Effect of underground working on vitamin D levels and bone mineral densities in coal miners: a controlled study.

The aim of this study was to determine the effect of underground working on 25-hydroxyvitamin D (25-OHD) levels and bone mineral density (BMD) values in coal miners. Fifty coal miners working underground and 50 surface workers as controls, matched for age and body mass index, from Zonguldak, Turkey, were recruited to the study. Levels of 25-OHD, biochemical bone markers, and lumbar spine and femur BMD values were measured in all study participants. Lumbar spine and femur BMD values were significantly higher in underground workers compared with surface workers, but there was no significant difference in 25-OHD levels between the two groups. Duration of underground working, age, 25-OHD levels, cigarette consumption and dietary calcium intake were not correlated with BMD values. Underground physical working does not seem to be a significant risk factor for low 25-OHD levels or low BMD values.