Comparison of risk factors for SARS-CoV-2 infection among healthcare workers during Omicron and Delta dominance periods in Japan.

BACKGROUND: The risk factors for coronavirus disease (COVID-19) among healthcare workers (HCWs) might have changed since the emergence of the highly immune evasive Omicron variant. AIM: To compare the risk factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among HCWs during the Delta- and Omicron-predominant periods. METHODS: Using data from repeated serosurveys among the staff of a medical research centre in Tokyo, two cohorts were established: Delta period cohort (N = 858) and Omicron period cohort (N = 652). The potential risk factors were assessed using a questionnaire. Acute/current or past SARS-CoV-2 infection was identified by polymerase chain reaction or anti-nucleocapsid antibody tests, respectively. Poisson regression was used to calculate the risk ratio (RR) of infection risk. FINDINGS: The risk of SARS-CoV-2 infection during the early Omicron-predominant period was 3.4-fold higher than during the Delta-predominant period. Neither working in a COVID-19-related department nor having a higher degree of occupational exposure to SARS-CoV-2 was associated with an increased infection risk during both periods. During the Omicron-predominant period, infection risk was higher among those who spent ≥30 min in closed spaces, crowded spaces, and close-contact settings without wearing mask (≥3 times versus never: RR: 6.62; 95% confidence interval: 3.01-14.58), whereas no such association was found during the Delta period. CONCLUSION: Occupational exposure to COVID-19-related work was not associated with the risk of SARS-CoV-2 infection in the Delta or Omicron period, whereas high-risk behaviours were associated with an increased infection risk during the Omicron period.

Cigarette smoking and cervical cancer risk: an evaluation based on a systematic review and meta-analysis among Japanese women.

BACKGROUND: There is a body of evidence to suggest that cigarette smoking increases the risk of cervical cancer in women, but no study has examined the magnitude of the association in Japanese women. Here, we evaluated the association between cigarette smoking and the risk of cervical cancer in Japanese women based on a systematic review of epidemiological evidence. METHODS: Original data were obtained from a MEDLINE search using PubMed or from a search of the 'Ichushi' database, as well as by a manual search. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as evaluated previously by the International Agency for Research on Cancer. Meta-analysis of associations was also conducted to obtain a summarized overview of the data. RESULTS: We identified two cohort studies and three case-control studies. All five studies had indicated strong positive associations between cigarette smoking and the risk of cervical cancer. Our summary estimate indicated that the relative risk (RR) for individuals who had ever-smoked relative to never-smokers was 2.03 (95% confidence interval: 1.49-2.57). Four studies had also demonstrated dose-response relationships between cigarette smoking and the risk of cervical cancer. CONCLUSION: We conclude that there is convincing evidence that cigarette smoking increases the risk of cervical cancer among Japanese women.

Evidence-based cancer prevention recommendations for Japanese.

A comprehensive evidence-based cancer prevention recommendation for Japanese was developed. We evaluated the magnitude of the associations of lifestyle factors and infection with cancer through a systematic review of the literature, meta-analysis of published data, and pooled analysis of cohort studies in Japan. Then, we judged the strength of evidence based on the consistency of the associations between exposure and cancer and biological plausibility. Important factors were extracted and summarized as an evidence-based, current cancer prevention recommendation: 'Cancer Prevention Recommendation for Japanese'. The recommendation addresses six important domains related to exposure and cancer, including smoking, alcohol drinking, diet, physical activity, body weight and infection. The next step should focus on the development of effective behavior modification programs and their implementation and dissemination.

Predictive performance of a genetic risk score using 11 susceptibility alleles for the incidence of Type 2 diabetes in a general Japanese population: a nested case-control study.

