Prospective cohort study evaluating the relationship between salted food intake and gastrointestinal tract cancer mortality in Japan.

PURPOSE: To investigate whether a high salted food intake increases the risk of gastrointestinal tract cancer mortality. METHODS: We conducted a prospective study of 6830 Japanese inhabitants to evaluate the association between salted food consumption and the risk of gastrointestinal tract cancer mortality. Data were obtained from a prospective cohort study in Japan. Salted food consumption, determined from a baseline questionnaire, was classified into the two categories of 'low intake' and 'high intake'. The Cox proportional hazards model was used to estimate hazard ratios (HRs) and 95% confidence intervals (CI). FINDINGS: Total of 174 gastrointestinal tract cancer deaths (47 esophagus cancer, 87 stomach cancer, 23 colon cancer and 17 rectal cancer) were observed during 94996 person-years of follow-up, with a mean follow-up period of 8.9 years. After adjustment for age, body mass index, physical activity, smoking, alcohol, history of diabetes mellitus and dietary items, including vegetables, fruit, tea, red meat and processed meat, the HR for stomach cancer in males with high salt intake was 2.05 (95% CI:1.25 - 3.38) whereas that of rectal cancer was 3.58 (95% CI: 1.08 - 11.89). In contrast, no association was seen in females. Further, no association was seen between higher salted food consumption and esophagus and colon cancer in either sex. CONCLUSIONS: A significant association was seen between higher salted food consumption and stomach and rectal cancer mortality in men, but not in women. No association was seen between higher consumption and esophagus and colon cancer mortality in either men or women.

Years of life lost due to cancer in a cohort study in Japan.

BACKGROUND: We estimated the burden of cancer using mortality and years of life lost according to life tables in a cohort study in Japan. METHODS: A cohort of 13,270 subjects established in the late 1980s in Japan was followed annually for the vital status of all subjects until 2003. For subjects who died, the underlying cause of death was ascertained from the death certificate. Crude mortality rate from cancer per 100,000 person-years was calculated, and years of life lost (YLL) as well as the average years of life lost (AYLL) were computed using the 1995 life tables in Japan. RESULTS: During the follow-up period, we recorded a total 839 cancer deaths (517 men and 322 women), representing 35.5% of deaths from all causes. Overall crude cancer mortality was 654.9 per 100 000 person-years in men and 312.6 in women. Total YLL due to cancer was 7035.3 years in men and 5627.0 years in women. Overall AYLL due to all cancers was 13.6 years less than life expectancy in men and 17.5 years in women. CONCLUSION: These results showed that cancer was the leading cause of death in this cohort; with stomach, liver and lung cancer the three most frequent cancers in both sexes. YLL and AYLL reflect the cost of dying from cancer in terms of years of life expectancy lost. The different mortality statistics used here may be useful in public health considerations of cancer burden.

Fish intake and the risk of fatal prostate cancer: findings from a cohort study in Japan.

OBJECTIVE: We investigated the relationship between the intake of fish and the risk of death from prostate cancer. DESIGN: Data were derived from a prospective cohort study in Japan. Fish consumption obtained from a baseline questionnaire was classified into the two categories of 'low intake' and 'high intake'. The Cox proportional hazards model was used to estimate hazard ratios (HR) and 95 % confidence intervals. SUBJECTS: Data for 5589 men aged 30-79 years were analysed. RESULTS: A total of twenty-one prostate cancer deaths were observed during 75 072 person-years of follow-up. Mean age at baseline study of these twenty-one subjects was 67.7 years, ranging from 47 and 79 years old. Results showed a consistent inverse association of this cancer between the high v. low intake groups. The multivariate model adjusted for potential confounding factors and some other food items showed a HR of 0.12 (95 % CI 0.05, 0.32) for the high intake group of fish consumption. CONCLUSIONS: These results support the hypothesis that a high intake of fish may decrease the risk of prostate cancer death. Given the paucity of studies examining the association between prostate cancer and fish consumption, particularly in Asian populations, these findings require confirmation in additional cohort studies.

Mortality attributable to cigarette smoking in a cohort study in Japan.

