Researchers report (“Caffeine consumption and mortality in chronic kidney disease: a nationally representative analysis”) in Nephrology Dialysis Transplantation that consuming more caffeine may help reduce the risk of death for people with chronic kidney disease.
The possible protective effect of caffeine might be related with effects at the vascular level as caffeine is known to promote the release of substances, such as nitric oxide, that improve the function of blood vessels, according to the Portugal-based scientific team.
About 89% of the adult U.S. population consumes caffeine daily. Approximately 14% of adults in the U.S. have chronic kidney disease, which is associated with increased health care costs and a higher risk of death. The prevalence of the disease is expected to continue to increase worldwide.
“An inverse relationship between coffee consumption and mortality has been reported in the general population. However, the association between caffeine consumption and mortality in patients with chronic kidney disease (CKD) remains uncertain. We analyzed 4863 non-institutionalized U.S. adults with CKD [defined by an estimated glomerular filtration rate (eGFR) of 15–60 mL/min/1.73 m2 and/or a urinary albumin:creatinine ratio >30 mg/g] in a nationwide study using the National Health and Nutrition Examination Survey (NHANES) 1999–2010. Caffeine consumption was evaluated by 24-h dietary recalls at baseline and all-cause, cardiovascular, and cancer mortality were evaluated until 31 December 2011. We also performed an analysis of caffeine consumption according to its source (coffee, tea, and soft drinks). Quartiles of caffeine consumption were <28.2 mg/day (Q1), 28.2–103.0 (Q2), 103.01–213.5 (Q3) and >213.5 (Q4),” write the investigators.
“During a median follow-up of 60 months, 1283 participants died. Comparing with Q1 of caffeine consumption, the adjusted hazard ratio for all-cause mortality was 0.74 [95% confidence interval (CI) 0.60–0.91] for Q2, 0.74 (95% CI 0.62–0.89) for Q3 and 0.78 (95% CI 0.62–0.98) for Q4 (P = 0.02 for trend across quartiles). There were no significant interactions between caffeine consumption quartiles and CKD stages or urinary albumin:creatinine ratio categories regarding all-cause mortality. We detected an inverse association between caffeine consumption and all-cause mortality among participants with CKD.”
Comparing with people that consumed less caffeine, patients that consumed higher levels of caffeine presented a nearly 25% reduction in the risk of death over a median follow-up of 60 months.
According to Miguel Bigotte Vieira, M.D., Centro Hospitalar Lisboa Norte, one of the study's lead authors, “Our study showed a protective effect of caffeine consumption among patients with chronic kidney disease. The reduction in mortality was present even after considering other important factors such as age, gender, race, smoking, other diseases, and diet. These results suggest that advising patients with kidney disease to drink more caffeine may reduce their mortality. This would represent a simple, clinically beneficial, and inexpensive option, though this benefit should ideally be confirmed in a randomized clinical trial.”
Dr. Vieira emphasized that this observational study cannot prove that caffeine reduces the risk of death in patients with chronic kidney disease, but only suggests the possibility of such a protective effect.