AIMS: To assess the predictive ability of a genetic risk score for the incidence of Type 2 diabetes in a general Japanese population. METHODS: This prospective case-control study, nested within a Japan Public Health Centre-based prospective study, included 466 participants with incident Type 2 diabetes over a 5-year period (cases) and 1361 control participants, as well as 1463 participants with existing diabetes and 1463 control participants. Eleven susceptibility single nucleotide polymorphisms, identified through genome-wide association studies and replicated in Japanese populations, were analysed. RESULTS: Most single nucleotide polymorphism loci showed directionally consistent associations with diabetes. From the combined samples, one single nucleotide polymorphism (rs2206734 at CDKAL1) reached a genome-wide significance level (odds ratio 1.28, 95% CI 1.18-1.40; P = 1.8 × 10-8 ). Three single nucleotide polymorphisms (rs2206734 in CDKAL1, rs2383208 in CDKN2A/B, and rs2237892 in KCNQ1) were nominally significantly associated with incident diabetes. Compared with the lowest quintile of the total number of risk alleles, the highest quintile had a higher odds of incident diabetes (odds ratio 2.34, 95% CI 1.59-3.46) after adjusting for conventional risk factors such as age, sex and BMI. The addition to the conventional risk factor-based model of a genetic risk score using the 11 single nucleotide polymorphisms significantly improved predictive performance; the c-statistic increased by 0.021, net reclassification improved by 6.2%, and integrated discrimination improved by 0.003. CONCLUSIONS: Our prospective findings suggest that the addition of a genetic risk score may provide modest but significant incremental predictive performance beyond that of the conventional risk factor-based model without biochemical markers.

Risk of haemolytic uraemic syndrome caused by shiga-toxin-producing Escherichia coli infection in adult women in Japan.

Shiga-toxin-producing Escherichia coli (STEC) infections usually cause haemolytic uraemic syndrome (HUS) equally in male and female children. This study investigated the localization of globotriaosylceramide (Gb3) in human brain and kidney tissues removed from forensic autopsy cases in Japan. A fatal case was used as a positive control in an outbreak of diarrhoeal disease caused by STEC O157:H7 in a kindergarten in Urawa in 1990. Positive immunodetection of Gb3 was significantly more frequent in female than in male distal and collecting renal tubules. To correlate this finding with a clinical outcome, a retrospective analysis of the predictors of renal failure in the 162 patients of two outbreaks in Japan was performed: one in Tochigi in 2002 and the other in Kagawa Prefecture in 2005. This study concludes renal failure, including HUS, was significantly associated with female sex, and the odds ratio was 4·06 compared to male patients in the two outbreaks. From 2006 to 2009 in Japan, the risk factor of HUS associated with STEC infection was analysed. The number of males and females and the proportion of females who developed HUS were calculated by age and year from 2006 to 2009. In 2006, 2007 and 2009 in adults aged >20 years, adult women were significantly more at risk of developing HUS in Japan.

Association of adulthood weight gain with circulating adipokine and insulin resistance in the Japanese population.

BACKGROUND/OBJECTIVES: Although adipokines and insulin resistance are known to be correlated with body fatness, it is unclear whether they are independently related to weight gain experience. We examined the associations of serum adipokines and marker of insulin resistance with past weight gain during adulthood by taking the degree of attained body mass index (BMI) level into consideration. SUBJECTS/METHODS: Subjects were 399 Japanese municipal employees, aged ⩾ 30 years, who participated in a health survey. Serum adipokines were measured using a Luminex suspension bead-based multiplexed array. Weight change during adulthood was calculated as the difference between measured current weight and recalled weight at the age of 20 years. Multiple regression was performed to calculate mean adipokine levels and homeostasis model assessment of insulin resistance (HOMA-IR) according to weight gain (< 5 kg, 5-9.9 kg, or ⩾ 10 kg) with adjustment for current BMI. RESULTS: Weight gain from the age of 20 years was significantly and positively associated with leptin levels even after adjustment for current BMI (P for trend < 0.001), whereas it was significantly and inversely associated with adiponectin levels in a BMI-adjusted model among subjects aged ⩾ 40 years (P for trend=0.03). Weight gain was associated with HOMA-IR in a BMI-unadjusted model (P for trend < 0.001), but this association was largely attenuated after adjustment for BMI. Resistin, plasminogen activator inhibitor-1 and visfatin were not associated with past weight gain. CONCLUSIONS: Results suggest that a large weight gain during adulthood is associated with higher leptin and lower adiponectin levels independently of the degree of attained BMI level.

