Abstract MP23: Urinary Magnesium Excretion and Risk of Incident Hypertension

Abstract

Background: Observational studies on dietary magnesium and risk of hypertension have reported mixed findings, but have lacked direct measures of magnesium uptake. Urinary excretion of magnesium, an indicator of dietary uptake, may clarify these discrepant findings. Methods: We examined 4,070 participants aged 28-75 years free of hypertension, kidney disease, and cardiovascular disease in the PREVEND Study, a prospective population-based cohort study. Urinary magnesium excretion was measured in two 24-hour urine collections at baseline. Incident hypertension was defined as blood pressure ≥140/90 mm Hg or initiation of antihypertensive medication. Results: During a median follow-up of 7.5 years (interquartile range: 5.5-9.2 years), 1,001 participants developed incident hypertension. Mean 24-hour urinary magnesium excretion was 4.35 ± 1.61 mmol for men and 3.65 ± 1.35 mmol for women. Urinary magnesium excretion was associated with risk of hypertension in a log-linear fashion (Figure) after adjustment for age, body mass index, sex, smoking status, alcohol intake, family history of hypertension, and urinary excretion of sodium, potassium, and calcium. Each 1-unit increment in ln-transformed urinary magnesium excretion was associated with a 26% lower risk of incident hypertension after multivariable adjustment (adjusted hazard ratio, 0.74; 95% confidence interval, 0.65-0.84). Conclusion: Urinary magnesium excretion is inversely and independently associated with risk of incident hypertension. Increasing dietary intake of magnesium could reduce the risk of hypertension. Figure legend: Natural log-transformed urinary magnesium concentrations and adjusted risk of hypertension. Magnesium levels were back-transformed to original values for ease of interpretation. Association estimated by Cox regression based on restricted splines with three knots. Dashed lines represent the 95% confidence interval. The spline curve is truncated at the 0.5 percentile and 99.5 percentile of the distribution curve.