A meta-analysis of the effect of calcium intake on bone mass in young and middle aged females and males.

Evidence of a direct relationship between dietary calcium and bone mass in young adults is inconsistent. Therefore, a meta-analysis was performed to evaluate the existing literature concerning this relation in premenopausal women and adult men between the ages of 18 and 50. A computer-aided search of published papers from 1966 through 1994 was conducted. The quality of each study was assessed by examining the study design. The results of the well-designed studies wer combined to obtain quantitative conclusions. A total of 33 eligible studies were identified in the literature, representing 27 cross-sectional studies, two longitudinal and four intervention studies. The results of the cross-sectional studies in permenopausal females showed a significant correlation coefficient (r = 0.13, 95%-confidence interval = 0.09-0.16) as well as partial correlation coefficient (partial r = 0.08, 95%-confidence interval = 0.05-0.12), both weighted by sample size. The intervention studies found that calcium supplementation of approximately 1000 mg/d in premenopausal women can prevent the loss of 1% of bone/y at all bone site except in the ulna. In conclusion, the studies published to date seem to offer overall evidence that calcium intake is positively associated with bone mass in premenopausal females. This association is fairly consistent across the different study designs and is strengthened by the fact that the results are based only on studies with a high methodological quality. In males, too few studies (only three) were published to draw firm conclusions.