We conducted this study to estimate the association and population attributable risk (PAR) of smoking with all-cause and cause-specific mortality based on a general prospective cohort study in Japan. A total of 8,129 subjects (3,996 males and 4,133 females) aged 40 or over were analyzed. The follow-up period was from 1986 to 2003. Smoking habit was classified into three categories of never smoker, former smoker, and current smoker. The Cox proportional hazard model was used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI). We also estimated the PAR of smoking, and calculated the 95% CI of PAR based on the bootstrap procedure. A total of 112,151 person-years were counted for 8,129 subjects over an average of 13.7 years of follow-up. The results showed that smoking increased the risk of dying from all cancers, cardiovascular, and respiratory diseases in both sexes. For all causes of death, smokers had a HR of 1.30 (95% CI: 1.09, 1.54), PAR of 13.1% (95% CI: 7.6, 22.3) in males, and HR of 1.81 (95% CI: 1.43, 2.29), and PAR of 6.1% (95% CI: 3.1, 9.3) in females compared to never smokers. These results confirm an increased risk of mortality from all causes, as well as from all cancers, cardiovascular disease, and respiratory disease in relation to smoking habit. Smoking is responsible for a considerable proportion of deaths due to all causes as well as cause-specific deaths. Population-based antismoking programs should be implemented to reduce such avoidable deaths.

A prospective study of green tea consumption and oral cancer incidence in Japan.

PURPOSE: To examine the relation of green tea consumption with oral carcinogenesis, we prospectively analyzed data from a nationwide large-scale cohort study in Japan. METHODS: A total of 20,550 men and 29,671 women aged 40-79 years, without any history of oral and pharyngeal cancer at baseline survey, were included in the present study. During a mean follow-up period of 10.3 years, 37 oral cancer cases were identified. The Cox proportional hazard model was used to estimate the hazard ratio (HR) and 95% confidence interval (95% CI) for oral cancer according to green tea consumption by sex, while adjusting for age, smoking, alcohol drinking, and other dietary factors. RESULTS: For women, the HRs of oral cancer for green tea consumption of 1-2, 3-4, and 5 or more cups per day were 0.51 (95% CI: 0.10-2.68), 0.60 (95% CI: 0.17-2.10), and 0.31 (95% CI: 0.09-1.07), respectively, compared with those who drank less than one cup per day (p for trend, 0.08). For men, no such trends were observed. CONCLUSIONS: Our findings did not suggest a prominent inverse association of green tea consumption with oral cancer, although there was a tendency for a reduced risk in women.

Mortality and risk factors for stroke and its subtypes in a cohort study in Japan.

OBJECTIVE: To estimate stroke mortality and evaluate risk factors for total stroke deaths and its two principal subtypes in a cohort study in Japan. METHODS: A total of 9651 subjects aged 40 or over and free of stroke were analyzed in a cohort study conducted in Fukuoka Prefecture, Japan. The follow-up period was from 1986 to 2003. Mortality rate per 100,000 person-years of stroke was estimated. The Cox proportional hazards model was used to estimate the hazard ratios and 95% confidence interval. RESULTS: A total of 226 stroke deaths were recorded during 132,972 years of follow-up. Among these, 47 were intracerebral hemorrhage and 109 were cerebral infarction. Stroke mortality rates were 209.4 per 100,000 person-years in males, and 140.5 in females. The results showed that advanced age, male gender, low body mass index (BMI), history of diabetes, hypertension, and transfusion were associated with an increased risk of mortality from total stroke. CONCLUSION: We confirmed that advanced age, male gender, low BMI, history of diabetes, history of hypertension and history of transfusion were associated with an increased risk of total stroke mortality. In addition, the magnitude of these associations differed between the two principal stroke subtypes.

Prospective study of vegetable consumption and liver cancer in Japan.

We examined the relationship between vegetable consumption and the risk of death from liver cancer in a cohort study in Japan. This analysis is based on data from 6,049 subjects aged 40 to 79 years enrolled in a cohort study conducted in Fukuoka Prefecture, Japan. The follow-up period was from 1986 to 1999. All liver cancer deaths were recorded. The vegetable consumption was classified into 3 groups: "once per week or less," "2-4 times per week" and "daily intake." The Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence interval (95% CI). A total of 51 male and 22 female liver cancer deaths were recorded during 62,343 person-years of follow-up. The "once per week or less" group was considered the referent group. In males, the multivariate HRs of liver cancer deaths were 0.61 (95% CI: 0.33-1.14) and 0.25 (95% CI: 0.11-0.59) in the "2-4 times per week" and "daily intake" groups, respectively. In females, the multivariate HRs were 0.44 (95% CI: 0.13-1.51) and 0.51 (95% CI: 0.16-1.69), respectively. The multivariate HRs were also reported by history of hepatitis and cirrhosis. In those without a history of these conditions, the multivariate HRs were 0.54 (95% CI: 0.27-1.09) and 0.36 (95% CI: 0.16-0.83). In those with a history of these conditions, the multivariate HRs were 0.58 (95% CI: 0.22-1.56) and 0.37 (95% CI: 0.13-1.06), respectively. Our study reveals an inverse association between vegetable consumption and the risk of death from liver cancer. These results provide further evidence of the protective effect of vegetables against liver cancer.

