Skipping breakfast and 5-year changes in body mass index and waist circumference in Japanese men and women.

OBJECTIVE: This study investigated the relationship between frequency of skipping breakfast and annual changes in body mass index (BMI) and waist circumference (WC). METHODS: The participants were 4,430 factory employees. BMI and WC were measured repeatedly at annual medical examinations over a 5-year period. The association between frequency of skipping breakfast at the baseline examination and annual changes in anthropometric indices was evaluated using the generalized estimating equation method. RESULTS: The mean (standard deviation) BMI was 23.3 (3.0) kg m-2 for men and 21.9 (3.6) kg m-2 for women; and the mean WC was 82.6 (8.7) cm for men and 77.8 (9.8) cm for women. During the follow-up period, mean BMI increased by 0.2 kg m-2 for men and women, and mean WC increased by 1.1 cm for men and 1.0 cm for women. The annual change in the BMI of men who skipped breakfast four to six times per week was 0.061 kg m-2 higher, and that of those who skipped breakfast seven times per week was 0.046 kg m-2 higher, compared with those who did not skip breakfast. Annual changes in the WC of male participants who skipped breakfast seven times per week was 0.248 cm higher than that of those who did not skip breakfast. Skipping breakfast was not associated with changes in BMI or WC in women. CONCLUSIONS: Skipping breakfast was closely associated with annual changes in BMI and WC among men, and eating breakfast more than four times per week may prevent the excessive body weight gain associated with skipping breakfast.

Sugar-sweetened beverage and diet soda consumption and the 7-year risk for type 2 diabetes mellitus in middle-aged Japanese men.

PURPOSE: This cohort study investigated the association between sugar-sweetened beverage (SSB) and diet soda consumption and the incidence of type 2 diabetes in Japanese men. METHODS: The participants were 2,037 employees of a factory in Japan. We measured consumption of SSB and diet soda using a self-administered diet history questionnaire. The incidence of diabetes was determined in annual medical examinations over a 7-year period. Hazard ratios (HRs) with 95 % confidence intervals (CIs) for diabetes were estimated after adjusting for age, body mass index, family history, and dietary and other lifestyle factors. RESULTS: During the study, 170 participants developed diabetes. The crude incidence rates (/1,000 person-years) across participants who were rare/never SSB consumers, <1 serving/week, ≥ 1 serving/week and <1 serving/day, and ≥ 1 serving/day were 15.5, 12.7, 14.9, and 17.4, respectively. The multivariate-adjusted HR compared to rare/never SSB consumers was 1.35 (95 % CI 0.80-2.27) for participants who consumed ≥ 1 serving/day SSB. Diet soda consumption was significantly associated with the incident risk of diabetes (P for trend = 0.013), and multivariate-adjusted HRs compared to rare/never diet soda consumers were 1.05 (0.62-1.78) and 1.70 (1.13-2.55), respectively, for participants who consumed <1 serving/week and ≥ 1 serving/week. CONCLUSIONS: Consumption of diet soda was significantly associated with an increased risk for diabetes in Japanese men. Diet soda is not always effective at preventing type 2 diabetes even though it is a zero-calorie drink.

Effect of high-sensitivity C-reactive protein on the development of diabetes as demonstrated by pooled logistic-regression analysis of annual health-screening information from male Japanese workers.

AIM: The aim of this study was to determine the relationship between the development of diabetes mellitus and high-sensitivity C-reactive protein (HsCRP) adjusted for various potential confounders. METHODS: This 5-year prospective cohort study was conducted at a Japanese steel factory and involved male workers who had received annual health screenings between 2005 and 2010. The 7392 male participants were aged 19-75 years. The study endpoint, the development of diabetes mellitus, was defined as HbA(1c) greater or equal to 6.5% or the use of antidiabetic medication. The association between variables was investigated using pooled logistic regression adjusted for various covariates such as age, baseline body mass index (BMI) and increase in BMI from baseline, blood biochemistry, job schedule and job-related stress. RESULTS: The incidence rate of diabetes development per 1000 person-years was 13.9. Multivariate analysis showed a significant relationship between the development of diabetes and elevated levels of baseline HsCRP and increases in levels from baseline. The Odds ratios for a 2.9-fold (±1 geometric standard deviation) increase in baseline HsCRP and increase in HsCRP level from baseline were 1.18 [95% confidence interval (CI): 1.03-1.34; P=0.018] and 1.21 (95% CI: 1.03-1.41; P=0.018), respectively. CONCLUSION: The present study has indicated that HsCRP is an independent predictor for the development of diabetes in men, together with various confounders such as BMI, type of job schedule and job-related stress.

