Magnesium oxide supplements and bone mass in young girls
What it found
In a year-long trial in healthy 8 to 14 year old girls, magnesium oxide supplements led to a slightly greater gain in hip bone mineral content than placebo.
The authors say the supplement was well tolerated.
What they found
Studies in people
Hip bone mineral content
Girls taking magnesium had about a 3% greater increase in overall hip bone mineral content over the year compared with the placebo group. The difference was small and the authors describe it as marginally significant.
Spine bone mineral content
The magnesium group had a slightly greater gain in spinal bone mineral content, but the difference was not statistically significant.
Bone mineral density
There was no significant difference in bone mineral density at the hip or spine between the magnesium and placebo groups, though the changes slightly favored magnesium.
Blood minerals and hormones
Levels of minerals, calcium-regulating hormones, and bone markers in the blood were similar between the two groups.
Side effects and tolerance
Only two girls reported side effects, both had loose bowel movements that went away after the dose was temporarily halved. The authors report that the supplement was well tolerated.
Compliance
About 73% of capsules were taken as counted by pill counts, and the magnesium group had higher magnesium levels in their urine, confirming they took the supplement.
What the authors conclude
“Oral Mg oxide capsules are safe and well tolerated.”
Also in their conclusions
- They conclude that oral magnesium oxide capsules are safe and well tolerated.
- They state that a positive effect of magnesium supplementation on integrated hip bone mineral content was evident in this small cohort.
- They suggest that more robust findings would have been possible with a larger study, because the trends favoring magnesium supplementation are consistent across all pubertal groups and all anatomical sites studied.
How it was done
The authors wanted to know whether magnesium supplements help young girls build more bone mass, since limited studies in adults suggest a link between magnesium intake and bone density, and no such trials had been done in children or teenagers.
They recruited 122 healthy Caucasian girls aged 8 to 14, screened their diets, and enrolled 50 with magnesium intake under 220 mg per day. The girls were randomly assigned to take either 300 mg of elemental magnesium as magnesium oxide or a placebo each day for 12 months, and 44 finished the study.
What it can’t tell you
- The study was small, so it cannot show whether the small difference in hip bone mineral content would be seen in a larger group.
- The findings only apply to Caucasian girls with magnesium intake under 220 mg per day, and cannot be extrapolated to people with higher magnesium intake, males, or other ethnic groups.
- The study lasted one year, so it cannot show whether any bone differences would affect bone health or fracture risk later in life.
Who paid
- Funding
- Funded by NICHD NIH HHS; NIDDK NIH HHS; NIA NIH HHS; PHS HHS (from the PubMed record).
- Authors work at
- Yale University School of Medicine, USA
The paper
- Title
- A randomized controlled study of effects of dietary magnesium oxide supplementation on bone mineral content in healthy girls
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Carpenter TO, DeLucia MC, Zhang JH, et al (2006). A randomized controlled study of effects of dietary magnesium oxide supplementation on bone mineral content in healthy girls. The Journal of clinical endocrinology and metabolism. doi:10.1210/jc.2006-1391Free full textPubMed 17018656DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error