysis was conducted, through multivariate analysis using the forced entry method, with factors influencing salt taste threshold as explanatory variables, and salt taste threshold (normal/high) as the objective variable. This analysis was performed excluding the urinary sodium-to-potassium ratio to account for multicollinearity with the estimated daily salt intake.Results　The mean age was 60.9±9.0 years for men, and 58.0±8.7 years for women. The salt taste threshold was normal in 80.9% (n=903) of the participants (73.6% [n=251] men and 84.1% [n=652] women), and high in 19.1% (n=213) of the participants (26.3% [n=90] men and 15.9% [n=123] women). Multivariate analysis revealed that smoking habits were significantly associated with a higher salt taste threshold, with an odds ratio (95% confidence interval) of 2.51 (1.33-4.74) for all participants. The odds ratio for a high salt taste threshold was 1.45 (1.03-2.03) for the top 25% estimated daily salt intake group, showing a significant association with a high salt taste threshold. In the analysis by sex, smoking habits were associated with higher salt taste thresholds, while an association with estimated daily salt intake was observed only in men.Conclusion　Smoking status and estimated daily salt intake were associated with higher salt taste thresholds in healthy urban residents.

Relationship of urinary liver-type fatty acid-binding protein with cardiovascular risk factors in the Japanese population without chronic kidney disease: Sasayama study.

BACKGROUND: Urinary liver-type fatty acid-binding protein (L-FABP) is a well-known marker of proximal tubular impairment. We evaluated the relationship between cardiovascular disease (CVD) risk factors and levels of L-FABP in a cross-sectional community-based study. Participants with normoalbuminuria and normal estimated glomerular filtration rate (eGFR), that is, non-chronic kidney disease (non-CKD), were enrolled in this study. To the best of our knowledge, this is the first study to focus on the association between CVD risk factors and a proximal tubular marker in the Japanese general population with normoalbuminuria and normal eGFR. METHODS: The present study is part of the Sasayama study. The participants included 1000 community residents (447 men and 553 women) aged 40-64 years without a history of CVD or renal dysfunction. Out of these participants 375 men and 477 women, defined as non-CKD, were included for further analysis. In each sex, the highest quintile group was considered to have high-normal L-FABP levels. A multiple logistic regression model was used to evaluate the relationship between risk factors for CVD and high-normal L-FABP levels in the non-CKD participants. We performed a similar analysis using the high-normal urinary albumin to creatinine ratio (UACR) as a dependent variable instead of L-FABP. RESULTS: Among the non-CKD participants, in the highest quintile group (Q5, top 20%), L-FABP was ≥2.17 µg/gCre in men and ≥ 2.83 µg/gCre in women. In women, the multivariate odds ratio was 3.62 (1.45-9.00) for high-normal L-FABP in the presence of diabetes mellitus (DM) compared with that in the group without DM. However, the relationship between DM and the UACR level was not significant. In men, DM was significantly associated with high-normal UACR. However, the relationship with L-FABP levels was not significant. CONCLUSIONS: The presence of DM was more strongly related to high-normal L-FABP levels than to high-normal UACR in women even at the stage of normoalbuminuria and normal eGFR. Our results were also consistent with the findings of a previous study where women were more prone to nonalbuminuric renal impairment compared to men, although further studies are required to confirm the results.

[Association of the combined estimated 24-h urinary Na/K ratio and body mass index with blood pressure: Cross-sectional data from the KOBE study].