Serum gamma-glutamyltransferase and the risk of hyperuricemia: a 6-year prospective study in Japanese men.

We conducted a longitudinal study to investigate whether increased serum gamma-glutamyltransferase independently predicts subsequent development of hyperuricemia. The study participants included 3,310 Japanese men without hyperuricemia, aged 20-54 years. The participants had annual heath examinations for 6 years to assess incident hyperuricemia (defined as serum uric acid>416.4 µmol/l and/or taking medication for hyperuricemia). The risk of incident hyperuricemia was compared in participants grouped according to their baseline serum gamma-glutamyltransferase level. During follow-up, there were 529 incident cases of hyperuricemia. A positive, dose-response relationship was observed between serum gamma-glutamyltransferase and the risk of incident hyperuricemia. The hazard ratios (95% confidence intervals) for hyperuricemia, compared with a serum gamma-glutamyltransferase level ≤19 U/l, were 1.32 (1.05-1.67) for 20-39 U/l, 1.28 (0.90-1.83) for 40-59 U/l, 1.56 (0.98-2.47) for 60-79 U/l, and 1.57 (1.02-2.41) for ≥80 U/l after adjustment for baseline serum uric acid, creatinine, total cholesterol, and glycated hemoglobin levels, ln(serum alanine aminotransferase), age, systolic blood pressure, medications for hypertension, hypercholesterolemia, and diabetes, body mass index, and smoking and exercise habits. A similar positive relationship was observed regardless of the presence or absence of alcohol drinking, obesity, metabolic disorders (any combination of hypertension, hypercholesterolemia and/or diabetes), or clinically high serum aminotransferases, without evidence of a significant interaction between increased serum gamma-glutamyltransferase and risk factors for incident hyperuricemia. These findings indicate that increased serum gamma-glutamyltransferase is an independent predictor of subsequent development of hyperuricemia.

Alcohol intake and the risk of hyperuricaemia: a 6-year prospective study in Japanese men.

BACKGROUND AND AIMS: Since there is little information derived from prospective studies on the amount of alcohol drinking required to induce hyperuricaemia, we attempted to address this issue in a Japanese population. METHODS AND RESULTS: A total of 3310 Japanese men aged 20-54 years that were free of hyperuricaemia were classified according to their alcohol intake per week at baseline. Incident hyperuricaemia, defined as >7.0 mg/dl and/or taking medication for hyperuricaemia, was assessed through annual heath examinations for 6 years after the baseline examination. During follow-up, 529 incident cases of hyperuricaemia occurred. There was a positive, dose-response relationship between alcohol intake and the risk of incident hyperuricaemia. The hazard ratio (95% confidence interval) for hyperuricaemia in drinkers compared with non-drinkers was 1.10 (0.85-1.42) for <10.0 drinks/week, 1.40 (1.07-1.84) for 10.0-19.9 drinks/week, 1.64 (1.23-2.21) for 20.0-29.9 drinks/week and 1.98 (1.40-2.80) for ≥30.0 drinks/week (one drink contained 11.5 g of ethanol) after adjusting for age, baseline serum uric acid, body mass index, smoking habits, exercise habits, serum creatinine, blood pressure, serum cholesterol and blood glucose. The fraction of hyperuricaemia in the population attributable to alcohol intake was 21.6%. A clear dose-response pattern was observed for both beer and sake, when the consumption of these two beverages was analysed separately. CONCLUSION: Habitual alcohol intake significantly contributed to the development of hyperuricaemia in Japanese men, regardless of type of alcoholic beverage consumed. Therefore, it is essential to reduce excessive alcohol intake to prevent and manage hyperuricaemia.

Shift work is a risk factor for increased total cholesterol level: a 14-year prospective cohort study in 6886 male workers.

