Background: Low serum magnesium (Mg) may be linked to higher cardiovascular risk through impaired glucose levels, elevated blood pressure, chronic inflammation, impaired vasomotor tone or peripheral blood flow, and electrocardiogram abnormalities. Relatively few studies have examined the association of serum Mg and coronary heart disease (CHD).
Hypothesis: Individuals with low serum Mg levels will have an increased risk for CHD.
Methods: We studied 13,349 participants (75% white, 57% women, mean age 54) free of CHD at baseline from the Atherosclerosis Risk in Communities study. Serum Mg, assessed at baseline (1987-89) and a second visit (1990-92), was averaged. Incident CHD cases through 2012 were ascertained from hospital discharge codes and death certificates and adjudicated by physician review. Multivariate Cox proportional hazards regression was used to estimate hazard ratios and 95% confidence intervals. Interactions by age, race, and sex were tested.
Results: Over a median follow-up time of 23.4 years, 1,606 incident CHD cases were identified. Low serum Mg was associated with higher CHD risk after adjustment for demographics and behaviors (Table, Model 2). Although the test for trend was significant, most of the excess risk was for the lowest Mg category. The association persisted after adjustment for potential mediators (Table, Mediation Model). There was no evidence of significant interactions between serum Mg and age, race, or sex.
Conclusion: Low serum Mg was associated with higher CHD risk, which is consistent with the proposed mechanisms and prior studies that have suggested a relationship. Interventional primary prevention studies could be considered to evaluate whether raising low serum Mg levels might lower CHD risk.