Impact of ultraviolet radiation on bone density and muscle strength in postmenopausal women: a randomized controlled study.

OBJECTIVE: This study aimed to evaluate the effects of narrowband ultraviolet B (UVB) irradiation on bone and muscle health in postmenopausal women. METHODS: A randomized controlled trial was conducted involving 70 postmenopausal women with vitamin D deficiency (<20 ng/mL) and osteopenia. Participants were randomly assigned to two groups. For 6 months, 35 postmenopausal women in study group A received three weekly sessions of narrowband UVB therapy and vitamin D supplements in the form of 100,000 international unit (IU) cholecalciferol weekly as loading therapy for 8 weeks. This was followed by the daily administration of cholecalciferol 3,000 IU as maintenance therapy for 16 weeks. The control group B consisted of 35 postmenopausal women who were administered vitamin D supplements alone for 6 months. Enzyme-linked immuno sorbent assay kits were used to test the serum levels of 25-hydroxyvitamin D (25(OH)D), dual-energy X-ray absorptiometry (DEXA) (DMS, Occitanie, France) was used to test the bone mineral density of the lumbar spine and right femur, and a Biodex System 3 (Biodex Medical Systems Inc., Shirley, NY, USA) isokinetic dynamometer was used to assess the peak torque of the extensors and flexors of the dominant knee. RESULTS: Serum 25(OH)D levels (P=0.000), Lumbar T-score (P=0.008), femoral T-score (P=0.002), and knee extensor peak torque (P=0.030) significantly increased in both groups after 6 months of treatment, favoring study group A over the control group B. CONCLUSION: Narrowband UVB combined with vitamin D3 supplementation is more effective than vitamin D supplementation alone.