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

BACKGROUND: Reported cases of vitamin D3 deficiency have been increasing in incidence worldwide. Although there is a lack of consensus relating to optimal levels of vitamin D, generally serum 25-(OH)D concentrations lower than 50 nmol/L (20 ng/mL) are at least considered to be detrimental to bone health. AIM: Aim of this systematic review is to investigate if occupations, and specifically shiftworking and indoor working, may be considered as possible contributors to the increased incidence of vitamin D3 deficiency in industrialized nations. MATERIALS AND METHODS: Systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement using PubMed, Scopus, and ISI Web of Knowledge databases. RESULTS: Overall 90 papers were found, 23 articles through PubMed, 30 through Scopus, and 37 through ISI Web of Knowledge. Successively, 46 duplicates and 34 articles that did not respect the inclusion criteria were excluded. Finally 10 articles were selected: 9 cross-sectional studies and 1 systematic review. Results of the studies included revealed that certain occupations are either suffering from, or have a predilection to suffer from, a deficiency of this vitamin. Shiftworkers and indoor workers are consistently reported as being the occupational group most likely to suffer from a deficiency of vitamin D3. It would appear prudent to investigate the potential of providing nutritional education to workers in addition to including preventative measures in the workplace.