Vitamin D deficiency and low bone status in adult female garment factory workers in Bangladesh

Abstract

The manufacture of garments is the main industry in Bangladesh and employs 1.6 million female workers. Due to the indoor lifestyle and low dietary intake of calcium, we hypothesised that they are at risk of low vitamin D and bone mineral status. Two hundred female garment workers (aged 18-36 years) were randomly selected. Serum 25-hydroxyvitamin D (S-25OHD), serum intact parathyroid hormone (S-iPTH), serum calcium (S-Ca), serum phosphate (S-P) concentration and serum alkaline phosphatase activity (S-ALP) were measured from fasting samples. Bone indexes of hip and spine were measured by dual-energy X-ray absorptiometry. The mean S-25OHD (36.7 nmol/l) was low compared to that recommended for vitamin D sufficiency. About 16 % of the subjects were found to be vitamin D-deficient (S-25OHD < 25 nmol/l). We observed a high prevalence (88.5 %) of vitamin D insufficiency (S-25OHD < 50 nmol/l) as well as a significant inverse relationship between S-25OHD and S-iPTH (r -0.25, P ≤ 0.001). A decrease in S-25OHD (< 38 nmol/l) and an increase in S-iPTH (>21 ng/l) was associated with progressive reduction in bone mineral density at the femoral neck and lumbar spine. According to the WHO criteria, the mean T-score of the femoral neck and lumbar spine of the subjects were within osteopenic range. We observed that subjects with a bone mineral density T-score < -2.5 had a trend of lower values of BMI, waist-hip circumference, mid-upper-arm circumference, S-25OHD and higher S-iPTH and S-ALP. The high prevalence of hypovitaminosis D and low bone mineral density among these subjects are indicative of higher risk for osteomalacia or osteoporosis and fracture. © The Authors 2008.