Abstract P228: Relationships of Dietary and Supplement Magnesium Intake and Its Urinary Metabolomic Biomarkers With Blood Pressure: The INTERMAP Study

Abstract

Background: Magnesium (Mg) and other mineral intakes are vital contributors to a healthy diet and appear to have a modest effect on the risk of hypertension. Studies suggest that supplemental Mg can significantly lower blood pressure (BP). Here, we investigate associations of total Mg consumption with the level of its urinary metabolomic biomarkers, and BP. Method: We used cross-sectional data from the International Study of Macro-/Micronutrients and Blood Pressure (INTERMAP) on 4269 men and women aged 40-59 years from Japan, China, United Kingdom, and United States (US). Regression coefficients with BP per 2 standard deviation (SD) higher dietary Mg from food plus supplement (obtained from 24-hr dietary recalls), urinary Mg (measured by atomic absorption flame photometry) and small molecules (analysed by direct injection mass spectrometry) were estimated using multivariable models, adjusted for age, gender, population sample, intake of total energy and other confounders (see Table). To estimate overall association, country-specific regression coefficients were pooled, weighted by inverse of their variance. Results: Average Mg intakes were 454 (SD=207) mg/day for 770 persons who reported Mg supplementation (89% from US), and 300 (SD=101) mg/day for those who did not. High correlation was found between Mg intake from food plus supplements with urinary Mg ( r =0.38, P<0.0001). Partial correlations of small molecules with total Mg intake ranged from -0.007 to 0.19 for ascorbic acid (P<0.0001). Total Mg intake higher by 261.87 mg/day (2SD) was associated with a systolic BP difference of -2.65 mm Hg ( P =6x10 -5 ). Urinary Mg excretion higher by 2.66 mmol/day was associated with a diastolic BP difference of -1.02 mm Hg (P=0.02). There was a non-significant inversed association between ascorbic acid and BP in some multivariable regression models. Conclusion: Higher intake of Mg, including supplements, was associated with lower BP levels.