Objective　Several studies have suggested that high dietary Na/K ratio and body mass index (BMI) increase the prevalence of hypertension. However, there have been a few reports on the combination of these two factors and their relationship with hypertension. This study aimed to examine the association of the combined estimated 24-h urinary Na/K ratio (24h-u-Na/K) (high or low) and BMI (high or low) with the risk of high blood pressure.Method　We performed a cross-sectional study involving 1,112 participants (340 men and 772 women) of the Kobe Orthopedic and Biomedical Epidemiological study (KOBE study) who had no cardiovascular diseases or current anti-hypertensive medications. Sex-specific analyses were performed. The 24h-u-Na/K ratio was calculated from an estimation formula using collected spot urine. Participants were divided into four groups based on their 24h-u-Na/K ratio (low or high) and BMI (low or high), with the cutoff points being the median and 25 kg/m2, respectively.　Participants with systolic blood pressure (SBP) ≥130 mmHg or diastolic blood pressure (DBP) ≥80 mmHg were diagnosed with high blood pressure. Odds ratios (ORs) for high blood pressure according to the combined risks of high 24h-u-Na/K and BMI were examined with a logistic regression analysis.Results　The average SBP/DBP for men and women was 122.7/77.9 and 113.3/69.1 mmHg, respectively, and prevalence of high blood pressure among men and women was 47.4% and 21.3%, respectively. The mean BMI was 22.8 kg/m2 for men and 20.9 kg/m2 for women. The median 24h-u-Na/K was 3.2 for men and 3.1 for women. The prevalence of high blood pressure (men, women) was the highest in the group in which both 24h-u-Na/K and BMI were high (60.0%, 62.9%; men: P=0.273; women: P<0.001). In the same group, the multivariate-adjusted ORs for high blood pressure were significantly higher for both men (2.59; 95% confidence interval [CI]: 1.15-5.86) and women (10.78; 95% CI: 4.87-23.88) compared to the reference group with both factors classified as low. Women with low BMI but high 24h-u-Na/K also demonstrated a higher risk for high blood pressure (OR: 1.62; 95% CI: 1.10-2.40).Conclusion　The risk of high blood pressure was the highest when both BMI and 24h-u-Na/K were high. The current specific healthcare guidance in Japan is focused on obese individuals. However, in order to prevent hypertension more effectively, additional focus should be placed on the Na/K diet. Increased intake of vegetables and fruits and reduced intake of salt should be strongly recommended.

[The search for a predictor of deterioration of the nonspecific stress index K6 among urban residents: The KOBE study].

Objective　To explore health-related and socioeconomic factors that can predict future deterioration in Psychological Distress Scale (K6) scores.Method　We conducted a baseline (2010, 2011) self-administered questionnaire survey of the Kobe Orthopedic and Biomedical Epidemiological study (KOBE study) involving 1,117 participants who had no previous history of cancer or cardiovascular diseases and were not under treatment for hypertension, diabetes, or dyslipidemia. We used the Japanese K6 as an indicator of stress and defined K6≧5 points as a high-stress group and K6<5 points as a low-stress group. A four-year follow-up survey (2014, 2015) was conducted on 1,004 people (follow-up rate of 90%). We excluded 39 participants with missing values, and 185 people whose K6 score was higher than 5 points at baseline. A final total of 780 participants' scores were examined for: gender, age, living situation, physical activity level, average sleep time, as well as the K6 score, the Japanese Hearing Handicap Inventory for Elderly (HHIE-S), and the Japanese Oswestry Disability Index (ODI). We conducted a logistic regression analysis using K6≧5 points at the four-year follow-up survey as the dependent variable and each factor at the baseline survey as the independent variable.Results　Of the 780 subjects analyzed, 132 (16.9%) were highly stressed (K6≧5 points) at the four-year follow-up point. A logistic regression analysis found age (40s/70s) (odds ratio 3.38, 95% confidence interval 1.45-7.86), living situation (single/living together) (odds ratio 1.98, 95% confidence interval 1.07-3.68), and ODI scores (every 1%) (odds ratio 1.05, 95% confidence interval 1.01-1.09), to all be significantly associated with high stress.Conclusion　This study suggests that age, living situation, and ODI scores are related to future stress.

Daily Habit of Water Intake in Patients with Cerebral Infarction before its Onset; Comparison with a Healthy Population: A Cross-Sectional Study.

