BACKGROUND: The relationship between alcohol consumption and increased risk of lung cancer is controversial. This study was set up to investigate the association between alcohol consumption and death from lung cancer in a large Japanese cohort.
METHODS: The subjects comprised 28,536 males, aged 40-79 years, living throughout Japan. During 268,464 person-years of follow-up, 377 lung cancer deaths were recorded. The hazard ratio (HR) of alcohol consumption for lung cancer mortality was calculated using the Cox proportional hazards model after adjustment for age, smoking and family history of lung cancer.
RESULTS: There was no association between increased mortality from lung cancer and alcohol consumption among current drinkers. Compared with subjects who had never drunk alcohol, the HRs (95% confidence interval [CI]) of death from lung cancer for light (consuming <25.0 g ethanol per day), moderate (25.0-49.9 g per day) and heavy (≥ 50 g per day) drinkers were 0.81 (95% CI=0.61-1.07), 0.82 (0.61-1.11) and 0.97 (0.66-1.43), respectively. Further adjustment for fruit and vegetable intake did not change the results, and there was no change in HR materially after excluding those patients who died during the first 5 years of follow-up.
CONCLUSIONS: These findings indicate that alcohol consumption was not associated with increased lung cancer mortality in this population of Japanese men.
J Epidemiol 2006; 16: 49-56.

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BACKGROUND: Benefits of breast-feeding are not only limited to nutrition and sanitation in developing countries but also extend to cost-saving health care and alleviation of anxiety related to childrearing in developed countries. This study aims to elucidate factors associated with exclusive breast-feeding in Japan and use this information to achieve child-rearing support worldwide by promoting breast-feeding.
METHODS: This cross-sectional study used data from a survey conducted by Ministry of Health, Labour and Welfare of the Japanese government, the First Longitudinal Survey of Babies in 21st Century. All subjects were infants (n = 53,575) born in Japan in 2001 between January 10 and 17 and between July 10 and 17. According to the data, the exclusive breast-feeding rate in Japan during the first 6 months of life was 21.0%. We examined the factors associated with exclusive breast-feeding using univariate and multivariate logistic regression analyses.
RESULTS: Among the factors examined, the adjusted odds ratio (OR) for exclusive breast-feeding was low for late childbearing, low birth weight infants, multiple births, smoking parents, living with grandparents, and feeling burdened by childrearing. The adjusted OR was high for factors that included sufficient childcare leave and consultation about childrearing with the spouse, a birth attendant and/or nurse, and a peer in a child-rearing circle.
CONCLUSIONS: Exclusive breast-feeding is associated not only with medical factors but also with social factors. This study clarifies the necessity of social support to reduce the child rearing burden and a political system to promote paternal participation in childrearing and to improve the childcare leave system.
J Epidemiol 2006; 16: 57-63.

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BACKGROUND: Plasma fibrinogen level has been recognized as an independent risk factor for atherosclerosis and its thrombotic complications in adults. The present study aimed to clarify the association between plasma fibrinogen levels and cardiovascular risk factors in Japanese children.
METHODS: A total of 294 schoolchildren (145 boys and 149 girls) aged 10-13 years in a town in Nagano Prefecture, Japan, were surveyed in 2000 for body mass index (BMI), plasma fibrinogen, serum C-reactive protein (CRP), serum total cholesterol, serum high-density lipoprotein (HDL) cholesterol, hemoglobin (Hb) A_1c, and ratio of serum total cholesterol to serum HDL cholesterol (TCHR).
RESULTS: The mean value and standard deviation of plasma fibrinogen level among the schoolchildren was 226.0 ± 39.7 mg/dL for boys and 245.3 ± 40.9 mg/dL for girls; significantly higher for girls. Among plasma fibrinogen tertiles, serum CRP tended to increase with plasma fibrinogen in both boys and girls. An increasing trend was also found in serum total cholesterol in boys, and in TCHR, HbA_1c and BMI in girls. Multiple linear regression analysis revealed significant associations of plasma fibrinogen with serum CRP and HbA_1c in both sexes, with TCHR in boys, and with BMI in girls.
CONCLUSIONS: Plasma fibrinogen levels were associated with cardiovascular risk factors such as serum CRP, TCHR, HbA_1c, and BMI in Japanese schoolchildren.
J Epidemiol 2006; 16: 64-70.

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BACKGROUND: Carotenoids may reduce the risk for diabetes mellitus, but little is known about the association of insulin resistance with serum carotenoids in non-diabetic subjects. This study aimed to investigate whether the homeostasis model assessment-insulin resistance (HOMA-IR) index would be lower in the presence of high serum carotenoid concentrations in non-diabetic subjects.
METHODS: A total of 812 subjects (256 males and 556 females) who had received health examinations in 2003 participated in the study. The associations of the serum-carotenoid concentrations and HOMA-IR were evaluated cross-sectionally. The multivariate-adjusted geometric means of HOMA-IR by the tertiles of the serum carotenoid concentration were calculated after adjusting for age, body mass index, systolic blood pressure, total cholesterol, triacylglycerols, current tobacco use, regular alcohol intake, exercise habits and total energy intake. Associations among high HOMA-IR (3.0+ mU×mmol/L²) across tertiles of serum carotenoid concentration were assessed by tests for logistic regression analysis.
RESULTS: In male subjects, the multivariate adjusted geometric mean of HOMA-IR was inversely associated with the serum β-cryptoxanthin concentrations. In female subjects, an inverse association of the serum carotenoid concentration and HOMA-IR was observed in lycopene, β-cryptoxanthin, and zeaxanthin. The confounding factor-adjusted odds ratios (OR) for high HOMA-IR on the highest tertiles of serum α-carotene, β-carotene, β-cryptoxanthin, and zeaxanthin were 0.18 [95% confidence interval (CI): 0.06-0.52], 0.22 (95% CI: 0.07-0.67), 0.34 (95% CI: 0.12-0.96), and 0.30 (95% CI: 0.11-0.79), respectively, in male subjects. On the other hand, in female subjects, the adjusted OR for high HOMA-IR on the highest tertiles of serum lycopene and β-cryptoxanthin were 0.39 (95% CI: 0.21-0.73) and 0.51 (95% CI: 0.28-0.95), respectively.
CONCLUSIONS: The serum antioxidant carotenoids were inversely associated with HOMA-estimated insulin resistance in non-diabetic subjects.
J Epidemiol 2006; 16: 71-78.

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BACKGROUND: The association of job strain (as defined by the job demands/control model) and worksite support with nutrient intake is not clear.
METHODS: A questionnaire survey was conducted of 25,104 workers employed in nine companies in Japan. Job strain and worksite support were assessed using the Job Content Questionnaire. Daily intake of 17 nutrients was measured using a dietary history questionnaire. Data from 15,295 men and 2,853 women were analyzed, controlling for age, education, marital status, occupation, and study site.
RESULTS: Among men, job strain was positively associated with average daily intakes of fat, vitamin E, cholesterol, poly- and mono-unsaturated fatty acids (p for trend<0.05), and worksite support was positively associated with average daily intakes of total energy, crude fiber, retinol, carotene, vitamins A, C, and E, cholesterol, and saturated fatty acid (p for trend<0.05). Among women, worksite support was positively associated with average daily intakes of total energy, protein, vitamin E, and polyunsaturated fatty acid (p for trend<0.05). However these differences were generally small.
CONCLUSIONS: The present study showed that job strain and worksite support were only weakly and inconsistently associated with nutritional intakes. It does not seem that changes in nutritional intakes explain the association between job strain or worksite support and coronary heart disease.
J Epidemiol 2006; 16: 79-89.

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