Visual display terminal work and sick building syndrome--the role of psychosocial distress in the relationship.

The present study investigated the association between visual display terminal (VDT) work and sick building syndrome (SBS) and the role of psychosocial factors in the relationship. Subjects were 2,161 Japanese office workers who responded to a cross-sectional anonymous self-administered questionnaire survey. Questions included were derived from the Miljömedicin 040, a validated questionnaire on SBS symptoms. After exclusion of data with missing information, data for 1,881 subjects were used for analysis. Multivariate logistic regression was used to estimate the odds ratio for SBS with adjustment for potential confounding factors, including psychosocial work stress. In multivariate analysis, the odds ratio for SBS was significantly elevated for men engaged in VDT work for 4 or more hours a day (OR=2.5, 95%CI: 1.0, 5.9) compared with less than 1 hour a day, showing a significant trend association (P for trend=0.04). In women, although the odds ratio for SBS with VDT use of 4 or more hours a day was somewhat elevated with adjustment for non-psychosocial factors (OR=1.5, 95%CI: 0.5, 4.3), the increase was greatly attenuated after adjustment for psychosocial work distress (OR=1.1). In conclusion, our study suggests that extended hours of VDT use might be related to increased SBS symptoms. Moreover, psychosocial distress related to VDT work might mediate the relationship between VDT use and SBS symptoms in women.

Designing scaffolds of peptides for phage display libraries.

Phage display is a powerful method for the discovery of peptide ligands that are used for analytical tools, drug discovery, and target validations. Phage display technology can produce a huge number of peptides and generate novel peptide ligands. Recently, phage display technology has successfully managed to create peptide ligands that bind to pharmaceutically difficult targets such as the erythropoietin receptor. As a result of the structural analysis of their ligands, we found that the conformational design of peptides in library is important for selecting high-affinity ligands that bind to every target from a phage peptide library. Key issues concern constraints on the conformation of peptides on the phage and the development of chemically synthesized peptides derived from peptides on phage. This review discusses studies related to the conformation of peptides selected from phage display peptide libraries in addition to the conversion from peptides to non-peptides.

Lack of an association between serum level of transforming growth factor beta -1 and stomach cancer risk in the JACC study.

Alterations in the serum concentration of transforming growth factor beta-1 (TGFbeta1) have been observed in gastric cancer patients. No study, however, has ever examined the association between the serum TGFbeta1 level and stomach cancer prospectively. We conducted a prospective, nested case-control analysis among apparently healthy men and women who were followed for up to 8 years in the JACC Study to assess whether serum level of total TGFbeta1 is associated with a subsequent risk of stomach cancer. The concentration of serum TGFbeta1 in previously collected blood samples was analyzed by ELISA for 209 individuals in whom a diagnosis of stomach cancer was documented, and for 409 controls matched with them for gender, age and study area. Baseline blood levels of TGFbeta1 were not related to the risk of stomach cancer in either men or women, a finding unchanged even after adjustment for potential confounders. The multivariate-adjusted odds ratio of stomach cancer in men and women was 1.10 (95% CI, 0.82 to 1.48) and 1.09 (95% CI, 0.80 to 1.48), respectively, for each increase of 1 SD in the TGFbeta1 value. In conclusion, serum TGFbeta1 levels were not associated with increased risks of subsequent stomach cancer.gene A52C polymorphism related to the metabolism of long-chain fatty acids and oxidized LDL in the etiology of colorectal cancer.

Green tea and stomach cancer--a short review of prospective studies.

