Association of tea consumption with all-cause/cardiovascular disease mortality in the chronic kidney disease population: an assessment of participation in the national cohort.

Background: While there are numerous benefits to tea consumption, its long-term impact on patients with chronic kidney disease (CKD) remains unclear.

Method: Our analysis included 17,575 individuals with CKD from an initial 45,019 participants in the National Health and Nutrition Examination Survey (NHANES) (1999-2018). Individuals with extreme dietary habits, pregnancy, or non-CKD conditions were excluded. Key cohort demographics revealed a mean age of 62.3 years, with 52.1% female participants, and 57.3% identified as non-Hispanic White. A total of 5,835 deaths were recorded during follow-up, including 1,823 cardiovascular-related deaths. Cox and restricted cubic spline regression was used to examine the linear or nonlinear association of tea consumption with mortality. The substitution analysis explored the effects of replacing a specific type of tea with another type of tea. Subgroup analysis stratified by sex, age, body mass index (BMI), diabetes, cancer, cardiovascular disease (CVD), and urinary albumin. Sensitivity analysis was performed to ensure the reliability of our findings.

Results: After adjusting for age, sex, race, education level, marital, annual household income, energy intake, total water intake, protein intake, carbohydrate intake, dietary fiber, sugar beverages, milk whole, total monounsaturated fatty acids, total polyunsaturated fatty acids, total saturated fatty acids, smoking, metabolic equivalent of task for physical activity level (MET-PA), BMI, diabetes, hypertension, urinary albumin, estimated glomerular filtration rate (eGFR), CVD, cancer, serum sodium, serum potassium, and serum phosphorus, setting the individuals without tea consumption record as reference. Consuming up to 4 cups of tea per day was significantly associated with lower all-cause mortality compared with that never drinking tea, among CKD patients at 1-2 stages [Hazard Ratio (HR) = 0.89; 95% Confidence Interval (CI) = 0.79, 0.99; p = 0.04], while the association between tea consumption and CVD mortality didn't reach statistical significance. Dose-response effect was observed, showing that consuming up to three to five cups of tea per day was associated with mitigated risks of all-cause mortality, particularly in early CKD stages (non-linear p > 0.05). A 1 cup per day higher intake of oxidized tea was associated with a 10% lower risk of all-cause mortality in CKD stage 1-2 [HR = 0.90; 95%CI = 0.82, 0.99; p = 0.03]. Replacing 1 cup of green tea with 1 cup of oxidized tea per day was associated with an 8% and 11% lower risk of all-cause mortality [HR = 0.92; 95%CI = 0.86, 0.98; p = 0.01] and CVD mortality [HR = 0.89; 95%CI = 0.80, 1.00; p < 0.05], respectively, in individuals with CKD stages 1-2.

Conclusion: Tea consumption showed protective effects on all-cause mortality in CKD population, with potential benefits observed in terms of both the cups quantity and types of tea consumed. These findings appeared to be more prominent among early stages CKD population.