Circulating adiponectin levels and risk of type 2 diabetes in the Japanese.

BACKGROUND: Adiponectin has anti-inflammatory and insulin-sensitizing properties. Prospective studies have consistently shown a lower risk of type 2 diabetes among those with higher circulating adiponectin levels. OBJECTIVE: We examined prospectively the association between serum adiponectin levels and type 2 diabetes risk among Japanese workers, taking visceral fat mass into account. SUBJECTS AND METHODS: Subjects were 4591 Japanese employees who attended a comprehensive health screening in 2008; had biochemical data including serum adiponectin; were free of diabetes at baseline; and received health screening in 2011. Multiple logistic regression analysis was used to examine the association between adiponectin and incidence of diabetes among overall subjects, as well as subgroups. Stratified analyses were carried out according to variables including visceral fat area (VFA). RESULTS: During 3 years of follow-up, 217 diabetic cases were newly identified. Of these, 87% had a prediabetes at baseline. Serum adiponectin level was significantly, inversely associated with incidence of diabetes, with odds ratios (95% confidence interval) adjusted for age, sex, family history, smoking, alcohol drinking, physical activity and body mass index (BMI) for the lowest through highest quartile of adiponectin of 1 (reference), 0.79 (0.55-1.12), 0.60 (0.41-0.88) and 0.40 (0.25-0.64), respectively (P-value for trend <0.01). This association was materially unchanged with adjustment for VFA instead of BMI. After further adjustment for both homeostasis model assessment of insulin resistance and hemoglobin A1c, however, the association became statistically nonsignificant (P-value for trend=0.18). Risk reduction associated with higher adiponectin levels was observed in both participants with and without obesity or insulin resistance at baseline. CONCLUSIONS: RESULTS suggest that higher levels of circulating adiponectin are associated with a lower risk of type 2 diabetes, independently of overall and intra-abdominal fat deposition, and that adiponectin may confer a benefit in both persons with and without insulin resistance.

Association of vegetable and fruit intake with gastric cancer risk among Japanese: a pooled analysis of four cohort studies.

BACKGROUND: Prospective evidence is inconsistent regarding the association between vegetable/fruit intake and the risk of gastric cancer. METHODS: In an analysis of original data from four population-based prospective cohort studies encompassing 191 232 participants, we used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of gastric cancer incidence according to vegetable and fruit intake and conducted a meta-analysis of HRs derived from each study. RESULTS: During 2 094 428 person-years of follow-up, 2995 gastric cancer cases were identified. After adjustment for potential confounders, we found a marginally significant decrease in gastric cancer risk in relation to total vegetable intake but not total fruit intake: the multivariate-adjusted HR (95% CI; P for trend) for the highest versus the lowest quintile of total vegetable intake was 0.89 (0.77-1.03; P for trend = 0.13) among men and 0.83 (0.67-1.03; P for trend = 0.40) among women. For distal gastric cancer, the multivariate HR for the highest quintile of total vegetable intake was 0.78 (0.63-0.97; P for trend = 0.02) among men. CONCLUSIONS: This pooled analysis of data from large prospective studies in Japan suggests that vegetable intake reduces gastric cancer risk, especially the risk of distal gastric cancer among men.

Body mass index and breast cancer risk in Japan: a pooled analysis of eight population-based cohort studies.

