Office, workshop workers at high risk for vitamin D deficiency

Office and workshop workers were at a greater risk for vitamin D deficiency compared with control room workers, according to a recent Singapore study.

“Little is known about the effect of working conditions on vitamin D status in Southeast Asia, where vitamin D deficiency is common despite the presence of sunlight all year round in most places,” said the researchers.

A previous study reported that 90 percent of the vitamin D is synthesized in the skin upon exposure to ultraviolet B (UV-B) radiation from sunlight, while 10 percent is obtained from food such as oily fish, egg yolks, fortified milk and juices, and dietary supplements. [J Clin Endocrinol Metab 2011;96:1911-1930]

The researchers analysed 213 participants (mean age 42.5 years, 76.5 percent male) who were office (n=109), workshop (n=50), and control room workers (n=54) from four workplaces in Singapore between August 2016 and January 2017. Blood samples were collected for determination of serum 25-hydroxyvitamin D [25(OH)D] concentration to assess vitamin D status. Self-administered questionnaires were given to evaluate work-related factors and other covariates. At the time of data collection, the UV index value in Singapore was ~7.5 (high). Subjects were followed up at 3 and 12 months. [Int J Environ Res Public Health 2020;17:164]

Results showed that the overall prevalence of vitamin D deficiency* was at 32.9 percent, which was considered lower than the general population of Singapore at 42.1 percent.

In a multivariate analysis, a significantly higher risk of vitamin D deficiency was observed among workers in the office (prevalence ratio [PR], 2.16, 95 percent confidence interval [CI], 1.12–4.16; p=0.021) or workshop (PR, 2.25, 95 percent CI, 1.05–4.81; p=0.037) than those in the control room.

In addition, those who worked on night shift (median, one-night shift per month) showed a significantly increased risk of vitamin D deficiency (PR, 1.31, 95 percent CI, 1.03–1.67; p=0.027). “Night shift workers, due to their working hours and daytime sleeping, are generally exposed less to solar UV-B radiation,” the researchers noted.

“Other work-related factors[, particularly working hours per day,] were not significantly associated with vitamin D deficiency, … [which is in contrast to previous studies, wherein] those who work for long hours indoors are likely to have low sunlight exposure, and thus are more prone to vitamin D deficiency,” the researchers said. [Br J Nutr 2013;109:493-502; Occup Environ Med;2011;68:902-907]

The researchers noted that the study has some limitations, including the small sample size with limited power to detect a significant difference between the association of working hours and vitamin D deficiency.

“[In conclusion,] office and workshop workers (vs control room workers) and night shift workers were at a higher risk for vitamin D deficiency,” the researchers said, who suggested that “workplace policies and wellness program[me]s should incorporate regular screening program[me]s for vitamin D in office, workshop, and night shift workers.”

“Workers[, especially those doing night shift,] should [also] be encouraged to take breaks to go outdoors for sunlight exposure and to consume adequate amounts of vitamin D-rich food to maintain optimal vitamin D levels, although the role of supplements remains controversial,” said the researchers.

“Future studies with larger sample size are required to confirm our study findings,” they added.