Coffee and tea consumption in relation to estimated glomerular filtration rate: results from the population-based longitudinal Doetinchem Cohort Study

Background: Although coffee consumption and tea consumption have been linked to diabetes, the relation with kidney function is less clear and is underresearched. Objective: We investigated the prospective associations of coffee and tea consumption with estimated glomerular filtration rate (eGFR). Design: We included 4722 participants aged 26-65 y from the Doetinchem Cohort Study who were examined every 5 y for 15 y. Coffee and tea consumption (in cups/d) were assessed at each round. eGFR was assessed by using the Chronic Kidney Disease Epidemiology Collaboration equation based on both plasma creatinine and cystatin C. We determined the association between categories of coffee and tea intake and 1) eGFR and 2) subsequent annual changes in eGFR by using generalized estimating equation analyses. Results: Baseline mean +/- SD eGFR was 108.0 +/- 14.7 mL . min(-1) 1.73 m(-2). Tea consumption was not associated with eGFR. Those individuals who drank >6 cups coffee/d had a 1.33 (95% CI: 0.24, 2.43) mL . min(-1) . 1.73 m(-2) higher eGFR than those who drank <1 cup/d (P-trend = 0.02). This association was most apparent among those with a median age of y at baseline, with eGFR being 2.47 (95% CI: 0.42, 4.51) mL . min(-1) . 1.73 m(-2) higher in participants drinking >6 cups/d compared with <1 cup/d (P-trend = 0.02). Adjustment for biological risk factors and coffee constituents did not attenuate the associations. Neither coffee nor tea consumption was associated with changes in eGFR. Conclusions: Coffee consumption was associated with a slightly higher eGFR, particularly in those aged >= 46 y. The absence of an association with eGFR changes suggests that the higher eGFR among coffee consumers is unlikely to be a result of glomerular hyperfiltration. Therefore, low to moderate coffee consumption is not expected to be a concern for kidney health in the general population.