In Summary, for those who took the Vitamin D supplements:

Benefits in NNT

  • 97.2% saw no benefit
  • 2.8% were helped by preventing a hip fracture
  • 1 in 36 were helped (hip fracture prevented)

Harms in NNT

  • 2.8% were harmed by kidney stones or kidney damage
  • 1 in 36 were harmed (kidney stones, kidney damage)

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Source: Avenell A, Gillespie WJ, Gillespie LD, O’Connell D. Vitamin D and vitamin D analogues for preventing fractures associated with involutional and post-menopausal osteoporosis. In: Avenell A, with The Cochrane Collaboration, eds. Cochrane Database of Systematic Reviews.
Sanders KM, Stuart AL, Williamson EJ, et al. Annual High-Dose Oral Vitamin D and Falls and Fractures in Older Women. JAMA: The Journal of the American Medical Association. 2010;303(18):1815 -1822.
Bolland MJ, Grey A, Avenell A, Gamble GD, Reid IR. Calcium supplements with or without vitamin D and risk of cardiovascular events: reanalysis of the Women’s Health Initiative limited access dataset and meta-analysis. BMJ. 2011;342:d2040.

Efficacy Endpoints: Prevention of fractures

Harm Endpoints: Kidney stones, kidney damage

Narrative: Vitamin D increases the absorption of calcium in the intestine and has a role in maintaining bone density. Sources of Vitamin D are limited other than exposure of the skin to ultraviolet light (sunlight) which stimulates Vitamin D production. Some authorities suggest Vitamin D as a supplement in the hopes that it might lead to reductions in fractures by increasing bone strength. The Cochrane review summarized here examined two large trials with >3850 elderly, institutionalized subjects.

In frail, elderly individuals in institutional settings there was a small reduction in hip fractures, which is an important and dreaded injury for a variety of reasons. The NNT for avoiding a hip fracture in this group group [164/2023 (8.1%) vs 199/1830 (10.9%)] was approximately 36.

There does appear to be consistent harm associated with Vitamin D, in the form of an increase in kidney problems, either kidney stones or renal insufficiency. The NNH for this was [453/22529 for 20.1% versus 388/22449 for 17.3%] 36.

Caveats: In community dwelling adults in trials there was no benefit. There are recent data to suggest that Vitamin D supplementation may increase falls and fractures though this was in non-institutionalized persons,1 and calcium supplementation has recently been implicated in heart attacks among post-menopausal women. The benefit noted here for institutionalized elderly patients was recorded in two different trials, both performed at the same institution in France, and the Cochrane authors point out that this should be confirmed in other settings before it is widely accepted as accurate.2

However, the avoidance of hip fractures is immensely important. While the prospect of kidney damage or stones and the hints of cardiac problems may turn out to be significant in future studies, hip fractures are known to be very painful and can lead to major changes in levels of independence and overall health. Thus until proven otherwise we believe that the current state of evidence supports the use of Vitamin D combined with calcium supplementation for the institutionalized elderly, and have classified this as a ‘GREEN’ intervention.

Author: David Newman, MD

Published/Updated: May 15, 2011

  1. The Title Bar

    The title bar is color-coded with our overall recommendation.

    • Green: Benefits outweigh risks.
    • Yellow: Unclear risk/benefit profile.
    • Red: Benefits do not outweigh risks.
    • Black: Obvious harms, no clear benefits.
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