What Dose of Vitamin D is Most Effective?

The most beneficial dose of vitamin D supplementation needed to reduce fall risk has not been established. Douglas P. Kiel, M.D., associate professor of medicine at Harvard Medical School in Boston and the director of medical research at the Boston-based Hebrew Senior Life center, studied 125 nursing home residents with an average age of 89. There were no baseline differences across the participants, except for their age. Participants either received a placebo, 200 international units, 400 international units, 600 international units or 800 international units of vitamin D. Dr. Kiel and his colleagues found those getting 800 international units of vitamin D had a 71-percent reduction in risk of falls compared with those getting lower doses or placebo. And compared to the participants receiving 800 international units of vitamin D, the other four groups had a three- to four-fold increase in the hazard ratio for a fall.

Dr. Kiel concludes to achieve maximum benefit in the nursing home setting, vitamin D doses of 800 international units or higher may be needed.