Plenty of vitamin D helps prevent hip fractures in old age

The risk of suffering a hip fracture increases continuously from the age of 65 because our bones become weaker and more fragile the older we get. A study sponsored by the Swiss National Science Foundation (SNSF) has shown that vitamin D helps to prevent hip fractures, albeit only in high doses (800 units or more per day).

Healthy bones regenerate by absorbing calcium and phosphate continuously with the help of vitamin D. In the absence of vitamin D, bones become brittle. This often happens in old age, when the skin starts to lose its ability to produce vitamin D from the energy in sunlight. This is why three-quarters of all fractures occur in people over the age of 65. This age category is growing fast in Europe, and we are likely to see the number of hip fractures double by 2050.

Conflicting results
Several clinical trials have looked at whether the number of hip fractures and the horrendous costs associated with them can be reduced by administering prophylactic vitamin D. The results have been inconsistent. Researchers working with Heike Bischoff-Ferrari from the Centre on Ageing and Mobility at Zurich University have now produced a new overview of the data. Their meta-analysis(*), published recently in the New England Journal of Medicine, manages to resolve the contradictions.
Bischoff-Ferrari and her colleagues at Zurich University Hospital and Waid City Hospital looked at the original data generated from slightly over 30,000 elderly people who had taken part in eleven different clinical trials of vitamin D supplementation. Theirs was the first analysis to take account of the fact that some people had taken fewer vitamin D drops than intended while others had taken additional vitamin D outside the clinical trial.

Disputed dose-effect relationship
The group working with Bischoff-Ferrari demonstrated a dose-effect relationship that had hitherto been disputed. They found that vitamin D only has a protective effect if it is taken in large enough quantities. The risk of a hip fracture was thirty percent lower in people who had taken at least 800 international units (IU) of vitamin D every day.
This dosage level benefits both fragile senior citizens and those who are in good health and still living at home. “At the moment, our study is the most significant evidence base supporting the high dosage for elderly individuals recommended by the Federal Office of Public Health,” Bischoff-Ferrari commented.

(*)Heike A. Bischoff-Ferrari, Walter C. Willett, Endel J. Oray, Paul Lips, Pierre J. Meunier, Ronan A. Lyons, Leon Flicker, John Wark, Rebecca D. Jackson, Jane A. Cauley, Haakon E. Meyer, Michael Pfeifer, Kerrie M. Sanders, Hannes B. Stähelin, Robert Theiler and Bess Dawson-Hughes (2012). A Pooled Analysis of Vitamin D Dose Requirements for Fracture Prevention. New England Journal of Medicine 367: 40-49.
(Available as a PDF from the SNSF; E-mail: com@snf.ch)

Contact
Prof. Heike Annette Bischoff-Ferrari, MD
Zentrum Alter und Mobilität
Rheumaklinik, Universitätsspital Zürich
Gloriastrasse 25
CH-8091 Zürich
Tel.: +41 (0)44 255 26 99
E-mail: heike.bischoff@usz.ch