OBJECTIVES: The widespread adoption of 24 h continuous operations in a number of industries has resulted in an increase in shift work, which may influence lipid metabolism because of disturbed circadian rhythms, broken sleep and lifestyle problems. The objective of the present study was to assess the effect of shift work on serum total cholesterol as an index of lipid metabolism. METHODS: A 14-year prospective cohort study was conducted in day workers (n = 4079) and alternating shift workers (n = 2807) who received annual health check-ups between 1991 and 2005 in a Japanese steel company. The end-points were either a 20%, 25%, 30%, 35%, 40% or 45% increase in serum total cholesterol during the period of observation, compared with serum total cholesterol at entry to the study. The association between the job schedule type and increase in serum total cholesterol was investigated using multivariate pooled logistic regression analyses. The odds ratios for the effect of shift work were obtained after adjustment for a number of potential confounders. RESULTS: The significant odds ratios of alternating shift work (and 95% confidence intervals) were: >or=20%, 1.16 (1.07 to 1.26); >or=25%, 1.16 (1.05 to 1.28); >or=35%, 1.23 (1.05 to 1.43); >or=40%, 1.30 (1.07 to 1.58); and >or=45%, 1.28 (1.01 to 1.63) for serum total cholesterol. CONCLUSION: Generally the odds ratios of alternating shift work tended to be higher for stricter cut-points of relative increase in serum total cholesterol level. Our study in male Japanese workers revealed that alternating shift work adversely affected lipid metabolism.

Combination of the C1429T polymorphism in the G-protein beta-3 subunit gene and the A1330V polymorphism in the low-density lipoprotein receptor-related protein 5 gene is a risk factor for hypercholesterolaemia.

The present study examined the relationship between genetic combinations of the C1429T polymorphism in the G-protein beta-3 subunit (GNB3) gene and the A1330V polymorphism in the low-density lipoprotein receptor-related protein 5 (LRP5) gene and the risk of hypercholesterolaemia in Japanese workers. The present study included observations from 1997 to 2002 in 927 males and 662 females who were not hypercholesterolaemic on entry. The endpoint was the development of hypercholesterolaemia, defined as a total cholesterol level > or =240 mg/dl. The odds ratios for the combination of polymorphisms were calculated using pooled logistic regression analyses that incorporated other potential factors into the model. The odds ratios in males and females with GNB3/1429TT and LRP5/1330VV or AV genotypes were 4.17 compared to males with the 1429CT or TT and 1330AA genotypes and 3.53 compared to females with the 1429CC, CT or TT and 1330AA genotypes. Assuming these effects were a mere addition of two independent effects, the odds ratios for both GNB3/1429TT and LRP5/1330VV or AV were estimated to be 3.27 for males and 1.42 for females. Therefore, the synergic effects were shown to be 1.28 times in males (not significant) and 2.49 times in females (P<0.05 by bootstrap method). These results provide clear evidence that the genetic combination has a synergic effect. This study indicates that the combination of GNB3/C1429T and LRP5/A1330V is a very useful marker for predicting the development of hypercholesterolaemia in the general Japanese population.

G-protein beta3 subunit variant C825T is a risk factor for hypertension in Japanese females--a prospective cohort study over 5 years.

The relationship between the G-protein beta3 subunit variant C825T and risk of hypertension was examined in a prospective cohort study of Japanese workers. This study included observations over a 5-year period from 1997 to 2002 on 878 males and 692 females who were normotensive at entry. Hypertension was defined as systolic blood pressure > or =140 mmHg and/or diastolic blood pressure > or =90 mmHg, or taking antihypertensive medication. Pooled logistic regression analyses were performed using C825T genotype, age, body mass index, lifestyle, and the result of blood chemistries as the covariates. Multivariate pooled logistic regression analysis showed the risk of hypertension was 2.31 times higher in females with the TT genotype than in females with the CC genotype (95% confidence interval: 1.07-4.96), after adjustment for the effects of other potential covariates. In contrast, no significant risk of hypertension was observed with the TT genotype in male subjects. This study indicates that the 825T allele is an independent risk factor for hypertension in Japanese females, and suggests that this polymorphism may be a beneficial prognostic marker for hypertension in the general Japanese female population.

Creatinine versus specific gravity-adjusted urinary cadmium concentrations.

