assumption can create some problems for compliance and therapy adhesion,have randomized 2317 women (averagely 76 years of age) with a high fracture risk to receive only one annual dose of vitamin D (500,000 UI) or placebo, for averagely 3-5 years. All women having already taken vitamin D or undergoing other preventive therapies against fractures have been excluded from the trial. Most participants besides took a supplementation of calcium of at least 800 mg. Blood levels of 25-OH-D at the beginning of the trial were about 20 ng/ml. Measured after 1 month, 3 months and 1 year from vitamin D administration, they were
found increased respectively of 2.4 times, of 1.8 times and of twice in treated women compared with the placebo group. During the three year of treatment, the fracture rate has been higher in the group treated with
vitamin than in the placebo group (5 fractures/100 women/year vs. 4; p=0.047). Falls too have been more frequent in the treated group (83 falls/100 women/year vs. 73; p=0.03).The results of this trial are really amazing: the similarity between increase in the number of falls and increase in the fractures would suggest a dose-dependent relation between the administration of vitamin and the fracture risk, but it is not possible to explain such a finding.It is however interesting to note that another trial too, published on Rheumatology (2007; 46:1852), has marked an increase in hip fracture risk after vitamin D supplementation. So, if one wants to give vitamin Din bone prevention, it is better to avoid the practice of annual administration.