BACKGROUND: While water intake is frequently recommended to prevent cerebral infarction (CI), only few studies have been published on this topic. OBJECTIVES: This study retrospectively estimated the daily non-alcohol drink (NAD) intake in CI patients before CI onset and compared it with NAD in healthy subjects. METHODS: We performed a cross-sectional study on CI patients in 3 hospitals and healthy subjects in the Kobe Orthopedic and Biomedical Epidemiologic (KOBE) study. Data from 1,287 subjects (274 CI patients and 1,013 healthy subjects) were used for the analyses. By dividing the CI patients into "increased", "unchanged", and "decreased" groups according to their current NAD intake, we compared the NAD intake between these 3 groups and healthy subjects by analyses of covariance and the post hoc test, adjusting for sex, age, surveyed month, body mass index, alcohol drinking history, and smoking history. Under the assumption that the NAD intake in the "unchanged" group was equal to the NAD intake before CI onset, the OR of less NAD intake for CI adjusting for the relevant variables in the "unchanged" group and the healthy subjects was calculated; the cut-off point was chosen using Youden's index. RESULTS: The mean age (mean ± SD) of the participants was 62.8 ± 9.3 years. One hundred and fifty-one patients (36 women) were included in the "increased" group; 105 (30 women), in the "unchanged" group; 18 (2 women), in the "decreased" group; and 1,013 (706 women), in the "healthy" group. The mean NAD intake was 1,702.5 ± 670.2 mL in the "increased" group, 1,494.2 ± 611.2 mL in the "unchanged" group, 1,268.0 ± 596.1 mL in the "decreased" group, and 1,720.6 ± 686.0 mL in the "healthy" group. After adjusting for the relevant variables, a significant difference in NAD intake between the groups was observed (F = 6.1, p < 0.001), and a post hoc test demonstrated significant differences (p < 0.05) in NAD intake between the "healthy" and "unchanged" groups, and between the "increased" and "unchanged" groups. The OR of less NAD intake (<1,570 mL/day, chosen using Youden's index) for CI was 2.48 (95% CI 1.52-4.07). CONCLUSION: This study showed that daily NAD intake before CI onset in CI patients was less than that in healthy persons, indicating that sufficient intake of NAD may be protective for CI.

Higher serum uric acid level is inversely associated with renal function assessed by cystatin C in a Japanese general population without chronic kidney disease: the KOBE study.

BACKGROUND: Although several epidemiological studies have suggested that high serum uric acid (SUA) levels are related to a decline in kidney function, only a few studies have investigated using cystatin C to calculate estimated glomerular filtration rate (eGFR). We aimed to clarify the relationship between SUA levels and kidney function assessed by cystatin C in a Japanese general community population without chronic kidney disease (CKD). METHODS: We conducted a community-based cross-sectional study that included 1086 healthy participants, aged 40-74 years, without CKD and not undergoing treatment of hyperuricemia, who had participated in the baseline survey of the Kobe Orthopedic and Biomedical Epidemiological (KOBE) study. The preconditions for participation in this study were no past histories of cardiovascular disease or cancer, and not undergoing treatment for diabetes, hypertension, or dyslipidemia. We classified the participants into quartiles stratified by sex according to their SUA level and then examined the relationship with eGFR. The odds ratios for having a low eGFR, defined as the lowest quartile of eGFR (i.e., ≤78.4 mL/min/1. 73m2) was estimated according to SUA quartiles (men, Q1 ≤ 5.0, Q2 5.1-5.9, Q3 6.0-6.6, and Q4 ≥ 6.7; women, Q1 ≤ 3.8, Q2 3.9-4.3, Q3 4.4-4.9, and Q4 ≥ 5.0 mg/dL) after adjustment for age, body mass index, systolic blood pressure, HbA1c, high and low density lipoprotein cholesterol, and smoking and drinking habits. The adjusted mean of each quartile was also calculated. RESULTS: Multivariable-adjusted means of eGFR showed a graded decrease in higher SUA quartiles (men, Q1 90.5, Q2 88.0, Q3 83.5, and Q4 82.0; women, Q1 95.7, Q2 91.3, Q3 89.2, and Q4 86.7). In addition, the multivariable-adjusted odds ratios for having a lower eGFR (95% confidence interval) for each SUA quartile compared with Q1 was Q2 2.29 (0.98, 5.35), Q3 4.94 (2.04, 11.97), and Q4 8.01 (3.20, 20.04) for men, and was Q2 2.20 (1.12, 4.32), Q3 2.68 (1.39, 5.20), and Q4 4.96 (2.62, 9.41) for women. CONCLUSIONS: There was a graded inverse relationship between mild elevations in SUA levels and eGFR assessed by cystatin C in an apparently healthy Japanese population without CKD. This association was similar in both men and women.

