Relation of Magnesium Intake With Cardiac Function and Heart Failure Hospitalizations in Black Adults: The Jackson Heart Study.

Background: Little is known about magnesium intake and risk of heart failure (HF) hospitalizations, particularly in blacks. We hypothesize that magnesium intake relates to HF hospitalization in blacks.

Methods And Results: From the Jackson Heart Study cohort (n=5301), we studied 4916 blacks recruited during 2000 to 2004 in Jackson (Mississippi), who completed an 158-item Food-Frequency Questionnaire that included dietary supplements. Daily magnesium intake derived from the questionnaire was divided by the body weight to account for body storage and stratified by quartiles (0.522-2.308, 2.309-3.147, 3.148-4.226, and ≥4.227 mg magnesium intake/kg). Cox proportional hazards modeling assessed the association between quartiles of magnesium intake/kg and hospitalizations for HF adjusting for HF risk, energy intake, and dietary factors. The cohort had a mean age=55.3 (SD=12.7 years) and composed of 63.4% women, 21.6% diabetes mellitus, 62.7% hypertension, 7.1% coronary disease, and 2.8% with known HF. When compared with participants in the first quartile of magnesium intake/kg, those with higher magnesium intake (>2.308 mg/kg) had decreased risk of HF admission, with adjusted hazard ratios of 0. 66(95% confidence interval, 0.47-0.94) in the second quartile to 0.47 (95% confidence interval, 0.27-0.82) in the highest quartile. Results were similar when individuals with previously diagnosed HF (2.8%) were excluded or when the analysis was repeated using quartiles of magnesium intake without accounting for body weight.

Conclusions: Magnesium intake <2.3 mg/kg was related to increased risk of subsequent HF hospitalizations. Future studies are needed to test whether serum magnesium levels predict risk of HF.