Low serum magnesium levels are associated with increased risk of fractures: a long-term prospective cohort study

Abstract

Magnesium, which is an essential trace element that plays a key role in several cellular processes, is a major component of bone; however, its relationship with risk of major bone fractures is uncertain. We aimed to investigate the association of baseline serum magnesium concentrations with risk of incident fractures. We analyzed data on 2245 men aged 42-61 years in the Kuopio Ischemic Heart Disease prospective cohort study, with the assessment of serum magnesium measurements and dietary intakes made at baseline. Hazard ratios [95% confidence intervals (CI)] for incident total (femoral, humeral, and forearm) and femoral fractures were assessed. During a median follow-up of 25.6 years, 123 total fractures were recorded. Serum magnesium was non-linearly associated with risk of total fractures. In age-adjusted Cox regression analysis, the hazard ratio (HR) (95% CIs) for total fractures in a comparison of the bottom quartile versus top quartile of magnesium concentrations was 2.10 (1.30-3.41), which persisted on adjustment for several established risk factors 1.99 (1.23-3.24). The association remained consistent on further adjustment for renal function, socioeconomic status, total energy intake, and several trace elements 1.80 (1.10-2.94). The corresponding adjusted HRs for femoral fractures were 2.56 (1.38-4.76), 2.43 (1.30-4.53) and 2.13 (1.13-3.99) respectively. There was no evidence of an association of dietary magnesium intake with risk of any fractures. In middle-aged Caucasian men, low serum magnesium is strongly and independently associated with an increased risk of fractures. Further research is needed to assess the potential relevance of serum magnesium in the prevention of fractures.

Keywords: Cohort study; Fracture; Magnesium; Risk factor.

Fig. 1

Hazard ratios for incident total fractures by quartiles of serum magnesium levels. a Adjusted for age; b adjusted for age, body mass index, height, systolic blood pressure, smoking status, history of diabetes, alcohol consumption, and physical activity; the mean magnesium level (mg/dl) was 1.79 for the lowest quartile; 1.93 for the second quartile; 2.03 for the third quartile; and 2.17 for the top quartile; CI confidence interval

Fig. 2

Hazard ratios for serum magnesium levels and total fractures risk by several participant level characteristics. Hazard ratios were adjusted for age, body mass index, height, systolic blood pressure, smoking status, history of diabetes, alcohol consumption, and physical activity; CI confidence interval, GFR glomerular filtration rate, HR hazard ratio; * P value for interaction; cut-offs used for age, body mass index, systolic blood pressure, physical activity, serum zinc, serum ionized calcium, serum potassium, and alcohol consumption are median values