Magnesium acts as a cofactor for hundreds of enzymes in critical biochemical pathways, including those related to bone health
Magnesium stabilises formation of hydroxyapatite crystals, contributing to higher bone mass. Because magnesium is required as an enzymatic cofactor for the function of parathyroid hormone (PTH), magnesium deficiency impedes release of PTH and contributes to PTH resistance in target organs.
Decreased activity of PTH contributes to vitamin D deficiency, which in turn impairs calcium metabolism leading to weaker bones. Magnesium deficiency also decreases osteoblast growth, promotes oxidative stress and perpetuates inflammation — all of which contribute to decreased bone integrity.
Epidemiological and clinical studies have shown that dietary or supplemental magnesium intake increases bone mineral density, but data on the more clinically relevant outcome measure of fracture are sparse. Neither magnesium intake nor serum magnesium concentration have been definitively linked with fracture risk.
To further examine the relationship between magnesium status and fracture risk, researchers analysed prospective data on 2245 middle-aged Caucasian men in Finland.
Baseline data on serum magnesium and dietary magnesium intake were collected and participants were followed for a median of 26 years. The primary outcome measures were incident total fractures and femoral fractures.
Results showed low serum magnesium concentrations were significantly and independently associated with an increased risk of incident total and femoral fractures. The hazard ratio for total incident fracture for those in the bottom quartile was 2.10 (95% CI, 1.30-3.41), when compared with those in the top quartile of serum magnesium.
The associations remained after controlling for numerous confounders, including serum zinc and serum ionised calcium. There was no evidence of an association between dietary magnesium intake and the risk of fractures.
The authors of this study acknowledge serum magnesium may not accurately reflect body stores, but nevertheless conclude that the data suggests low serum magnesium concentrations increase the risk of future fracture.
They propose routine screening of serum magnesium concentration in patients at risk for magnesium deficiency, including those with chronic diarrhea or advancing age.