Underweight Young Women Without Later Weight Gain Are at High Risk for Osteopenia After Midlife: The KOBE Study.

BACKGROUND: Although underweight young women are targets for interventions to prevent low bone mineral density (BMD), the relationship between change in body mass index (BMI) from youth to older age and BMD has not been widely investigated in community dwellers. METHODS: In 749 healthy Japanese women aged 40-74 years, BMD was measured by quantitative ultrasound and anthropometric measurements, and BMI was calculated from body weight and height. The BMI of participants at age 20 years was estimated by self-reported body weight and their present height. They were classified into four groups according to the presence of underweight (BMI <18.5 kg/m2) at 20 and/or at present. Logistic regression models were used to estimate multivariate-adjusted odds ratios (ORs) of the presence of underweight at 20 and/or at present for osteopenia (BMD T score <-1 standard deviations) compared with participants with BMI ≥18.5 kg/m2 both at 20 and at present. RESULTS: The participants who were underweight both at 20 and at present had a higher OR for osteopenia compared with those with BMI ≥18.5 kg/m2 at 20 and at present (OR 3.94; 95% confidence interval [CI], 1.97-7.89). Those underweight only at present also had significantly increased OR of developing osteopenia (OR 2.95; 95% CI, 1.67-5.24). The OR of those underweight only at 20 was 0.87 (95% CI, 0.51-1.48). CONCLUSIONS: Current underweight was associated with increased risk for osteopenia among Japanese women, especially in those who were underweight both at 20 and at present. To prevent low BMD in the future, maintaining appropriate body weight might be effective for young underweight women.

Impact of Flushing Response on the Relationship between Alcohol Consumption and Gamma-glutamyl Transpeptidase: the KOBE study.

Individuals with an inactive acetaldehyde dehydrogenase 2 have an. elevated level of serum acetaldehyde after drinking alcohol, and this may cause an alcohol flushing response with symptoms such as facial flushing, tachycardia, headache, and nausea. Recent studies have suggested that the flushing response influences the association between alcohol consumption and various health-related outcomes. In the present study, we investigated the impact of the flushing response on the relationship between alcohol consumption and serum y -GTP levels in Japanese drinkers. We conducted a cross-sectional study of 521 Japanese drinkers (260 men and 261 'vomen) to examine the impact of the alcohol flushing response on the relationship between alcohol consumption and serum y -GTP levels. The subjects were divided into three groups according to the amount .of daily alcohol consumption. (low, <20 g; moderate, 20-39 g;. and high, >40 g). Multiple adjustments were performed with linear regression models to examine the association between daily alcohol consumption and serum y-GTP levels, adjusting for potential con- founders including the flushing response. We found that the proportion of flushers was significantly lower in the high alcohol consumption group than in the low consumption group. The results of a multivariable analysis showed that,serum y -GTP levels were significantly higher in the moderate and high consumption groups than in the low consumption group after. adjusting for all potential confounders other than the flushing response. In addition, the association between serum y -GTP levels and alcohol consumption was unchanged after adjusting for the presence of the flushing response. In conclusion, serum y -GTP levels increased with increasing alcohol-consumption regardless of the flushing response. Screening for heavy drinkers using serum y-GTP levels was very important to prevent alcohol-related diseases or health problems in health examination.

Association between serum long-chain n-3 and n-6 polyunsaturated fatty acid profiles and glomerular filtration rate assessed by serum creatinine and cystatin C levels in Japanese community-dwellers.

