Background: An estimated 10 million Americans have osteoporosis. Annual health care expenditures on osteoporotic fractures exceed those of breast cancer. One inexpensive preventive measure for osteoporosis is calcium with or without vitamin D supplementation. Although earlier clinical trials have shown effectiveness of calcium in reducing fracture rates, this has not been confirmed in subsequent large trials. Tang and colleagues conducted a meta-analysis to determine the effectiveness of calcium therapy, with or without vitamin D supplementation, to prevent osteoporotic bone loss and fracture.

This Study: The authors searched multiple electronic databases to identify relevant studies. The reference lists of these studies, plus review articles and abstracts, were also examined. Studies were excluded if they had no control or placebo group, used diet or complex nutritional supplements as the calcium source, combined calcium with other anti-osteoporotic therapy, or enrolled patients with secondary osteoporosis (e.g., from steroid use). Data were abstracted from the eligible studies by two independent reviewers, and disagreements were resolved by consensus.

Results: Of the more than 7,800 references identified, 29 studies were included in the meta-analysis. There was a total of 63,897 study participants; 92 percent were women with a mean age of 67.8 years. Calcium was used alone in 16 trials. Vitamin D was combined with calcium in the remaining 13 trials.

Overall, the 17 trials using fracture as an outcome (n = 52,625) reported a consistent and highly significant 12 percent risk reduction in patients treated with calcium with or without vitamin D supplementation, and the 24 trials studying bone mineral density reported highly significant reductions in bone loss at the hip and spine. Treatment effect did not vary by sex, site of fracture, or history of fracture, but effects were higher in studies with better adherence. Risk reductions were significantly greater for patients older than 70 years compared with younger participants, and institutionalized patients benefited significantly more than those living in the community. Daily calcium doses of 1,200 mg or more and vitamin D doses of 800 IU or more were associated with significantly better results than lower doses; the addition of vitamin D did not significantly improve the treatment effect. Treatment effects were higher in patients who had low vitamin D levels and/or calcium intake before the study.

Conclusion: The authors conclude that calcium, with or without the addition of vitamin D, shows significant evidence of benefit in the prevention of osteoporotic bone loss and fracture in older patients.