Written by Marcia J. Egles, MD. Supplementing with Vitamin D reduced nonvertebral fractures by 20% and hip fractures by 18%. 

Over the past few years, several clinical trials have questioned the benefits of vitamin D in fracture prevention (1,2,3,4).  Other studies have supported its use (5,6,7 ). A recent statistical review study has sought to clarify this seemingly contradictory tangle of information by carefully sorting the data according to the vitamin D dosages used in these trials.  The new study found that the success of fracture prevention with vitamin D supplements depends on the amount of vitamin D used. Oral vitamin D supplements given in a dose of more than 400 international units (IU) per day were shown to reduce the risk of nonvertebral bone fractures in older adults. Nonvertebral fractures are broken bones in places other than the spine.

Collectively, the clinical trials concerning vitamin D and fracture prevention represent an enormous effort in public health. In the hierarchy of medical research, the “randomized controlled clinical trial” is at the top. It provides the  best and most reliable data in humans as compared to other types of studies. A randomized controlled clinical trial goes beyond the observation of “links” or “associations” which are the limits of lesser studies. It seeks to find what causes something. These trials can be massive undertakings with thousands of participants involved for several years or longer.

Through a systematic review of the medical literature and an analysis of high quality,  randomized controlled clinical trials, the new study assessed the antifracture efficacy of oral vitamin D supplementation in persons 65 years or older.  Twelve previously reported randomized controlled clinical studies for nonvertebral fractures, including eight studies specifically for hip fractures, were included. The participants in these trials totaled 42,279 persons. When the fracture data was pooled, no fracture reduction was observed for a received dose of 400 IU per day  or less. However, a higher dose of 482 to 770 IU per day of supplemental vitamin D reduced nonvertebral fractures by 20% and hip fractures by 18%.

The researchers concluded from the combined clinical trials that nonvertebral fracture prevention with vitamin D is dose dependent. An appropriate dose should reduce nonvertebral fractures by at least 20% for individuals aged 65 years or older.

Source: Bischoff-Ferrari, Heike A., et al. “Prevention of nonvertebral fractures with oral vitamin D and dose dependency: a meta-analysis of randomized controlled trials.” Archives of internal medicine 169.6 (2009): 551-561.

©2009 American Medical Association. All rights reserved.

Posted April 14, 2009.

References:

  1. Porthouse J, Cockayne S, King C; et al. Randomised controlled trial of calcium and supplementation with cholecalciferol (vitamin D3) for prevention of fractures in primary care. BMJ. 2005;330(7498):1003.
  2. Grant 2. AM, Avenell A, Campbell MK; et al. Oral vitamin D3 and calcium for secondary prevention of low-trauma fractures in elderly people (randomised evaluation of calcium or vitamin D, RECORD): a randomised placebo-controlled trial. Lancet. 2005;365(9471):1621-1628.
  3. Jackson RD, LaCroix AZ, Gass M; et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med. 2006;354(7):669-683.
  4. Lyons RA, Johansen A, Brophy S; et al. Preventing fractures among older people living in institutional care: a pragmatic randomised double blind placebo controlled trial of vitamin D supplementation. Osteoporos Int. 2007;18(6):811-818.
  5. Bischoff-Ferrari HA, Dietrich T, Orav EJ, Dawson-Hughes B. Higher 25-hydroxyvitamin D concentrations are associated with better lower-extremity function in both active and inactive persons aged greater than 60 y. Am J Clin Nutr. 2004;80(3):752-758.
  6. Wicherts IS, van Schoor NM, Boeke AJ; et al. Vitamin D status predicts physical performance and its decline in older persons. J Clin Endocrinol Metab. 2007;92(6):2058-2065.
  7. Bischoff-Ferrari HA, Willett WC, Wong JB, Giovannucci E, Dietrich T, Dawson-Hughes B. Fracture prevention with vitamin D supplementation: a meta-analysis of randomized controlled trials. JAMA. 2005;293(18):2257-2264.