Heike A. Bischoff-Ferrari, DrPH et al, have just published an important study on Vitamin D and fractures in older women, in the prestigious Archives of Internal Medicine,

These doctors reviewed 12 different medical studies that included more than 65,000 subjects, all over the age of 65. The findings are that doses of Vitamin D OVER 400 IU per day reduce hip fractures in women living in the community by 29% and women in institutions (eg nursing homes) by 15%. Of note is that these results, with higher than 400IU of Vitamin D were independent of adding more calcium. No benefit for fracture prevention was found in the commonly used dose of 400 IU per day that is in most over the counter Calcium supplements.  

The "higher doses" in this study were only 482 to 770 IU per day of additional vitamin D. The authors go on to recommend that further studies with even higher doses of vitamin D (as I recommend in my book) should be done to see if the higher levels of vitamin D will further decrease the fracture rates. This type of study still has not been started.

 
As I discuss in my book, this study also gives the suggestion that vitamin D3 seemed to be more effective than vitamin D2.  This is currently being hotly discussed in the medical literature. Two studies have shown that vitamin D3 is more effective than vitamin D2, and one study has shown that they are similarly effective.

As my readers know, I recommend a basic dose of 2000 IU of Vitamin D3 per day in otherwise healthy people. One can only wonder how much better for preventing fractures this dose might be?  Lets get the studies going, but in the mean time it never hurts to normalize your vitamin D blood level!

Ref: Arch Intern Med. 2009;169(6):551-561