80%) compliance rates. Calcium doses 1200 mg daily were more effective than
lower doses. Adding vitamin D to calcium conferred no additional benefit.
Results from a meta-analysis indicate that it does.
Results from clinical trials and meta-analyses have been inconsistent regarding the efficacy of calcium in preventing fractures. Investigators expanded on previous results by conducting a systematic review of data from all randomized trials published from 1966 through 2006 that compared calcium (with or without vitamin D) and placebo in adults older than 50. They identified 29 studies involving 63,897 patients (92% women; mean age, 67.8) who were treated for an average of 3.5 years.
In an analysis of 17 trials that reported fracture as an outcome,
calcium supplementation (with or without vitamin D) was associated with a
significant 12% relative risk reduction in all fractures. In an analysis of 24
trials that reported bone-mineral density, calcium use significantly reduced the
rate of bone loss at the hip and spine. The reduction in fracture risk increased
with age and reached statistical significance after age 70. The treatment effect
was greater in institutionalized people and in those with low body weight or low
calcium intake, compared with their counterparts. Risk reduction doubled in
trials with high (80%) compliance rates. Calcium doses 1200 mg daily were more effective than
lower doses. Adding vitamin D to calcium conferred no additional benefit.
Comment: The authors estimate that 63 patients would need to be treated for 3.5 years to prevent one fracture, but the number would be below 30 in some high-risk subgroups. Until we have detailed prospective data to provide further guidance, it seems reasonable to recommend daily supplementation with at least 1200 mg of calcium for most patients older than 70.
Published in Journal Watch General Medicine September 20, 2007
Tang BMP et al. Use of calcium or calcium in combination with vitamin D supplementation to prevent fractures and bone loss in people aged 50 years and older: A meta-analysis. Lancet 2007 Aug 25; 370:657.