Association between dietary magnesium intake and incident chronic kidney disease: a prospective observational cohort study.

Background: Although serum magnesium deficiency is linked to higher cardiovascular disease risk, its association with chronic kidney disease (CKD) remains unclear.

Objectives: This study aimed to evaluate the relationship between dietary magnesium intake and CKD development in adults with clinically normal kidney function.

Methods: The prospective observational cohort study evaluated 188,510 participants (median age, 57.0 y; female, 54.1%) from the UK Biobank. Dietary magnesium intake was assessed through a 24-h dietary recall questionnaire compromising a list of 206 foods and 32 beverages and categorized into quintiles. The primary outcome was incident CKD diagnosed through International Classification of Diseases-10 and Office of Population Censuses and Surveys 4 codes. Incident CKD, defined as estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m, was also assessed in a subcohort with creatinine follow-up data.

Results: The median magnesium intake amount per person was 323.2 mg/d [interquartile range (IQR): 269.4-382.7 mg/d]. During 1,826,038.1 person-years of follow-up (median: 9.6 y; IQR: 9.3-10.3 y), CKD developed in 5,878 participants. The incidence of CKD was progressively higher in participants with lower magnesium intake (2.8%, 2.8%, 3.0%, 3.2%, and 3.7% in Q5-Q1, respectively). Cox regression analysis revealed that the hazard ratios (HRs) for incident CKD increased in a stepwise manner toward lower magnesium intake quintiles {adjusted HR (95% confidence interval [CI])-Q4: 0.97 (0.89, 1.06); Q3: 1.05 (0.96, 1.14); Q2: 1.12 (1.03, 1.21); Q1: 1.30 (1.20, 1.41)} relative to Q5 (P-linearity < 0.001). Similar results were observed with eGFR-defined CKD outcome [adjusted HR (95% CI)-Q4: 1.09 (0.92, 1.28); Q3: 1.15 (0.98, 1.35); Q2: 1.21 (1.03, 1.42); Q1: 1.41 (1.20, 1.65) relative to Q5; P-linearity < 0.001].

Conclusions: Lower dietary magnesium intake was associated with higher risk of incident CKD in adults with clinically normal kidney function. Further controlled studies are required to establish the potential benefit of adequate magnesium intake.