BACKGROUND: In Japan, green tea has been drunk for a long time. Because it can be drunk casually, many people love drinking it. If such green tea has an effect to prevent stomach cancer, it will be a very convenient way to prevent the disease. METHODS: To examine the association between green tea consumption and the risk of stomach cancer, past epidemiologic studies including JACC Study were reviewed. RESULTS: Among eight case-control studies, five showed risk reduction with a statistically significant difference, and two studies showed risk reduction without a statistically significant difference. The remaining study showed the opposite result. Among six prospective studies regarding stomach cancer, no study showed risk reduction with a statistically significant difference. Four of the six studies showed no relation. In terms of study design, prospective studies, which are considered to be more reliable than case-controlled studies, tend to show no risk reduction. The results of case-control studies and prospective studies present considerably different impressions. CONCLUSIONS: Prospective studies showed no inverse association between the consumption of green tea and the risk of stomach cancer.

Cigarette smoking and mortality due to stomach cancer: findings from the JACC Study.

BACKGROUND: Several epidemiologic studies reported the positive association between cigarette smoking and stomach cancer. The prevalence of smoking in men remains high in Japan compared to other developed countries. It is therefore of great importance to determine the impact of cigarette smoking on stomach cancer among the Japanese population. The Japan Collaborative Cohort Study (JACC Study) provided an opportunity to examine the association between smoking and the risk of mortality due to stomach cancer. METHOD: A baseline survey was conducted throughout Japan from 1988 through 1990 among 110,792 inhabitants of 45 areas. Data retrieved for 98,062 participants (43,482 male and 54,580 female) who provided sufficient information about their smoking habits, without any history of caner at the baseline. Of total 970,251 person-years, 757deaths due to stomach caner were identified. RESULTS: Current smokers were at a higher risk of death due to stomach cancer than non-smokers (Hazard ratio=1.36; 95% confidence interval [CI]: 1.07, 1.73). The risk of stomach cancer for men who smoked 15 or more cigarettes per day was approximately 1.4-fold greater than that of non-smokers, and those who smoked 35 or more cigarettes per day had an approximately 1.7-fold higher risk of stomach cancer, although the dose-response trend among men was unclear (p for trend=0.063). No associations between smoking and stomach cancer were detected among women. CONCLUSION: The present results, together with previous findings, strongly support a hypothesis that cigarette smoking increases the risk of stomach cancer in Japanese men.

Serum pepsinogen values and Helicobacter pylori status among control subjects of a nested case-control study in the JACC study.

BACKGROUND: Helicobacter pylori infection and serum pepsinogen values are strongly related with stomach cancer. The aim of this study was to know what were these factors among general population. METHODS: Subjects were randomly selected 633 control subjects in a nested case-control study for risk of stomach cancer. Most of them were from rural areas of Japan. Using frozen sera, pepsinogen I (PG I) and II (PG II) values and H. pylori antibody were measured. Those with PG I less than 50 ng/mL and the ratio of PG I to PG II (PG I/II) was less than 2.0 were defined as severe, those with PG I less than 70 ng/ml and PG I/II less than 3.0 were defined as mild and the other subjects were defined as no serological atrophy. RESULTS: About 70% of the subjects were H. pylori seropositive and the seroprevalence did not depend on age or sex. Percentages of those with severe serological atrophy increased with age from 10% in those aged 40-49 years to 38% in 70 and more, and percentages of those with mild serological atrophy were about 30% independent of age. CONCLUSIONS: The subjects, who were expected to represent populations of rural area of Japan, had high prevalence of both H. pylori infection and serological atrophy of gastric mucosa. These facts should be considered in discussing results of the nested case-control study.

Serum levels of insulin-like growth factor I, II, and binding protein 3, transforming growth factor beta-1, soluble fas ligand and superoxide dismutase activity in stomach cancer cases and their controls in the JACC Study.

BACKGROUND: The prognosis of stomach cancer with advanced stage remains poor. New biomarkers of the disease that may contribute to establish the potential screening strategy would be of value for the early detection of individuals at high risk of the disease. METHODS: We conducted a prospective, nested case-control analysis among apparently healthy men and women who were followed for up to 8 years in the Japan Collaborative Cohort (JACC) Study, to evaluate serum levels of insulin-like growth factor I, II, and binding protein 3 (IFG-I, IGF-II, and IGFBP-3), transforming growth factorbeta-1 (TGFbeta1), soluble fas (sFas) and superoxide dismutase activity (SOD) in 210 stomach cancer cases diagnosed in the JACC Study in relation to those levels in their 410 controls. RESULTS: Among 6 serum biomarkers tested for case-control differences, only sFas level in female stomach cancer cases was significantly higher than that of controls (2.22 pg/ml vs. 2.04 pg/mL, respectively; P=0.013 by two-way analysis of covariance controlling for matching variable). CONCLUSION: None of the biomarkers consistently predicted future risk of stomach cancer in both men and women in the present analysis. Serum sFas level in women, however, should be studied much more thoroughly whether it provides meaningful refinement of risk stratification, or it elucidate the mechanisms of tumorigenesis in women.

