Shiftworking, nutrition and obesity: implications for workforce health- a systematic review.

BACKGROUND: Shiftworking has long been unrecognised as an occupational health hazard up until now. METHODS: Electronic databases were searched using OVID host as the main search engine for Medline, PUBMED and CINHAL during the years 1990-December 2010. Combinations of the keywords yielded 35 full papers and ab-stracts, of which 16 articles were relevant. One paper was not in English, leaving 15 included in this review after final reconsideration. Studies were categorised into two main titles: studies assessing the association between shift working and obesity and/or BMI (n=8) and studies assessing the association between shift working and nu-tritional/dietary patterns (n=7). Type of study was also considered as a part of the search strategy. RESULTS: In total, one interventional, nine cross-sectional and five cohort studies were retrieved. Seven cross-sectional studies and one cohort study showed a higher BMI/obesity prevalence in shiftworks. Interventional, one cross-sectional and three cohort studies showed higher frequency of meal intake or poor nutrition quality/habits in the shift workers compared with the day-shift workers. Another cross-sectional study showed no difference between workers. CONCLUSION: In terms of obesity or high BMI, majority of cross-sectional studies indicate that shiftwork increases weight gain and the prevalence of obesity. On the other hand, half of cohort studies show higher frequency of meal intake and/or poor nutrition quality in the shift workers. Generally, it is indicated that shift working negatively impacts on health and nutritional status of workforces.