Effect of four monthly oral vitamin D3 (cholecalciferol) supplementation on fractures and mortality in men and women living in the community: randomised double blind controlled trial

Randomised double blind controlled trial.

Link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC150177/

From conclusion:

"Four monthly supplementation with 100 000 IU oral vitamin D may prevent fractures without adverse effects in men and women living in the general community."