Magnesium Intake and Incident CKD

Results of recent studies have suggested an association between low levels of serum magnesium and kidney injury. However, there are few data available on whether dietary magnesium intake is related to kidney function.

Hee Byung Koh, MD, and colleagues at the Yonsei University College of Medicine, Seodaemun-gu, Seoul, Republic of Korea, conducted an observational study to examine the association between dietary intake of magnesium and incident chronic kidney disease (CKD). Results were reported during a poster session at the American Society of Nephrology Kidney Week 2022 in a poster titled Association Between Dietary Magnesium Intake and Incident CKD.

The researchers screened 210,984 European adults (40 to 70 years of age) in the UK Biobank cohort who completed dietary questionnaires from April 2009 to June 2012. Patients with underlying CKD (defined as baseline estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m² or urine to albumin-to-creatinine ratio >30 mg/g) or dietary energy intake <500 kcal or >6000 kcal were excluded.

Eligible participants were categorized into quartiles based on energy-adjusted dietary magnesium intake. The primary outcome of interest was incident CKD diagnosed using International Classification of Diseases, Tenth Edition and Office of Population Censuses and Surveys Classification of Interventions and Procedures codes. A sensitivity analysis was conducted, with the outcome of CKD defined as eGFR <60 mL/min/1.73 m².

The final analysis included 144,408 participants. Mean age was 55.8 years and 51.8% were female. The average magnesium intake per person was 352.0 mg/day. During follow-up of 1,431,716.4 person-years, 4438 patients developed incident CKD. The prevalence of CKD was progressively lower in patients with higher magnesium intake (3.5%, 3.1%, 2.9%, and 2.7% in quartiles 1-4, respectively).

In Cox regression analysis, relative to quartile 4, hazard ratios (HRs) for incident CKD decreased in a stepwise manner toward higher magnesium intake quartiles: quartile 1 HR, 0.90; 95% CI, 0.83-0.97; quartile 2 HR, 0.83; 95% CI, 0.77-0.90; quartile 3 HR, 0.80; 95% CI, 0.74-0.87 (P for trend<.001). Following adjustments for confounding factors, the association was maintained.

Results were similar with the eGFR-defined CKD outcome: quartile 1 adjusted HR (aHR), 0.93; 95% CI, 0.84-1.04; quartile 2 aHR, 0.86; 95% CI, 0.76-096; quartile 3 aHR, 0.83; 95% CI, 0.74-0.94, relative to quartile 4 (P for trend=.002).

In conclusion, the researchers said, “Higher intake of dietary magnesium may relate with lower risk of kidney function decline in adults with normal kidney function.”

Source: Koh HB, Heo GY, Kim HJ, Ko YE, Kang S-W, Park JT. Association between dietary magnesium intake and incident CKD. TH-PO873. Abstract of a poster presented at the American Society of Nephrology Kidney Week 2022; November 3, 2022; Orlando, Florida.