One hundred forty-three boys (aged 16-18 years) were randomly assigned to receive, in double-blind fashion, 1,000 mg/day of calcium (from calcium carbonate) or placebo for 13 months. Compared with placebo, calcium supplementation significantly increased bone mineral content (BMC) of the whole body, lumbar spine, and hip. Compared with placebo, calcium supplementation also significantly increased mean height gain by 7 mm (p = 0.0004). The increase in BMC diminished after adjustment for size, suggesting that the effect of calcium on BMC was due to increased growth.

Comment: The results of this study indicate that calcium supplementation of teenage boys increases skeletal growth, resulting in greater height gain and bone mineral acquisition. This effect of calcium may be due simply to a change in the tempo of growth, or it may reflect an actual height gain that persists into adulthood. Additional studies are needed to determine whether calcium supplementation makes people end up taller.

Prentice A, et al. Calcium supplementation increases stature and bone mineral mass of 16- to 18-year-old boys. J Clin Endocrinol Metab 2005;90:3153-3161.