BACKGROUND: Plasma concentration of n-3 polyunsaturated fatty acids (PUFAs) has been reported to be associated with renal function in Western populations. However, few studies have investigated the association between serum long-chain n-3 and n-6 PUFA profiles and renal function in a Japanese population with high marine-derived long-chain n-3 PUFA intake. METHODS: A cross-sectional study was performed in 549 Japanese rural community-dwellers aged 40 to 64 years. In adjusted analysis of covariance, we assessed the relationship between estimated glomerular filtration rate (eGFR) and tertiles of serum long-chain n-3 and n-6 PUFA profiles ([eicosapentaenoic acid {EPA} + docosahexaenoic acid {DHA}]:arachidonic acid [AA]). GFR was estimated by Japanese specific equations using serum creatinine and cystatin C (eGFRcre and eGFRcys). Using multivariate-adjusted linear regression models, we also assessed the relationships between eGFRs and several n-3 and n-6 PUFAs, which have been suggested to be associated with renal function. RESULTS: In all participants, higher dietary fish intake as assessed by a semi-quantitative questionnaire was associated with higher serum value of (EPA+DHA):AA. Participants in the higher (EPA+DHA):AA tertiles had non-significantly higher eGFRcre and significantly higher eGFRcys (P = 0.016). In addition, eGFRcys in T2+T3 of (EPA+DHA):AA was significantly higher than that in T1 (adjusted mean eGFRcys, T1: 87 ml/min/1.73 m(2), T2+T3: 91 ml/min/1.73 m(2); P < 0.01). Among the PUFAs, only (EPA+DHA) was significantly associated with eGFRcys. CONCLUSIONS: Serum (EPA+DHA):AA, which reflects an individual's fish intake, might be associated with eGFRcys in Japanese community-dwellers.

HOMA-IR Values are Associated With Glycemic Control in Japanese Subjects Without Diabetes or Obesity: The KOBE Study.

BACKGROUND: Several studies have reported that insulin resistance was a major risk factor for the onset of type 2 diabetes mellitus in individuals without diabetes or obesity. We aimed to clarify the association between insulin resistance and glycemic control in Japanese subjects without diabetes or obesity. METHODS: We conducted a community-based cross-sectional study including 1083 healthy subjects (323 men and 760 women) in an urban area. We performed multivariate regression analyses to estimate the association between the homeostasis model assessment of insulin resistance (HOMA-IR) values and markers of glycemic control, including glycated haemoglobin (HbA1c), 1,5-anhydroglucitol (1,5-AG), and fasting plasma glucose (FPG) levels, after adjustment for potential confounders. RESULTS: Compared with the lowest tertile of HOMA-IR values, the highest tertile was significantly associated with HbA1c and FPG levels after adjustment for potential confounders, both in men (HbA1c: ß = 1.83, P = 0.001; FPG: ß = 0.49, P < 0.001) and women (HbA1c: ß = 0.82, P = 0.008; FPG: ß = 0.39, P < 0.001). The highest tertile of HOMA-IR values was inversely associated with 1,5-AG levels compared with the lowest tertile (ß = -18.42, P = 0.009) only in men. CONCLUSIONS: HOMA-IR values were associated with markers of glycemic control in Japanese subjects without diabetes or obesity. Insulin resistance may influence glycemic control even in a lean, non-diabetic Asian population.

Physique at Birth and Cardiovascular Disease Risk Factors in Japanese Urban Residents: the KOBE Study.

AIM: This study investigated the relationship between birth physique and cardiovascular risk factors in Japanese urban residents aged 40 years and more. METHODS: A self-administered questionnaire on birth physique was performed among 624 individuals (165 men and 459 women) who participated in the KOBE study. We examined whether self-reported birth physique and available recorded birth weights matched for 72 participants. Then the association between birth physique and risk factors for all participants was examined by gender. Body size at birth in the questionnaire (large, medium, small) was set as an exposure and laboratory values from the baseline survey (2010-2011) were used as outcomes. RESULTS: Mean (standard deviation) recorded birth weight of 72 participants was 3665 (318), 3051 (300), and 2653 (199) g, in the large, medium, and small group, respectively. In the analysis for all participants, odds ratio for having both hypertension and impaired glucose tolerance were significantly higher in the small versus large birth weight group, which was 7.42 (95% CI 1.75-31.50) for men and 4.44 (95% CI 1.14-17.30) for women after adjusting for age, body mass index, smoking/alcohol/exercise habits, and menstrual status in women. Similar results were observed in participants with recorded birth weight. CONCLUSIONS: The present study indicates that individuals with small physique at birth might be at higher risk for hypertension and impaired glucose tolerance in middle age compared to those with large birth weight.

Dietary intakes of antioxidant vitamins and mortality from cardiovascular disease: the Japan Collaborative Cohort Study (JACC) study.