The aim was to assess how urinary creatinine is affected by age, gender, body size and meat intake, and to determine to what extent such factors might affect the creatinine adjustment of urinary cadmium. The study was based on three Swedish studies: (1) 67 non-smoking women aged 20-50 years (24-h urine samples); (2) 289 men and 434 women aged 16-81 years (spot urine samples); and (3) 98 men and 105 women aged 19-72 years (spot urine samples). The effects of age, body surface area (as an indicator of muscle mass), and meat intake on urinary creatinine and cadmium were analysed using multiple regression analyses. Gender- and age-related variations in urinary creatinine and cadmium adjusted for creatinine or specific gravity were compared by ANOVA or ANCOVA. In the multiple regression analyses, body surface area, gender, age and meat intake were the major determinants of urinary creatinine. Urinary cadmium adjusted for creatinine and specific gravity were also dependent on body size, gender and age. Urinary cadmium adjusted for creatinine was 15-92% higher in women or older individuals than in men or younger individuals. Women or older individuals had -3 to 79% higher urinary cadmium adjusted for specific gravity than men or younger individuals had, and such a difference between gender or age group was less obvious in specific gravity adjustment than in creatinine adjustment. Thus, urinary cadmium adjusted for creatinine is more affected by age, gender, body size and meat intake than is specific gravity adjustment. When comparing individuals or populations with large differences in muscle mass or meat intake, such effects can be especially important. In such studies, specific gravity adjustment seems to be more appropriate.

A follow-up study on the association of working conditions and lifestyles with the development of (perceived) mental symptoms in workers of a telecommunication enterprise.

AIM: This study investigated the association of working conditions and lifestyle with mental health in Japanese workers. METHODS: A follow-up study was carried out in the Kanto district of Japan of workers in a telecommunications enterprise who received their first annual health check-up between 1992 and 1996 and were between 20 and 54 years old. Workers who reported mental symptoms, had a past history of disease, or current illness at their first check-up were excluded from the analysis. In total, the study included 23 837 workers. The association between working conditions and lifestyle and the development of mental symptoms was investigated by pooled logistic regression analyses. RESULTS: Working long hours and part-time work, as opposed to normal daytime hours of work, were factors associated with the development of mental symptoms in males, as were smoking, short sleeping hours, little physical exercise, rarely taking three meals a day, frequently eating within 1 h before sleep, much preference for salty meals and little preference for vegetables. Consumption of alcohol was negatively associated with the development of mental symptoms in males. Overall, the results suggested that the lower the Healthy Work and Lifestyle Score, the higher the risk of developing mental symptoms. CONCLUSIONS: Working conditions and lifestyle, especially food preferences, have an apparent influence on the mental health of Japanese workers. Moreover, the Healthy Work and Lifestyle Score indicates that working conditions and lifestyle appear to have a cumulative influence upon the mental health of Japanese workers.

Influence of years engaged in agriculture and number of pregnancies and deliveries on mortality of inhabitants of the Jinzu River basin area, Japan.

BACKGROUND: The occurrence of itai-itai disease is thought to be affected by such factors as pregnancy, lactation, hormonal disorders, aging, and calcium deficiency. AIMS: To study the influence of years engaged in agriculture and number of pregnancies and deliveries on the mortality of inhabitants of the Jinzu River basin area, which has been an endemic region for itai-itai disease. METHODS: From 6,667 participants (3,181 men, 3,486 women; participation rate 93.4%) in the 1967 health survey, 3,639 subjects (1,591 men, 2,048 women) whose years engaged in agriculture were established, and 2,559 women/2,410 women with a known number of pregnancies/deliveries were selected as the target population. These data were confirmed on the basis of self reported replies confirmed afterwards by interview. The survival survey was conducted for 6,127 days from 1 August 1967 to 10 May 1984. Subjects were divided according to three water systems: the Jinzu River, non-Jinzu River, and mixed water system; the influence on mortality of the years engaged in agriculture and the number of pregnancies/deliveries was analysed using a Cox's proportional hazards model according to the water systems. RESULTS: The mean years engaged in agriculture and mean number of pregnancies/deliveries were not different among the three water systems. Cox's hazard ratios of these parameters to mortality were not statistically significant in the any of the water systems. CONCLUSIONS: Neither the years engaged in agriculture nor the number of pregnancies/deliveries influenced mortality in subjects living not only in the non-Jinzu River basin but also in the Jinzu River basin using a Cox's proportional hazards model.

