Vitamin D is essential to the treatment of osteoporosis because it promotes calcium absorption from the diet and is necessary for normal bone growth. Some research suggests it may also ward off immune diseases, infection and cancer.

The new guidelines recommend daily supplements of 400 to 1000 IU for adults under age 50 without osteoporosis or conditions affecting vitamin D absorption. For adults over 50, supplements of between 800 and 2000 IU are recommended.

"A daily supplement of 25 mcg (800 IU) should now be regarded as a minimum dose for adults with osteoporosis," writes Hanley with co-authors. "Canadians can safely take daily vitamin D supplements up to the current definition of tolerable upper intake level (50 mcg [2000 IU]), but doses above that require medical supervision."

The authors conclude with a call for research into optimal doses and safe upper limits for vitamin D intake. Despite a great deal of new research in the past decade, these major clinical questions still have not been addressed.

Source: University of Calgary