Mortality and incidence rates of stomach cancer in the JACC Study.

BACKGROUND: The objective of this study was to examine the mortality and incidence of stomach cancer in the Japan Collaborative Cohort Study (JACC Study), and compare them with those of the general population of Japan. METHODS: The cohort study involved 127,477 people living in 45 municipalities in Japan. The deaths due to stomach cancer were ascertained by death certificates. The age-adjusted mortality rate per 100,000 was calculated based on 110,792 subjects aged between 40 and 79 years at the baseline in all study areas. The incident cases were defined as the subjects in whom stomach cancer had developed, or subjects who died of stomach cancer during the observed period of survey for cancer incidence. The age-adjusted incidence rate per 100,000 was ascertained and calculated in 64,820 people aged 40-79 years at the baseline living in 24 study municipalities with cancer registries. Then, the mortality rate was compared with the mortality data published in vital statistics of Japan of 1995, and the incidence rate compared with the incidence data published in The Research Group for Populationbased Cancer Registration in Japan of 1992. RESULTS: During more than 10 years of follow-up, there were 582 male deaths and 287 female deaths due to stomach cancer. The age-adjusted mortality rate was 93.4/100,000 person-year (95% confidence interval [CI]: 84.6-102.2) in males and 31.1 (95% CI: 27.0-35.3) in females. There were 646 incident cases in males and 370 in females. The age-adjusted incidence rate was 245.3 / 100,000 person-year (95% CI: 221.6-268.9) and 94.8 (95% CI: 83.0-106.6) in males and females, respectively. CONCLUSION: The mortality rate of stomach cancer in the JACC Study was lower than that in the vital statistics in Japan. Similar incidence rate of stomach cancer seems to be found between data of the JACC Study and that of the Research Group for Population-based Cancer Registration, but care is needed to interpret this similarity, because it might be due to different degree of completeness of incidence survey between the 2 studies.

Dietary habits and stomach cancer risk in the JACC Study.

BACKGROUND: Despite a declining incidence, stomach cancer is still a dominant cancer in Japan. The association between dietary habits and stomach cancer risk was investigated in a large prospective study in Japan. METHODS: Data were obtained using a self-administered questionnaire from 1988 through 1990. Food frequency questionnaire was used to evaluate the consumption of 33 selected food items. Proportional hazard model was used to determine the hazard ratios (HRs) and their 95% confidence intervals (CIs) of stomach cancer for different levels of the dietary intakes. RESULTS: A western style breakfast showed an inverse association with stomach cancer risk in males (HR=0.49, 95% CI: 0.35-0.70). Women who consumed liver three to four times per week and more than once per day had a significant increased risk, respectively (HR=2.02, 95% CI: 1.12-3.63, HR=3.16, 95% CI: 1.16-8.62 ). A clear dose-response relationship between the intake of liver and stomach cancer risk was observed. We found no association between stomach cancer mortality and the consumption of fruit such as mandarin orange, and vegetables such as carrots and spinach in both men and women. The consumption of high salt foods such as miso soup and pickles was also not significantly associated with the mortality of stomach cancer in both sexes. CONCLUSION: This prospective study suggested that a western-style breakfast is associated with a lower risk of stomach cancer, although some differences in the association were seen between men and women.

Reproducibility and validity of a self-administered food frequency questionnaire used in the JACC study.

