High-dose vitamin D may harm bone health
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.
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 10,000 IU.