Does drinking coffee affect kidney function? The latest medical research indicates that...

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Coffee is a daily drink in Europe and the United States. With the development of globalization, coffee is becoming more and more common in China. But studies have found that coffee is associated with an increased risk of dementia, insulin resistance, type 2 diabetes, liver cirrhosis and osteoporosis, as well as increased frequency and volume of urination. However, the effect of coffee on kidney function is not clear.

Recently, Karn Wijarnpreecha and colleagues at Bassett Medical and Health Center conducted a meta-analysis to assess the correlation between coffee and CKD. The results were published in the journal International Journal of Clinical Practice.

Research review

The researchers screened 2438 articles published in the MEDLINE and EMBASE databases before June 2016 and eventually included 4 studies with 14898 patients. Inclusion criteria: (1) case-control, cross-sectional or cohort studies comparing the risk of CKD between coffee drinkers and non-coffee drinkers; (2) the study data included standardized incidence ratios (SIR) of odds ratio (OR), relative risk (RR), risk ratio (HR) or 95% confidence interval (CI). Inverse variance analysis and random effect analysis were used to analyze the data.

Main results

There was no significant correlation between coffee and CKD, and the total RR was 0.71 (95%CI:0.47-1.08) (figure 1). The statistical heterogeneity is moderate: I2 is 66%. Subgroup analysis (female and male subgroups) showed that there was no significant correlation between coffee and CKD risk in male subgroups. The total RR of female subgroup was 0.81 (95%CI:0.58-1.13), and that of male was 1.10 (95%CI:0.94-1.29) (see figures 2 and 3).

Figure 1 Coffee and CKD risk

Fig. 2 correlation between coffee and CKD risk

Fig. 3 correlation between male coffee and CKD risk

This study is the first meta-analysis to assess the risk of coffee and CKD, and the results show that there is no significant correlation between CKD and coffee. Some researchers believe that coffee can protect renal function and reduce the risk of renal injury, but the specific mechanism is not clear. The possible mechanisms are: coffee contains a variety of ingredients, which can protect glomerular endothelial cells from oxidative stress; coffee can reduce hyperuricemia and delay the progress of CKD; the anti-diabetic effect of coffee helps to prevent the progression of diabetic nephropathy.

Subgroup analysis showed that there was no significant correlation between coffee consumption and CKD in men, which may be due to the limited research data; coffee consumption in women can reduce the risk of CKD, but further research is needed to confirm the potential correlation between coffee and the risk of CKD progression in women.

Translated from Association of coffee consumption and chronic kidney disease: a meta-analysis. Volume 71, Issue 1. January 2017. E12919