Due to little outdoor activity and low dietary intake of vitamin D (VD), Bangladeshi low-income women are at risk for osteoporosis at an early age. The present study assessed the effect of VD, Ca and multiple micronutrient supplementation on VD and bone status in Bangladeshi young female garment factory workers. This placebo-controlled 1-year intervention randomly assigned 200 apparently healthy subjects (aged 16–36 years) to four groups: VD group, daily 10 μg VD; VD and Ca (VD-Ca) group, daily 10 μg VD+600 mg Ca; multiple micronutrient and Ca (MMN-Ca) group, 10 μg VD and other micronutrients+600 mg Ca; a placebo group. Serum 25-hydroxyvitamin D (S-25OHD), intact parathyroid hormone (S-iPTH), Ca, phosphate and alkaline phosphatase were measured. Bone mineral density and bone mineral content were measured by dual-energy X-ray absorptiometry. All measurements were made at baseline and at 12 months. Significantly (P < 0·001) higher S-25OHD concentrations were observed in the supplemented groups than in the placebo group after the intervention. Supplementation had an effect (P < 0·001) on S-iPTH in the VD-Ca and MMN-Ca groups compared with the placebo group. Bone mineral augmentation increased at the femur in the supplemented groups. Supplementation with VD-Ca should be recommended as a strategic option to reduce the risk of osteomalacia and osteoporosis in these subjects. MMN-Ca may have analogous positive health implications with additional non-skeletal benefits.

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.