Study Shows That Calcium Supplementation Support Bone Density in Adolescent Girls
A study published in the American Journal of Clinical Nutrition presents an 18 month trial of calcium supplementation (792 mg/d) with follow-up two years after supplement withdrawal. Subjects included 96 adolescent girls with low calcium intakes. State-of-the-art measures of bone were used to determine the change in total-body, lumbar spine, and total hip bone mineral content (BMC) during supplementation and then two years after supplement withdrawal.
Over the eighteen-month period, girls who received supplemental calcium showed significantly greater gains in bone mineral content (with the exception of the hip), and bone mineral density was greater at all sites compared with the group that received a placebo. In follow-up, indicators of bone loss were still significantly lower in the supplemented group than in the control group after 18 months without the calcium supplement. However, after 24 months (or two years without supplements), the differences between groups were no longer observed.
This study indicates that calcium supplementation does indeed enhance bone mineral accumulation in teenage girls, but the effect is short-lived. The likely mechanism for the effect of the calcium is suppression of bone turnover, which is reversed upon supplement withdrawal. Therefore, calcium supplementation must be consistent and life-long to achieve full bone health benefits.
Lambert HL, Eastell R, Karnik K, Russell JM, Barker ME. Calcium supplementation and bone mineral accretion in adolescent girls: an 18-mo randomized controlled trial with 2-y follow-up. The American journal of clinical nutrition. 87(2):455-62. 2008.