The influence of smoking on vitamin D status and calcium metabolism

To assess the influence of smoking on serum parathyroid hormone (PTH), serum vitamin D metabolites, serum ionized calcium, serum phosphate, and biochemical markers of bone turnover in a cohort of 510 healthy Danish perimenopausal women. A cross-sectional study. Copenhagen, Denmark. Five-hundred-and-ten healthy women aged 45-58 y, included 3-24 months after last menstrual bleeding. None were using hormone replacement therapy. The women were grouped according to their current smoking status. The two groups were compared with regard to serum levels of 25-hydroxyvitamin D (25OHD) and 1, 25-dihydroxyvitamin D (1,25-(OH)2D), intact PTH, ionized calcium and phosphate, osteocalcin, as well as urine pyridinolines. Bone mineral density (BMD) was measured with DEXA-scans. Multiple regression analyses were performed to detect the effect of potentially confounding lifestyle factors, such as calcium and vitamin D intakes, alcohol and coffee consumption, sunbathing, and physical exercise. Fifty percent were current smokers. Smokers had significantly reduced levels of serum 25OHD (P=0.02), 1,25(OH)2D (P=0.001), and PTH (P