A month ago, the press was full of stories covering the U.S. Preventive Services Task Force (USPSTF) draft recommendation that low-dose vitamin D (400 IU or less) does not help prevent fractures. The headline writers covering the previous USPSTF statement about low dose vitamin D and fractures wrote something to the tune of, “Vitamin D doesn’t help” or something even more misleading:
Confusingly, the same agency says vitamin D prevents falls. How can it prevent falls but not prevent fractures? The two so often go together. In fact, 5 to 10% of all falls will lead to fracture.
Virginia A. Moyer, MD, MPH, on behalf of the U.S. Preventive Services Task Force. Prevention of Falls in Community-Dwelling Older Adults: U.S. Preventive Services Task Force Recommendation Statement. Ann Intern Med. 29 May 2012
In a timely fashion, a new meta-analysis confirms what we all know: the problem is dose. 400 IU/day will not prevent much of anything. This new study in the New England Journal of Medicine has shown that higher dose vitamin D (800 to 2,000 IU) does indeed prevent fractures. They also warned against taking more than 1,000 mg of calcium a day (from all sources, foods and supplements).
Heike A. Bischoff-Ferrari, M.D., Dr.P.H., Walter C. Willett, M.D., Dr.P.H., Endel J. Orav, Ph.D., Paul Lips, M.D., Pierre J. Meunier, M.D., Ronan A. Lyons, M.D., M.P.H., Leon Flicker, M.D., John Wark, M.D., Ph.D., Rebecca D. Jackson, M.D., Jane A. Cauley, Dr.P.H., Haakon E. Meyer, M.D., Ph.D., Michael Pfeifer, M.D., Kerrie M. Sanders, Ph.D., Hannes B. Stähelin, M.D., Robert Theiler, M.D., and Bess Dawson-Hughes, M.D. A Pooled Analysis of Vitamin D Dose Requirements for Fracture Prevention. N Engl J Med 2012; 367:40-49J
Long story short: take high dose vitamin D to prevent both falls and fractures, about 5,000 IU/day, along with its cofactors, magnesium, zinc, boron, and vitamin K2, and no more than a total of 1,000 mg of calcium a day. Given the effect of vitamin D on calcium absorption, I personally think 800 mg of calcium (from all sources) is just fine, but know of no study to back that up.