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 abstracts, 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 nutritional/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.