BACKGROUND AND PURPOSE: Only a few reports have dealt with the association of antioxidant vitamin intakes with mortality or morbidity from cardiovascular disease in Asia. We investigated the relation of dietary vitamins A, E, and C intake with mortality from cardiovascular disease for Japanese men and women. METHODS: The subjects were 23,119 men and 35 611 women aged 40 to 79 years without a history of cardiovascular disease or cancer who responded to the food frequency questionnaire as part of the Japan Collaborative Cohort Study for Cancer Risk (JACC) Study. They were followed up for a median period of 16.5 years. Hazard ratios were calculated per quintile of dietary vitamins A, E, and C intake by using Cox proportional hazard model. RESULTS: During the 859,962 person-year follow-up, there were 2690 deaths (1343 men and 1347 women) from cardiovascular disease, comprising 1227 (607 men and 620 women) from stroke and 557 (311 men and 246 women) from coronary heart disease. The multivariable hazard ratios (95% CI) associated with the highest versus lowest quintiles of vitamin C intake were 0.70 (0.54 to 0.92) for total stroke, 0.63 (0.41 to 0.97) for coronary heart disease, and 0.79 (0.66 to 0.94) for total cardiovascular disease for women, but the inverse associations observed were weak and did not reach statistical significance for men. No significant association was observed between vitamins A or E intake and risk of mortality for either men or women. CONCLUSIONS: Vitamin C intake is inversely associated with mortality from cardiovascular disease for Japanese women.

Paleoceanography of the northwestern Pacific across the Early-Middle Pleistocene boundary (Marine Isotope Stages 20-18).

The fluctuating position of the boundary between the Kuroshio (warm) and Oyashio (cold) currents in the mid-latitude western North Pacific affects both heat transport and air-ocean interactions and has significant consequences for the East Asian climate. We reconstruct the paleoceanography of Marine Isotope Stages (MIS) 20-18, MIS 19 being one of the closest astronomical analogues to the present interglacial, through multiple proxies including microfossil assemblage data, planktonic foraminiferal isotopes (δ18O and δ13C), and foraminiferal Mg/Ca-based temperature records, from the Chiba composite section (CbCS) exposed on the Boso Peninsula, east-central Japan. Principal component analysis (PCA) is used to capture dominant patterns of the temporal variation in these marine records, and shows that the relative abundances of calcareous nannofossil and radiolarian taxa are consistent with the water mass types inferred from geochemical proxies. The leading mode (36.3% of total variance) mirrors variation in the terrestrial East Asian winter monsoon (EAWM), reflecting seasonal trends dominated by the winter monsoon system. In the CbCS, this mode is interpreted as reflecting the interplay between the warm Kuroshio and cold Oyashio waters, which is likely related to the latitudinal shift of the subtropical-subarctic gyre boundary in the North Pacific. The second mode (15.4% of total variance) is closely related to subsurface conditions. The leading mode indicates that MIS 19b and 19a are represented by millennial-scale stadial/interstadial oscillations. Northerly positions for the gyre boundary during late MIS 19c, the interstadials of MIS 19a, and early MIS 18 are inferred from the leading mode, which is consistent with a weak EAWM and consequent mild winter climate in East Asia. Nonetheless, the northerly positions for the gyre boundary during late MIS 19c and early MIS 19a were not associated with subsurface warming presumably due to the suppressed gyre circulation itself caused by the weak Aleutian Low. Intermittent southerly positions for the gyre boundary are inferred for the stadials of MIS 19b and 19a. Regional sea surface temperature (SST) comparisons in the western North Pacific reveal that the moderate SSTs during MIS 19a through early MIS 18 were restricted to the mid- to high latitudes, influenced by the weak EAWM. Comparison between MIS 20-18 and MIS 2-1 suggests that glacial MIS 20 and 18 had significantly milder winters than MIS 2, likely related to the relatively weak EAWM. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40645-020-00395-3.

Roles of insolation forcing and CO2 forcing on Late Pleistocene seasonal sea surface temperatures.

