12 January - 20 June 2016

Should vitamin D guidelines consider occupation?

A study by Sowah et al. published in BMC Public Health has investigated serum vitamin D levels and insufficiency and deficiency in different occupational groups, to identity those workers at particular risk of vitamin D deficiency or insufficiency.

Last year the EFSA set dietary reference values (DRVs) for the intake of vitamin D.  The Panel on Dietetic Products, Nutrition and Allergies (NDA) defined an adequate intake (AI) of 15 µg per day for healthy individuals over one year of age. This includes pregnant and lactating women. The DRVs for infants aged 7-11 months have been set at 10 µg per day.

A study by Sowah et al. published in BMC Public Health has investigated serum vitamin D levels and insufficiency and deficiency in different occupational groups, to identity those workers at particular risk of vitamin D deficiency or insufficiency. 

The scientists conducted a systematic review of 71 peer reviewed journal articles involving at least 53,345 participants in total.  The studies included outdoor and indoor workers, shiftworkers, lead/smelter workers, coalminers and healthcare professionals who spanned a range of latitudes in both the Northern and Southern hemisphere.  Studies were excluded if they included participants who were 18 and under, or 65 and older as these participants were assumed to not be in employment.

After analysis, the researchers report that prevalence of vitamin D deficiency was highest amongst shift workers (80% of individuals), followed by indoor workers (78%) and healthcare students (72%). 

Sowah et al. report  mean vitamin D levels were significantly lower in indoor/office workers compared to outdoor workers ( 40.6 ± 13.2 nmol/L vs  66.6 ± 16.7 nmol/L) with shiftworkers having the  lowest average levels of serum vitamin D (33.8 ± 10.1 nmols/L).  Shiftworkers were also found to have the highest risk of developing vitamin D deficiency and insufficiency. 

Lead/smelter workers had the highest vitamin D levels among all occupational categories (77.8 ± 5.4 nmol/L).   With none of the studies included (5 studies of 183 participants) reporting data on the proportion of participants who were either vitamin D deficient or insufficient.  

Three studies with a total of 314 participants investigated coalminers.  The scientists divided the participants into two groups, those who worked underground and those who worked on the surface to examine whether type of mining had an impact on vitamin D status.  They report there was no significant difference in average vitamin D levels between underground and surface miners (57.8 ± 11.7 vs 52.4 ± 12.4 nmol/L). 

Thirty five studies investigated vitamin D deficiency in healthcare workers (total of 19083 study participants).  The study found a variation between subgroups with medical residents and healthcare students having the lowest levels of circulating vitamin D (44.0 ± 8.3 nmol/L (65% deficient) and 45.2 ± 5.5 nmol/L respectively (72% deficient), practicing physician (46% deficient), nurses 43%) or other healthcare professionals (43%).

In a press release Dr. Sebastian Straube, the corresponding author said: "Our results suggest that occupation is a major factor that may contribute to suboptimal vitamin D levels. Regular screening of vitamin D levels in at-risk groups should be considered for future clinical practice guidelines and public health initiatives. Workplace wellness programs could include education about the importance of adequate vitamin D levels. This could help prevent adverse health outcomes linked to vitamin D deficiency, such as metabolic disorders, psychiatric and cardiovascular disorders, and cancer."

The authors conclude by stating “individuals who work predominantly indoor and shift workers are at risk of developing vitamin deficiency or insufficiency.” They continue by stating that future studies are needed but suggest that “guidelines on screening for vitamin D deficiency and supplementation strategies in vulnerable groups should include consideration of occupation.”  They do note the limitation of their study including the lack of agreement on the definition of vitamin D deficiency, different methodologies for assessing vitamin D levels, and studies taking place at different latitudes, although they did find that vitamin D deficiency or insufficiency did not seem to be dependent on study location.

RSSL provides vitamin analysis in a wide range of matrices including drinks, fortified foods, pre-mixes and multi-vitamin tablets, including the analysis for Vitamin D2 and Vitamin D3.  For more information please contact Customer Services on +44 (0) 118 918 4076 or email enquiries@rssl.com

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