BACKGROUND: A self-administered questionnaire on dietary habits used in the JACC Study contained a 40-item food frequency questionnaire (FFQ). Although more than 110 thousand subjects enrolled in JACC Study and responded to the FFQ, no validation study has been conducted to date. METHODS: Eighty-five volunteers among the cohort members completed 2 FFQs (FFQs 1&2) and 12-day weighed dietary records (WDR). The interval between the two FFQs was one year. During the one year, the subjects carried out a 3-consecutive-day WDR in each season. We tested the reproducibility by using two FFQs. Also, we tested the validity of the FFQ by using the 12-day WDR as a gold standard. RESULTS: The intake frequencies of the 2 FFQs often agreed, showing the Spearman correlation coefficients ranging from 0.42 (edible wild plants) to 0.86 (coffee). The Spearman correlation coefficients of the energy and nutrient intakes from FFQ2, and that of the 12-day WDR were 0.20(energy) to 0.46 (animal protein, potassium). After adjusting the energy intake, the correlation coefficients showed 0.21(fish fat) to 0.51(animal fat). When classifying the FFQ2 and WDR by quartiles and examining the degree of agreement between the two methods, we obtained its median 30%. CONCLUSIONS: The FFQ is suitable to deal with a large group of subjects. However, since the energy and the amount of nutrient intake from this FFQ can not show the overall dietary intake situation, the subjects' dietary intake should be assessed by categories.

Prospective cohort study of stress, life satisfaction, self-rated health, insomnia, and suicide death in Japan.

The association between many psychosocial factors and risk of suicide was examined. A cohort was conducted over 14 years of follow up among the general population (15,597 people) in Japan. A baseline survey of psychosocial characteristics was conducted by self-administrated questionnaire. The relative risks of occasional emotional stress, difficulty maintaining sleep, and reporting unhealthy as their self-rated health are 3.2 (95% CI: 1.3, 7.6), 2.4 (95% CI: 1.3, 4.3) and 2.6 (95% CI: 1.1, 6.2), respectively. The importance of these observations lie in its potential for improving physician and public awareness of psychosocial factors as an early indication of mental health morbidity.

Prospective study of screening for stomach cancer in Japan.

Although screening for stomach cancer is a widespread community service in Japan, the benefits of the screening program remain unclear. Our study investigated prospectively the relation between participation in stomach-cancer screening during the past 12 months and subsequent deaths. Data was derived from the Japan Collaborative Cohort Study, in which 480 stomach-cancer deaths were identified during an 8-year follow-up period. Cox proportional hazard regression was used to estimate the relative risk of death from stomach cancer and that from other causes while adjusting for potential confounding factors. In men, screening participation was associated significantly with a reduced risk of death from stomach cancer (relative risk [RR] = 0.54; 95% confidence interval [CI] = 0.41-0.70). The extent of the risk reduction was greater than potential health selection (for deaths other than stomach, RR = 0.71). The adjustment for potential confounding variables, however, attenuated the difference in risk of death (stomach cancer, RR = 0.65; other causes, RR = 0.71). In women, the magnitude of the association between screening participation and death from stomach cancer (RR = 0.74; 95% CI = 0.52-1.07) was equal to that for deaths from non-stomach cancers (RR = 0.74). Subgroup analysis showed that women with a parental history of stomach cancer had a reduced risk of death from stomach cancer associated with screening (RR = 0.32; 95% CI = 0.12-0.87). The present results underline the potential for selection bias in observational studies, and thus it remains an open question whether screening for stomach cancer is effective.

[Health-related lifestyle and mental health among inhabitants of a city in Japan].

AIM: Few studies have linked mental health to lifestyle factors in the Japanese general population. The present investigation was conducted to examine whether mental health is associated with a health-related lifestyle and how the strength of the association, if any, differs across sex and age groups, using health survey data for inhabitants of Japan. METHODS: The data used were obtained from a questionnaire survey on lifestyle and health. In 1998, the questionnaires were mailed to 2,288 subjects selected from among the inhabitants of a city in Japan, of whom 1,642 subjects (71.8%) responded. The present study included 1,343 subjects who completed all the items that were used in the analysis. The General Health Questionnaire (GHQ) -12 was used as an indicator of mental health, with 4 points or higher (high score) indicating poor mental health. Information on eight different lifestyle parameters was also obtained. Logistic regression was used to calculate the odds ratio (OR) of having poor mental health for each lifestyle. RESULTS: Subjects in poor mental health had a lower mean score for a healthy lifestyle than those in good mental health. The difference in the mean score increased with age among men, while it decreased with age among women. The OR for having poor mental health among non-exercisers was higher in the older age group among men, while it was higher in the younger age group among women. A strong association between sleep hours and mental health was observed in the older age group among men, while it was seen in the younger age groups among women. Dietary factors in general showed a clearer association with mental health among women than among men, except for the consumption of salty foods, the association of which with mental health was more evident among men. CONCLUSIONS: Mental health was found to be significantly associated with health-related lifestyles in the Japanese population. The strength of the association for each lifestyle varied considerably across sex and age groups.