High-dose vitamin D may harm bone health

Doses at or above 4000 IU/day lowered volumetric bone density: study

Higher doses of vitamin D in healthy adults who aren't vitamin D deficient don't improve bone health and may actually be harmful, according to a Canadian trial.

bone density

The randomised controlled trial in JAMA assessed the effect of vitamin D supplementation on volumetric bone mineral density and strength in 311 healthy adults (53 men; mean age 62) without osteoporosis.

They had baseline 25-hydroxyvitamin D levels of 30-125nmol/L. For three years, participants took daily doses of vitamin D3 of 400 IU, 4000 IU or 10