IHN Database

Supplementary vitamin D may prevent fractures

BOSTON, MASSACHUSETTS. Bone fractures in older people are a significant cause of mortality and ill- health, with rates set to increase with the aging population. Hip fractures are particularly widespread, and lead to permanent disability in approximately 50 per cent of patients.

One prevention strategy, which has been suggested, is supplementing with vitamin D. It has been examined in several studies and a team from Harvard School of Public Health has analyzed the findings so far. They used rigid rules to select 14 reliable studies of oral vitamin D supplement (using cholecalciferol [vitamin D3]) against placebo on hip and non-vertebral fractures in people over 60 years of age. In total, this included 9,294 participants in hip fracture studies and 9,820 in studies of non-vertebral fractures. The average age of participants was 79 years, and two-thirds were female. The trials using low-dose (400 IU/d) and higher-dose vitamin D (700-800 IU/d) were analyzed separately. The higher dose lowered hip fracture risk by 26 per cent and overall non-vertebral fracture by 23 per cent. No benefit was found for the lower dose. Results suggest that for every 45 people taking the higher dose, one hip fracture could be avoided, and for every 27 people one non-vertebral fracture could be avoided. The duration of supplementation did not alter fracture rates, possibly due to the rapid effects of vitamin D found previously. The mechanisms which lie behind the benefit may be reductions in bone loss and increases in muscle strength and balance, all of which reduce fall risk. However, calcium was also given in many of the trials and may have influenced fracture rates.

The authors conclude that vitamin D at 700-800 IU per day should reduce fracture rates by about a quarter. They believe that a compelling case has been made for general vitamin D supplementation in older people. They also conclude that the currently recommended daily intake of 400 IU is inadequate to prevent fractures. A high intake of calcium may also be necessary and should be investigated further, as should even higher doses of vitamin D and the interaction between the two nutrients.
Bischoff-Ferrari, H.A. et al. Fracture Prevention with Vitamin D Supplementation A Meta-analysis of Randomized Controlled Trials. Journal of the American Medical Association, Vol. 293, May 2005, pp. 2257-2264

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