Late Pleistocene changes in insolation, greenhouse gas concentrations, and ice sheets have different spatially and seasonally modulated climatic fingerprints. By exploring the seasonality of paleoclimate proxy data, we gain deeper insight into the drivers of climate changes. Here, we investigate changes in alkenone-based annual mean and Globigerinoides ruber Mg/Ca-based summer sea surface temperatures in the East China Sea and their linkages to climate forcing over the past 400,000 years. During interglacial-glacial cycles, there are phase differences between annual mean and seasonal (summer and winter) temperatures, which relate to seasonal insolation changes. These phase differences are most evident during interglacials. During glacial terminations, temperature changes were strongly affected by CO2. Early temperature minima, ~20,000 years before glacial terminations, except the last glacial period, coincide with the largest temperature differences between summer and winter, and with the timing of the lowest atmospheric CO2 concentration. These findings imply the need to consider proxy seasonality and seasonal climate variability to estimate climate sensitivity.

Palaeolithic voyage for invisible islands beyond the horizon.

How Palaeolithic maritime transportation originated and developed is one of the key questions to understand the world-wide dispersal of modern humans that began 70,000-50,000 years ago. However, although the earliest evidence of maritime migration to Sahul (Australia and New Guinea) has been intensively studied, succeeding development of Paleolithic maritime activity is poorly understood. Here, we show evidence of deliberate crossing of challenging ocean that occurred 35,000-30,000 years ago in another region of the western Pacific, the Ryukyu Islands of southwestern Japan. Our analysis of satellite-tracked buoys drifting in the actual ocean demonstrated that accidental drift does not explain maritime migration to this 1200 km-long chain of islands, where the local ocean flows have kept the same since the late Pleistocene. Migration to the Ryukyus is difficult because it requires navigation across one of the world's strongest current, the Kuroshio, toward an island that lay invisible beyond the horizon. This suggests that the Palaeolithic island colonization occurred in a wide area of the western Pacific was a result of human's active and continued exploration, backed up by technological advancement.

Estimated 24 h Urinary Sodium-to-Potassium Ratio Is Related to Renal Function Decline: A 6-Year Cohort Study of Japanese Urban Residents.

The effect of the sodium-to-potassium ratio (Na/K) on renal function within the clinically normal range of renal function are limited. We investigated the effects of an estimated 24 h urinary Na/K (e24hUNa/K) on a 6-year renal function decline among 927 urban Japanese community dwellers with no history of cardiovascular diseases and medication for hypertension, diabetes, or dyslipidemia. We partitioned the subjects into quartiles according to the e24hUNa/K. The estimated glomerular filtration rate (eGFR) was calculated using the chronic kidney disease epidemiology collaboration (CKD/EPI) formula and renal function decline was defined as an absolute value at or above the third quartile of the eGFR decline rate. A multivariable logistic regression model was used for estimation. Compared with the first quartile of the e24hUNa/K, multivariable-adjusted odds ratios (ORs) for eGFR decline in the second, third, and fourth quartiles were 0.96 (95% confidence interval: 0.61-1.51), 1.06 (0.67-1.66), and 1.65 (1.06-2.57), respectively. These results were similar when the simple spot urine Na/K ratio was used in place of the e24hUNa/K. Apparently healthy urban residents with an almost within normal range mean baseline eGFR and high e24hUNa/K ratios had an increased risk for a future decline in renal function. Reducing the Na/K ratio may be important in the prevention of chronic kidney disease in its early stage.

The reproducibility of 24-h dietary recall for estimating mineral intakes and their food sources among middle-aged Japanese men and women.

The objective of the present study was to examine reproducibility for mineral intakes estimated by single 24-h dietary recall for middle-aged Japanese men and women. We conducted repeated cross-sectional study between 1973 and 1999. The subjects were 262 Japanese people (132 men and 130 women) aged 40-69 years. The median Spearman correlation coefficients (range) for mineral intakes were 0.43 (0.31-0.55) for men and 0.39 (0.32-0.50) for women. The correlation coefficients stratified by the survey periods 1973-1984 and 1985-1999 were 0.42 (0.31-0.53) for men and 0.44 (0.34-0.53) for women during the earlier period, and 0.43 (0.22-0.62) for men and 0.29 (0.21-0.65) for women during the later period. In conclusion, the reproducibility of single 24-h dietary recall was fairly good for estimating mineral intakes by middle-aged Japanese men and women, although the reproducibility for some minerals tended to decline from the mid-1980s.