BACKGROUND: A positive association between body mass index (BMI) and breast cancer risk among postmenopausal women has been reported, and a weak inverse association has been suggested among premenopausal women from studies in the Western population. The effects of BMI on breast cancer have remained unclear among the Asian population, especially in premenopausal women. METHODS: We assessed the associations between BMI and breast cancer incidence by a pooled analysis from eight representative large-scale cohort studies in Japan. Cancer incidence was mainly confirmed through regional population-based cancer registries and/or through active patient notification from major local hospitals. Breast cancer was defined as code C50 according to ICD10. Pooled estimates of the hazard ratios (HRs) and 95% confidence interval (CIs) for breast cancer were calculated using random-effects models. RESULTS: Analytic subjects were 183 940 women, 1783 of whom had breast cancer during 2 194 211 person-years of follow-up. A positive association between BMI and the risk of postmenopausal breast cancer was observed (trend P<0.001). The HRs for premenopausal breast cancer were 1.05 (95% CI 0.56-1.99), 1.07 (95% CI 0.76-1.52), 0.91 (95% CI 0.64-1.30), 1.15 (95% CI 0.76-1.73), 1.45 (95% CI 0.71-2.94), and 2.25 (95% CI 1.10-4.60), respectively, in BMIs of <19, 19 to <21, 21 to <23, 25 to <27, 27 to <30, and ≥30 kg/m2. These results were not substantially altered after excluding the patients who were diagnosed with breast cancer in the first 2 years of follow-up. CONCLUSIONS: The increased risk of postmenopausal breast cancer among women with higher BMIs was confirmed in Japanese. A borderline-significant positive association between BMI and premenopausal breast cancer was observed, suggesting that body mass in Asian women might have opposite effects on breast cancer compared with Western women.

Serum pyridoxal concentrations and depressive symptoms among Japanese adults: results from a prospective study.

BACKGROUND/OBJECTIVES: Vitamin B6 is suggested to have a protective role against depression. However, the association between vitamin B6 intake and depression remains inconclusive, and few studies have examined the relationship between circulating vitamin B6 concentrations and depressive symptoms. Here, we investigated the cross-sectional and prospective associations between serum pyridoxal concentrations and depressive symptoms among Japanese workers. SUBJECTS/METHODS: Participants were 422 municipal employees (aged 21-67 years) who participated in a baseline survey in 2006 for cross-sectional analysis, and 210 subjects without depressive symptoms at baseline (2006) who completed both baseline and follow-up (2009) surveys for prospective analysis. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) scale. Logistic regression analysis was used to estimate the odds ratio of depressive symptoms (CES-D scale of ≥ 19) according to tertile of serum pyridoxal with adjustment for potential confounding variables. RESULTS: In the cross-sectional analysis, serum pyridoxal concentrations were significantly associated with a decreased prevalence of depressive symptoms (P for trend=0.03); the multivariable-adjusted odds ratio of depressive symptoms for the highest tertile of pyridoxal was 0.54 (95% confidence interval 0.30-0.96) compared with the lowest tertile. In longitudinal analyses, higher serum pyridoxal concentrations at baseline were associated with a trend toward reduced depressive symptoms after 3 years; the multivariable-adjusted odds ratio of depressive symptoms for the highest versus the lowest tertile of pyridoxal concentration was 0.55 (95% confidence interval 0.13-2.32). CONCLUSIONS: A higher vitamin B6 status may be associated with a decreased risk of depressive symptoms in Japanese.

Short sleep duration in association with CT-scanned abdominal fat areas: the Hitachi Health Study.

OBJECTIVE: To examine the relationship between short sleep duration and body mass index (BMI), waist circumference (WC), visceral fat area (VFA) and subcutaneous fat area (SFA) among a working population in Japan. DESIGN: Health-center-based, cross-sectional study. SUBJECTS: The study subjects included 5400 men and 642 women aged 30 to 75 years who underwent an abdominal computed tomography (CT) scanning examination in a comprehensive health checkup. MEASUREMENTS: Height and weight were measured, and BMI was calculated. WC, VFA and SFA were measured using a CT scanner. Sleep duration was self-reported. Analysis of covariance was used to estimate adjusted means of BMI, WC, VFA and SFA across categories of sleep duration with adjustments for potential confounders. Trend of the association was assessed using multiple linear regression analysis. RESULTS: In men, the mean values of BMI, WC and SFA decreased with increasing sleep duration after adjustment for age, physical activity, smoking and drinking (P-value for trend <0.001). Additional adjustment for physical illnesses did not attenuate the explanatory power of the models (P-value for trend <0.001). In addition, the association between sleep duration and SFA did not change after controlling for VFA (P-value for trend <0.001). The mean values of SFA for subjects sleeping '<5 h', '5 to <6 h', '6 to <7 h' and '7 h' per day were 145.8±67.4 cm(2), 138.7±61.5 cm(2), 134.7±60.4 cm(2) and 132.5±49.2 cm(2), respectively. Sleep duration was not appreciably associated with VFA. In women, no significant association was detected in any models. CONCLUSION: Shorter sleep duration is associated with higher BMI, WC and SFA in men. Further research is needed to explicate the biological mechanisms behind these relationships and to see whether interventions addressing inadequate sleep could treat or prevent obesity by taking gender differences into consideration.

