Evaluation of the effects of shift work on nutrient intake: a cross-sectional study.

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 self-administered 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.