Dietary Magnesium and Kidney Function Decline: The Healthy Aging in Neighborhoods of Diversity across the Life Span Study.

BACKGROUND Prior studies suggest that certain aspects of the diet related to magnesium intake, such as dietary acid load, protein intake and dietary patterns rich in fruits and vegetables, may impact kidney disease risk. We hypothesized that lower dietary magnesium intake would be prospectively associated with more rapid kidney function decline. METHODS Among participants in the Healthy Aging in Neighborhoods of Diversity across the Life Span study with estimated glomerular filtration rate (eGFR) ≥60 ml/min/1.73 m2 at baseline (2004-2009), dietary magnesium intake was calculated from two 24-hour dietary recalls. Rapid decline was defined as ≥3% eGFR decline per year. RESULTS Median (25th-75th percentile) dietary magnesium intake was 116 (96-356) mg/1,000 kcal. Among 1,252 participants, those with lower dietary magnesium intake were younger, and were more likely to be African-American men. A total of 177 participants (14.1%) experienced rapid eGFR decline over a median follow-up of 5 years. Lower dietary magnesium intake was significantly associated with a greater odds of rapid eGFR decline (OR for tertile 1 vs. 3: 2.02, 95% CI 1.05-3.86, p value for trend across tertiles = 0.02) in analyses adjusted for sociodemographics (age, sex, race, education level, health insurance status, poverty status), kidney disease risk factors (smoking status, diabetes, hemoglobin A1c, hypertension, body mass index), baseline eGFR and dietary factors (total energy intake; diet quality; dietary intake of fiber, sodium, calcium, potassium and phosphorus). CONCLUSIONS In this urban population, lower dietary magnesium intake was independently associated with greater odds of rapid kidney function decline.