objective: This study compared the effect of alternating shift work and day work on weight gain in Japanese male workers. Methods and Procedures: A longitudinal cohort study was conducted in day workers (n = 4,328) and alternating shift workers (n = 2,926) of a steel company who received annual health checkups over a 14-year period between 1991 and 2005. The association between the type of job schedule and weight gain was investigated using multivariate pooled logistic regression analyses. The endpoints in the study were either a 5, 7.5, or 10% increase in BMI during the period of observation, compared to the BMI at entry. Results: The type of job schedule was significantly associated with all three BMI endpoints (5% increase in BMI; odds ratio (OR) for comparison between alternating shift workers and regular day workers, 1.14; 95% confidence interval (CI), 1.06-1.23): (7.5% increase in BMI; OR, 1.13; 95%CI, 1.03-1.24: 10% increase in BMI; OR, 1.13; 95%CI, 1.00-1.28). BMI at study entry was also positively associated with the 5, 7.5, and 10% increases in BMI during the study. On the other hand, age and drinking habits were negatively associated with 5, 7.5, and 10% increases in BMI. Discussion: Our study revealed that alternating shift work was an independent risk factor for weight gain in male Japanese workers. Efficient health screening and regular checkups, combined with support to control unhealthy lifestyle factors, would be of considerable benefit for maintaining the health of Japanese shift workers.

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Evaluation of the Effects of Shift Work on Nutrient Intake: A Cross-sectional Study: Yuko MORIKAWA, et al. Department of Epidemiology andPublic Health, Kanazawa Medical University-The aim of this study was to investigate the effects of shift work on nutrient intakes, including macronutrient intake and micronutrient intake, in a large sample size. The study population included 2,254 male manual workers, 20-59 yr of age, employed in a factory. A selfadministered diet history questionnaire was used. The subjects were classified into 3 groups according to their work schedule: (i) fixed day workers; (ii) shift workers without midnight shifts; and (iii) shift workers with midnight shifts. The nutrient intakes of the groups were compared by age group. There was a significant difference in nutrient intakes between subjects aged 20-29 yr and those aged 30 yr and over. Among subjects aged 20-29 yr, the energy density value for saturated fat and the energy adjusted intakes of calcium, potassium, vitamin A, and vitamin B1 were the lowest among shift workers with midnight shifts. Among subjects aged 30 yr and over, the total energy intake was the highest among shift workers with midnight shifts; the difference was significant compared to fixed day workers. Shift workers with midnight shifts had the highest intake of cereals among subjects 30 yr of age and older. In conclusion, there were no significant differences in nutrient intakes between fixed day workers and shift workers without midnight shift. Shift work, particularly midnight shift work, affected nutrient intake. The impact of shift work on nutrient intakes differed by age and the type of shift work. (J Occup Health 2008; 50: 270-278)

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