Abstract Body: Background: Calcium and magnesium work both together and against each other and share homeostatic regulatory systems in the kidney. Previous studies have suggested that these minerals and their intake ratio are associated with chronic health conditions such as cardiovascular disease. However, the relationship with albuminuria is not known. This study investigated the association of calcium and magnesium intake and their intake ratio with albuminuria.
Methods: This cross-sectional study analyzed data from a Japanese community-based cohort comprising 6,849 individuals aged ≥40 years (mean age 68.8 years, 51.3% women) enrolled between 2012 and 2015. Energy-adjusted dietary intake of calcium and magnesium and the calcium-to-magnesium intake ratio were derived from a validated food frequency questionnaire. The outcome was spot urinary albumin-to-creatinine ratio (ACR, mg/g). Linear and logistic regression analyses were performed with adjustments for potential confounders.
Results: Median calcium and magnesium intake values and their intake ratio were 567.9 mg/day, 326.1 mg/day, and 1.65, respectively, with a median estimated glomerular filtration rate of 73.5 mL/min/1.73 m². In the multivariable linear regression analysis, lower intakes of calcium and magnesium were associated with the log-transformed ACR but, after mutual adjustment, only calcium intake was independently associated with the ACR (β −0.084 [95% CI, −0.149, −0.019] for calcium intake and β −0.085 [95% CI, −0.204, −0.035] for magnesium intake). A lower intake ratio was associated with the log-transformed ACR (β −0.085 [95% CI, −0.150, −0.021]). In the multivariable logistic regression analysis, only the calcium-to-magnesium intake ratio demonstrated a positive association with elevated ACR (≥30 mg/g; P for trend = 0.028). These associations were evident overall and in male participants. When the participants were divided by median values of intake ratio, the association of calcium and magnesium intake with albuminuria was modified by the levels of their intake ratio, particularly in men (P for interaction: 0.017 for calcium intake and 0.008 for magnesium intake).
Conclusions: Calcium intake and the calcium-to-magnesium intake ratio might be modifiable factors for preventing albuminuria in Japanese middle-aged and older adults. Our findings supporting the importance of balancing calcium and magnesium intake might extend to cardiovascular health, especially albuminuria.