Dietary patterns and type 2 diabetes in Japanese men and women: the Japan Public Health Center-based Prospective Study.

BACKGROUND/OBJECTIVE: Dietary patterns in Western populations have been linked to type 2 diabetes, but the association of distinctive dietary patterns of Japanese population remains unclear. We prospectively investigated the association between dietary patterns and risk of developing type 2 diabetes among Japanese adults. SUBJECTS/METHODS: Participants were 27, 816 men and 36,889 women aged 45-74 years who participated in the second survey of the Japan Public Health Center-based prospective study and had no history of diabetes. Dietary patterns were derived by using principal component analysis of the consumption of 134 food and beverage items ascertained by a food frequency questionnaire. Odds ratios of self-reported physician-diagnosed type 2 diabetes over 5 year were estimated using logistic regression analysis. RESULTS: A total of 1194 new cases (692 men and 502 women) of type 2 diabetes were self-reported. We identified three dietary patterns: prudent, westernized and traditional Japanese patterns. Any dietary pattern was not significantly associated with type 2 diabetes risk after adjustment for covariates in both men and women. The multivariate-adjusted odds ratios (95% confidence interval) for type 2 diabetes for the highest versus lowest quartile of each dietary pattern score in men and women, respectively, were 0.93 (0.74-1.16) and 0.90 (0.69-1.16) for the prudent pattern, 1.15 (0.90-1.46) and 0.81 (0.61-1.08) for the westernized pattern, and 0.97 (0.74-1.27) and 0.87 (0.66-1.15) for the traditional pattern. CONCLUSIONS: Although a small protective effect of the prudent dietary pattern cannot be excluded, dietary patterns may not be appreciably associated with type 2 diabetes risk in Japanese.

Serum 25-hydroxyvitamin D and markers of insulin resistance in a Japanese working population.

BACKGROUND/OBJECTIVES: The association between vitamin D status and insulin resistance (IR) has been less studied among Asians, and it remains elusive whether calcium could modify such an association. We examined the association of serum 25-hydroxyvitamin D (25(OH)D) concentrations with IR markers and the potential effect modification by calcium intake among a Japanese population. SUBJECTS/METHODS: The authors analyzed data (n=494) from a cross-sectional survey conducted in 2009 among a Japanese working population aged 20-68 years. Fasting serum 25(OH)D and insulin, as well as fasting plasma glucose were determined, and homeostatic model assessment of IR (HOMA-IR) was calculated. Calcium intake was assessed using a validated diet history questionnaire. Multiple linear regression was done with adjustment of potential confounding variables. RESULTS: Fasting insulin and HOMA-IR were significantly inversely associated with 25(OH)D concentration across quartiles of 25(OH)D after fully adjusting for covariates (P(trend)=0.04 and 0.02, respectively). Across clinically relevant categories of 25(OH)D, compared with participants in the vitamin D sufficiency group, those in the vitamin D insufficiency group had a 5% higher HOMA-IR score, and those in the hypovitaminosis D group had an 18% higher HOMA-IR score (P(trend)=0.01). In an analysis by calcium intake, the HOMA-IR score was highest among participants with both a low calcium intake and lowest 25(OH)D concentrations, with significant inverse trend being observed in the group with lower calcium intake (P(trend)=0.02). CONCLUSIONS: Our findings suggest that low vitamin D status is associated with IR among Japanese adults.

