Are Shiftwork and Indoor Work Related to D3 Vitamin Deficiency? A Systematic Review of Current Evidences

Table 1

Characteristics of cross-sectional study.

First author	Country	Year	Study design	Sample	Main results	Type of work	NOS (max 9)
Ward	UK	2011	Cross-sectional study	6134	An association between night work and 25(OH)D concentrations found in women; concentrations 8% lower (95% CI 15% to 2%) in night workers compared with others	Various	7
Itoh	Japan	2011	Cross-sectional study	19	Seasonal variation in circulating 25(OH)D and intact PTH levels, and hypovitaminosis D in wintertime in indoor daytime male workers in Japan	Healthy indoor daytime workers	7
Itoh	Japan	2011	Cross-sectional study	12	Seasonal difference in 25(OH)D between the months of February and October 2008 in indoor daytime workers intact PTH circulating levels were high in February and decreased in October, while no consistent pattern of seasonal variation in 1α, 25(OH)2D	Healthy indoor worker	7
Wallingford	USA	2013	Cross-sectional study	83	Most nurses had adequate serum vitamin D status for bone health, 13% were at risk for osteoporosis and/or osteomalacia following winter months	Premenopausal nurses	8
Jeong	Korea	2014	Cross-sectional study	5409	Permanent workers (84.7%) showed a higher prevalence of vitamin D deficiency compared to the temporary workers (78.8%). The prevalence of vitamin D deficiency among the office workers was 88.1%, higher than that of the manufacturing workers (79.0%)	Indoor worker	7
Romano	Italy	2015	Cross-sectional study	196	Shiftworkers had lower levels of vitamin D (Wilcoxon–Mann–Whitney test, )	Shift workers at an engineering factory and daily workers operating nearby	7
Mizoue	Japan	2015	Cross-sectional study	1786	Low 25(OH)D concentrations more frequent in young, female, and smokers engaged in shiftwork and overtime work and slept less	Employees of a manufacturing company in the nonferrous metal industry	7
Alefishat	Jordan	2016	Cross-sectional study	140	Female night workers had significantly lower serum 25(OH)D levels compared to the female day workers (). No significant difference in serum 25(OH)D levels was found between the night and day male workers (). The number of night shifts/month was negatively correlated with 25(OH)D levels in both the males and females ( and )	Night shift worker	8
Lenhert	Germany	2018	Cross-sectional study	67	Lower serum levels were found in samples drawn in winter and spring and in obese subjects. Shiftwork had only small effects on vitamin D levels	Female health care worker	8