Impact of dairy products and dietary calcium on bone-mineral content in children: Results of a meta-analysis

Objective Although calcium is essential for maintaining bone health in children, the optimum dietary intake of calcium in this age group, particularly in the form of dairy foods, is not well defined. A meta-analysis was conducted to examine the impact of dietary calcium/dairy supplementation on bone mineral content in this age group. Methods Data were pooled from randomized controlled intervention trials and observational studies using previously described methods. The outcome of interest was a summary mean difference bone mineral content. Sensitivity analyses were employed to evaluate any observed statistical heterogeneity and to examine the influence of specific study characteristics on the summary estimate of effect. Results Initially combining data from twenty-one randomized controlled trials (RCTs) using total body bone mineral content (TB-BMC) as the outcome of interest, yielded a non-statistically significant increase in TB-BMC of 2 g (supplemented versus controls). These data demonstrated substantial statistical heterogeneity with sensitivity analyses revealing that among study subjects with normal or near normal baseline dietary calcium/dairy intakes, supplemental dairy/calcium showed little impact on bone mineral content. Sensitivity analyses suggested that baseline calcium intake could potentially account for the statistical heterogeneity. Pooling the three reports utilizing low intake subjects yielded a statistically significant summary mean BMC of 49 g (24.0–76–6). Pooling two RCTs using calcium/dairy supplement plus vitamin D was also associated with an increase in lumbar spine BMC of, on average, 35 g (− 6.8–41.8). The lack of data using BMC measurements at other anatomic sites as well as sparse data from non-randomized studies, precluded further statistical pooling. Conclusion Increased dietary calcium/dairy products, with and without vitamin D, significantly increases total body and lumbar spine BMC in children with low base-line intakes.