Association between body mass index and the colorectal cancer risk in Japan: pooled analysis of population-based cohort studies in Japan.

BACKGROUND: Obesity has been recognized as important risk factors for colorectal cancer. However, limited evidence is available on colorectal cancer and body mass index (BMI) in Asian population. METHODS: We conducted a pooled analysis of eight population-based prospective cohorts studies in Japan with more than 300,000 subjects to evaluate an impact of obesity in terms of BMI on colorectal cancer risk with unified categories. We estimated summary hazard ratio (HR) by pooling of study-specific HR for BMI categories with random effect model. RESULTS: We found a significant positive association between BMI and colorectal cancer risk in male and female. Adjusted HRs for 1 kg/m(2) increase were 1.03 [95% confidence interval (CI) 1.02-1.04] for males and 1.02 (95% CI 1.00-1.03) for females. The association was stronger in colon, especially in proximal colon, relative to rectum. Males showed a stronger association than females. Population attributable fraction for colorectal cancer by BMI ≥ 25 kg/m(2) was 3.62% (95% CI 1.91-5.30) for males and 2.62% (95% CI 0.74-4.47) for females. CONCLUSIONS: We found significant association between BMI and colorectal cancer risk by pooling of data from cohort studies with considerable number of subjects among Japanese population. This information is important in cancer control planning, especially in Asian population.

Visceral fat area cutoff for the detection of multiple risk factors of metabolic syndrome in Japanese: the Hitachi Health Study.

The relationships between metabolic risk factors and abdominal fat distribution determined using computed tomography (CT) are poorly defined in large populations. We investigated the cutoff values of the visceral fat area (VFA) to detect subjects with multiple risk factors of metabolic syndrome (MS) by sex and age groups, and attempted to examine whether sex- and age-specific cutoff values are needed. The subjects of this study were 11,561 Japanese men and women who participated in the Hitachi Health Study, received CT examination, and answered questionnaires on lifestyles between 2004 and 2009. VFA and waist circumference were measured using CT. The VFA cutoff values yielding an 80% sensitivity for the detection of multiple risk factors of MS were typically smaller among men under the age of 40 years (<40 years vs. ≥40 years; 86.4 cm(2) vs. 103.9 cm(2)). The area under the receiver operator characteristic curve of VFA for the detection tended to decrease according to age (P = 0.056 and P = 0.020 for trends in men and women). Age- and sex-specific cutoff values are needed. The sensitivity of the subjects under the age of 40 years is relatively smaller (70.0% for men and 60.0% for women) compare to other age groups when the same cutoff value is used regardless of age (e.g., cutoff value calculated to correspond to 80% sensitivity for subjects of all ages). Therefore, a smaller VFA cutoff point should be used among men under the age of 40 years.

Magnesium intake and type II diabetes in Japanese men and women: the Japan Public Health Center-based Prospective Study.

This study examined the association between magnesium intake and type II diabetes risk among Japanese adults. Participants were 25 872 men and 33 919 women aged 45-75 years who had no history of diabetes. Magnesium intake was ascertained using a 147-item food frequency questionnaire. Odds ratio of self-reported physician-diagnosed type II diabetes over 5 years was estimated using logistic regression analysis. A total of 1114 new cases of type II diabetes were self-reported. Magnesium intake was not significantly associated with type II diabetes in either men or women. The multivariable-adjusted odds ratios (95% confidence intervals) of type II diabetes for the highest versus lowest quintile of magnesium intake were 0.86 (0.63-1.16) and 0.92 (0.66-1.28) for men and women, respectively. Although a small effect cannot be excluded in men, magnesium intake may not be appreciably associated with risk of type II diabetes for Japanese adults.

Dietary patterns and depressive symptoms among Japanese men and women.

