Association between habitual coffee consumption and normal or increased estimated glomerular filtration rate in apparently healthy adults.

Habitual coffee consumption is associated with the prevention of type 2 diabetes, which often accompanies diabetic nephropathy. However, the relationship between coffee consumption and kidney function is unclear. Therefore, we investigated the associations between habitual coffee consumption and kidney function and damage assessed by the estimated glomerular filtration rate (eGFR) and proteinuria using dipstick urinalysis, respectively, in a cross-sectional study of 342 apparently healthy adults. Habitual coffee consumption was defined as drinking one or more cups of coffee per d. eGFR in coffee consumers (n 182; 80.1 (sd 15.0) ml/min per 1.73 m(2)) was significantly higher than that in non-coffee consumers (n 160; 76.9 (sd 12.6) ml/min per 1.73 m(2)) (P < 0.05). Multivariate logistic analysis showed that, compared with non-coffee consumption, coffee consumption was significantly associated with normal or increased eGFR (NIGFR) ( >or= 90 ml/min per 1.73 m(2)), but not proteinuria, which was not attenuated, even after adjustment for age, sex, smoking, tea consumption and other cardiovascular risks (OR 2.91; 95 % CI 1.51, 5.61; P = 0.001). When we took into account eGFR measured 1 year before in a subgroup of the subjects (n 262), coffee consumption (n 142) had a significant relationship with eGFR, which was consistently higher with a difference of 4.0 ml/min per 1.73 m(2) compared with non-coffee consumption (P = 0.01; two-way repeated ANOVA). Similar associations were observed in both sexes when data were reanalysed according to sex. In conclusion, our findings suggest that habitual coffee consumption is associated with NIGFR independently of clinical confounders. Further studies are needed to confirm this association and to explore whether the effect of coffee consumption on eGFR is beneficial for the kidney.