High-Dose Vitamin D Might Reduce Bone Mineral Density

High-dose vitamin D supplements don’t appear to improve bone mineral density in healthy adults and may even have a negative impact, according to a JAMA study.

Some 300 healthy adults aged 55 to 70 years were randomized to receive 400, 4000, or 10,000 IU of oral cholecalciferol daily for 3 years.

Higher dose vitamin D (10,000 IU and 4000 IU) was associated with greater bone mineral density loss at the radius than 400 IU daily (-7.5 and -3.9 mg hydroxyapatite/cm₃, respectively). The 10,000-IU dose, but not the 4000-IU dose, was also associated with significant reductions at the tibia. Patients receiving higher doses were at higher risk for hypercalcemia and hypercalciuria. Bone strength didn’t differ among groups.

The authors conclude: “These findings do not support a benefit of high-dose vitamin D supplementation for bone health; further research would be needed to determine whether it is harmful.”