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Randomized Controlled Trial
. 2006 Dec;91(12):4866-72.
doi: 10.1210/jc.2006-1391. Epub 2006 Oct 3.

A Randomized Controlled Study of Effects of Dietary Magnesium Oxide Supplementation on Bone Mineral Content in Healthy Girls

Free PMC article
Randomized Controlled Trial

A Randomized Controlled Study of Effects of Dietary Magnesium Oxide Supplementation on Bone Mineral Content in Healthy Girls

Thomas O Carpenter et al. J Clin Endocrinol Metab. .
Free PMC article


Context: The role of magnesium (Mg) as a determinant of bone mass has not been extensively explored. Limited studies suggest that dietary Mg intake and bone mineral density are correlated in adults, but no data from interventional studies in children and adolescents are available.

Objective: We sought to determine whether Mg supplementation in periadolescent girls enhances accrual of bone mass.

Design: We carried out a prospective, placebo-controlled, randomized, one-year double-blind trial of Mg supplementation.

Setting: The study was conducted in the Clinical Research Centers at Yale University School of Medicine.

Patients or other participants: Healthy 8- to 14-yr-old Caucasian girls were recruited from community pediatricians' offices. Dietary diaries from over 120 volunteers were analyzed, and those with dietary Mg intake of less than 220 mg/d were invited to participate in the intervention.

Intervention: Magnesium (300 mg elemental Mg per day in two divided doses) or placebo was given orally for 12 months.

Main outcome measure: The primary outcome measure was interval change in bone mineral content (BMC) of the total hip, femoral neck, Ward's area, and lumbar spine (L1-L4) after 12 months of Mg supplementation.

Results: Significantly increased accrual (P = 0.05) in integrated hip BMC occurred in the Mg-supplemented vs. placebo group. Trends for a positive Mg effect were evident in the pre- and early puberty and in mid-late puberty. Lumbar spinal BMC accrual was slightly (but not significantly) greater in the Mg-treated group. Compliance was excellent; 73% of capsules were ingested as inferred by pill counts. Serum mineral levels, calciotropic hormones, and bone markers were similar between groups.

Conclusions: Oral Mg oxide capsules are safe and well tolerated. A positive effect of Mg supplementation on integrated hip BMC was evident in this small cohort.


FIG. 1
FIG. 1
A, Net change in BMC during the year of the study, over all hip locations measured, expressed in grams. The least square mean of the change in BMC is represented for subjects receiving Mg by the hatched bars, and for subjects receiving placebo by the solid gray bars. Data for the entire cohort is shown in the pair of bars on the right, and by Tanner grouping in the first and second pairs. The effect of Mg treatment on overall combined hip BMC measures was greater than that of placebo in the entire cohort (P < 0.1). Subgroup analysis by maturity rating confirmed that the direction of the effect on BMC with Mg treatment was evident in both less and more mature girls. B, Net change in BMC during the year of the study by specific anatomical sites. As described above, data are presented as least square means, and subjects receiving Mg are represented by the hatched bars, and subjects receiving placebo by the dark gray bars. The difference in incremental gain in BMC at each site favored the Mg-supplemented group, although a statistically significant difference could not be shown when each site was analyzed separately. FN, Femoral neck; WT, Ward’s triangle area.

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