An association between smoking habits and blood pressure in normotensive Japanese men.

We conducted a cross-sectional study to clarify the dose-effect relationship of smoking habits with blood pressure in Japanese men. The subjects were 2781 normotensive male steelworkers ranging in age from 40 to 54 years. They were classified into five categories according to their smoking habits: non-smokers, ex-smokers, light smokers, moderate smokers and heavy smokers. Age, body mass index, salt intake, physical activity, drinking habits, and levels of gamma-glutamyl transpeptidase, total serum cholesterol, uric acid, creatinine and plasma glucose were analysed as covariates. The association between smoking habits and blood pressure was evaluated using analysis of covariance. Our results showed that there was no significant difference in the adjusted systolic and diastolic blood pressure between non-smokers and ex-smokers. The adjusted systolic and diastolic blood pressures in light, moderate and heavy smokers were significantly lower than in non- and ex-smokers. However, among smokers, no significant difference was observed in correlation with smoking amount. In conclusion, blood pressure of smokers was lower than that of non- and ex-smokers. However, there were no significant dose-effect relationships between smoking amount and blood pressure when lifestyle and other confounding factors were considered.

Alcohol consumption and blood pressure change: 5-year follow-up study of the association in normotensive workers.

This study endeavours to clarify the effect of alcohol consumption on changes in the blood pressure of Japanese men. The subjects, who were followed from 1990 to 1995, were 2189 male normotensive steelworkers aged from 40 to 54 years in 1990. Drinking habits were represented by two variables: average daily baseline alcohol consumption, and change in alcohol consumption during the observation period, both derived from self-report questionnaires and interviews. Nine other items were analysed as covariates: systolic and diastolic blood pressure, age, body mass index (BMI), salt intake, physical activity, and levels of gamma glutamyl transpeptidase (GTP), uric acid and plasma glucose in 1990. The association between drinking habits and blood pressure was evaluated using ANCOVA. Subjects who had initiated antihypertensive therapy by 1995 were excluded from this dataset. The results of analysis disclosed that both daily alcohol consumption and its change were significantly associated with changes in systolic and diastolic blood pressure during the observation period. J-shaped associations of daily alcohol consumption with adjusted changes in systolic and diastolic blood pressure were found. Positive associations were observed between changes in alcohol consumption and adjusted changes in systolic and diastolic blood pressure. In conclusion, daily alcohol consumption was associated non-linearly with changes in blood pressure and with a threshold effect at 18 ml of ethanol per day in these middle-aged Japanese workers. In addition, increasing alcohol consumption was associated with blood pressure elevation, and decreasing consumption was associated with suppression of blood pressure elevation.

Alcohol consumption and blood pressure in Japanese men.

In a study of Japanese men, a nonlinear association of alcohol consumption and blood pressure was not observed. This cross-sectional study was conducted to clarify the effect of infrequent or light alcohol consumption on blood pressure in normotensive Japanese men. The subjects were 2,179 male workers ranging in age from 40 to 54 years. Drinking habits were represented by three indices: episodic alcohol consumption, frequency of drinking, and monthly alcohol consumption. Seven items were analyzed as covariates: age, body mass index, salt intake, physical activity, and levels of gamma-glutamyl transpeptidase, uric acid, and plasma glucose. The association between drinking habits and blood pressure was evaluated by using analysis of covariance. Both episodic alcohol consumption and frequency of drinking were significantly associated with blood pressure in subjects aged 45 to 54 years. In those aged 40 to 44 years, there was a significant association between frequency of drinking and diastolic blood pressure. Significant associations of monthly alcohol consumption with blood pressure in every age group also were found. In subjects aged 45 to 54 years, linear associations between episodic alcohol consumption, frequency of drinking, monthly alcohol consumption, and adjusted blood pressure were observed. In those aged 40 to 44 years, nonlinear associations of monthly alcohol consumption and frequency of drinking with adjusted blood pressure were observed, and threshold effects of 540 ml of alcohol per month and a frequency of 1 to 12 days per month were found. In conclusion, habitual alcohol consumption increases blood pressure linearly in normotensive workers aged 45 to 54 years, although light consumption does not affect blood pressure in those aged 40 to 44 years.