University of Michigan
Department of Pediatrics
Evidence-Based Pediatrics Web Site

Question

• In adolescent females with inadequate dietary calcium consumption, does calcium supplementation result in significantly increased accumulation of bone mineral density over a period of 1-2 years?

Clinical Bottom Lines

1. Subjects who received supplementation to increase their total calcium intake to ~110% of the minimum RDA of calcium showed increases in lumbar spine and total body bone density that were significantly greater (P< or = 0.05) than those in the control group, who had an average calcium intake of 80% of the RDA.¹
2. Unfortunately, this study did not control for exercise level, which is known to be a determinant of bone mineral density, and therefore its results should be interpreted with caution.
3. It is also, of course, unclear how long any benefits from this length of treatment in terms of bone density would be retained.

Summary of Key Evidence

1. The study subjects were derived from four high schools local to the area of the study. 112 female subjects aged 11.9 +/- 0.5 years were selected for participation in the study. Patients included in the study were premenarchal, caucasian, between 80-120% of ideal body weight for height, had no known eating disorders, took no medication regularly, and had no medical disorders known to affect bone development.¹
2. Subjects were assigned by stratified randomization, which balanced the groups with respect to BMI and lumbosacral bone mineral density (LSBMD), to receive daily supplementation of either 500 mg Calcium Citrate Malate supplementation or placebo.
3. At the beginning of the study and q 6 months through the 18-month study, x-ray absorptiometry was used to measure total body bone mineral density and content as well as lumbar spine bone mineral density and content. The two groups were, as above, balanced with respect to LSBMD at baseline.
4. The treatment group's total calcium intake (~110% of the minimum RDA) was significantly greater than that of the control group (~ 80 % of the minimum RDA).
5. Over the course of the study, the supplemented group, when compared with the placebo group, had significantly greater increases in lumbar spine bone mineral density and content (18.7% versus 15.8%, P value =0.03), and also in total body bone mineral density (39.4% versus 34.7%, P value = 0.05).
6. Adverse effects of the supplementation are not mentioned in the study, although of the 18 original subjects who were randomized but did not complete the study; the reason for this was aversion to taking a daily pill.
7. The study appears to be valid, although it is not clear whether the outcome assessors were blinded.

Additional Comments

• The study did not control for exercise status, a known contributor to accumulation of bone mineral density in adolescent girls.
  

Citation

1. Lloyd T, Andon MB, Rollings N, et al. Calcium Supplementation and Bone Mineral Density in Adolescent Girls. JAMA 1993;270:841-4.

CAT Author: Tabitha Rubash, MD

CAT Appraisers: Kenneth Pituch, MD

Date appraised: March 16, 2005