Relations of dietary magnesium intake to biomarkers of inflammation and endothelial dysfunction in an ethnically diverse cohort of postmenopausal women.

OBJECTIVE: Although magnesium may favorably affect metabolic outcomes, few studies have investigated the role of magnesium intake in systemic inflammation and endothelial dysfunction in humans. RESEARCH DESIGN AND METHODS: Among 3,713 postmenopausal women aged 50-79 years in the Women's Health Initiative Observational Study and free of cardiovascular disease, cancer, and diabetes at baseline, we measured plasma concentrations of high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), turnor necrosis factor-alpha receptor 2 (TNF-alpha-R2), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), and E-selectin. Magnesium intake was assessed using a semiquantitative food frequency questionnaire. RESULTS: After adjustment for age, ethnicity, clinical center, time of blood draw, smoking, alcohol, physical activity, energy intake, BMI, and diabetes status, magnesium intake was inversely associated with hs-CRP (P for linear trend = 0.003), IL-6 (P < 0.0001), TNF-alpha-R2 (P = 0.0006), and sVCAM-1 (P = 0.06). Similar findings remained after further adjustment for dietary fiber, fruit, vegetables, folate, and saturated and trans fat intake. Multivariable-adjusted geometric means across increasing quintiles of magnesium intake were 3.08, 2.63, 2.31, 2.53, and 2.16 mg/l for hs-CRP (P = 0.005); 2.91, 2.63, 2.45, 2.27, and 2.26 pg/ml for IL-6 (P = 0.0005); and 707, 681, 673, 671, and 656 ng/ml for sVCAM-1 (P = 0.04). An increase of 100 mg/day magnesium was inversely associated with hs-CRP (-0.23 mg/l +/- 0.07; P = 0.002), IL-6 (-0.14 +/- 0.05 pg/ml; P = 0.004), TNF-alpha-R2 (-0.04 +/- 0.02 pg/ml; P = 0.06), and sVCAM-1 (-0.04 +/- 0.02 ng/ml; P = 0.07). No significant ethnic differences were observed. CONCLUSIONS: High magnesium intake is associated with lower concentrations of certain markers of systemic inflammation and endothelial dysfunction in postmenopausal women.