Coffee Consumption Promotes Better Kidney Function

Author(s):

In a new study, investigators suggest coffee may be used in prevention strategies for chronic kidney disease.

An extra cup of coffee a day could be beneficial in helping to restore kidney function.

Oliver J. Kennedy, PhD, Primary Care & Population Sciences Faculty of Medicine, University of Southampton, led a team in conducting a study determining the impact of coffee consumption on kidney function.

“This study provides evidence of a beneficial effect of coffee on kidney function,” the authors wrote. “Given widespread coffee consumption and limited interventions to prevent CKD incidence and progression, this could have significant implications for global public health in view of the increasing burden of [chronic kidney disease] CKD worldwide.”

The investigators used UK biobank baseline data for the coffee consumption genome-wide association study, examining the data of 227,666 patients.

They also used CKDGen Consortium data for kidney outcomes, which included 133,814 patients and 12,385 cases of chronic kidney disease of mostly European ancestry across numerous countries.

The outcomes of the study were estimated glomerular filtration rate (eGFR), CKD GFR categories 3-5 G3-G5; eGFR < 60 mL/min/1.73 m²), and albuminuria.

Albuminuria was defined as urinary albumin-creatinine ratio > 17 mg/g (>1.92 mg/mmol) in men and >25 mg/g (>2.83 mg/mmol) in women.

The investigators found 2126 single-nucleotide polymorphisms (SNP) linked with coffee consumption, (P <5 × 10^-8), 25 of which were independent and available in CKDGen.

“Drinking an extra cup of coffee per day conferred a protective effect against CKD G3-G5 (OR, .84; 95% CI, .72-.98; P = .03) and albuminuria (OR, .81; 95% CI, .67-.97; P = 0.02),” the author wrote. “An extra cup was also associated with higher eGFR (β = .022; P = 1.6 × 10^-6) after removal of 3 SNPs responsible for significant heterogeneity (Cochran Q P = 3.5 × 10^-15).”

The investigators used assays to measure creatinine and albumin, which varied between studies that contributed data and a sex-specific definition for albuminuria rather than KDIGO guideline recommendations.

Chronic kidney disease is currently a leading cause of morbidity and mortality worldwide, with limited strategies for prevention and treatment. The disease is currently causing substantial health care costs.

Modeling studies project a continued increase in the burden of CKD and an increase in the number of years of life lost, from around 26 million annually in 2016 to 52.5 million in 2040.

While there is no cure for chronic kidney disease, recently investigators have focused on the detection of mild/moderate chronic kidney disease and prevention of the progression to kidney failure, as well as strategies to prevent and improve management of hypertensions and diabetes in patients without chronic kidney disease.

However, there currently is a dearth of effective population-level strategies for achieving these goals.

Several epidemiologic studies report lower risks for reduced eGFR and CKD among regular coffee drinkers.

A major issue with these studies is they are at a high risk for confounding because people with chronic kidney disease risk factors, including high body mass index, hypertension, and smoking, tend to drink more coffee.

Reverse causation may also introduce bias if coffee intake decreases due to chronic kidney disease onset and progression.

The study, “Coffee Consumption and Kidney Function: A Mendelian Randomization Study,” was published online in the American Journal of Kidney Diseases.