OBJECTIVE: Although several studies have reported associations of depressive state with specific nutrients and foods, few studies examined the association with dietary patterns in adults. We investigated the association between major dietary patterns and depressive symptoms in Japanese. METHODS: Subjects were 521 municipal employees (309 men and 212 women), aged 21-67 years, who participated in a health survey at the time of periodic checkup. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) Scale. Dietary patterns were derived by using principal component analysis of the consumption of 52 food and beverage items, which was assessed by a validated brief diet history questionnaire. Logistic regression analysis was used to estimate odds ratios of depressive symptoms (CES-D >or=16) with adjustment for potential confounding variables. RESULTS: We identified three dietary patterns. A healthy Japanese dietary pattern characterized by high intakes of vegetables, fruit, mushrooms and soy products was associated with fewer depressive symptoms. The multivariate-adjusted odds ratios (95% confidence intervals) of having depressive symptoms for the lowest through highest tertiles of the healthy Japanese dietary pattern score were 1.00 (reference), 0.99 (0.62-1.59) and 0.44 (0.25-0.78), respectively (P for trend=0.006). Other dietary patterns were not appreciably associated with depressive symptoms. CONCLUSIONS: Our findings suggest that a healthy Japanese dietary pattern may be related to decreased prevalence of depressive status.

Serum folate and homocysteine and depressive symptoms among Japanese men and women.

BACKGROUND/OBJECTIVES: Folate and homocysteine have been implicated to have a role in depression. However, results of epidemiologic studies on this issue have been inconsistent. The objective of this study was to clarify the association between serum folate and homocysteine concentrations and depressive symptoms in Japanese adults. SUBJECTS/METHODS: We analyzed cross-sectional data for 530 municipal employees (313 men and 217 women), aged 21-67 years, who participated in a health survey at the time of periodic checkup. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) scale. Logistic regression analysis was used to estimate odds ratios of depressive symptoms (CES-D scale scores of >or=16) with adjustment for potential confounding variables. RESULTS: In total, 113 men (36.1%) and 79 women (36.4%) had depressive symptoms. A higher serum folate was associated with a decreased prevalence of depressive symptoms in men. The multivariate-adjusted odds ratios (95% confidence interval) of depressive symptoms for the lowest to highest quartiles of serum folate were 1.00 (reference), 0.53 (0.27-1.03), 0.33 (0.16-0.68) and 0.51 (0.25-1.03), respectively (trend P=0.03). Furthermore, the data suggested a positive association between serum homocysteine and depressive symptoms in men (trend P=0.06). In women, neither folate nor homocysteine was associated with depressive symptoms. CONCLUSIONS: Low serum folate may be related to an increased prevalence of depressive symptoms in Japanese men.

Weight change and all-cause, cancer and cardiovascular disease mortality in Japanese men and women: the Japan Public Health Center-Based Prospective Study.

BACKGROUND: It is unclear whether weight change during adulthood influences subsequent mortality in Asian populations, who have a relatively lean body mass. OBJECTIVE: To assess the relation of weight change over 5 years to all-cause, cancer and cardiovascular disease mortality among Japanese men and women. DESIGN: Subjects were 36 220 men and 44 091 women aged between 45 and 75 years without a history of serious disease at baseline. Weight change was calculated as the difference of body weight between two surveys with a 5-year interval. RESULTS: During 699 963 person-years of follow-up, we identified 4232 deaths of all-cause, 1872 cancer deaths and 1021 cardiovascular deaths. The relation between weight change and all-cause mortality was reverse J-shaped. Multivariate hazard ratios (95% confidence interval) for weight loss of 5 kg or more versus weight change of less than 2.5 kg were 1.62 (1.45-1.81) in men and 1.76 (1.51-2.05) in women, whereas those for weight gain of 5 kg or more were 1.40 (1.22-1.59) in men and 1.25 (1.02-1.54) in women. These associations remained statistically significant even after the exclusion of deaths in the first 3 years of follow-up. The weight change-mortality association was pronounced in underweight persons or in nonsmoking men. The risk of cancer mortality increased in both men and women who lost weight by 5 kg or more. With regard to cardiovascular disease, mortality risk tended to increase with weight loss both in men and women, whereas its increase with weight gain was observed only in women. CONCLUSIONS: A large weight change, both loss and gain, was associated with an increased risk of mortality. Weight loss and gain may be predictors of early death in apparently healthy adult Japanese.