# Effect of EGCG Intake on Kidney Function Chronic Kidney Disease: A Nonlinear Dose–Response Relationship and Health Impact Evidence From US Adults

## TL;DR

This study finds that higher EGCG intake is linked to lower kidney function in US adults, with a nonlinear relationship for chronic kidney disease risk.

## Contribution

The study identifies a nonlinear dose-response relationship between EGCG intake and CKD risk, which is novel in kidney health research.

## Key findings

- Higher EGCG intake is associated with lower estimated glomerular filtration rate (eGFR).
- A nonlinear relationship between EGCG and chronic kidney disease (CKD) risk is observed.
- No significant association is found between EGCG and urinary albumin-to-creatinine ratio (UACR).

## Abstract

Epigallocatechin gallate (EGCG), a major catechin in tea, has been linked to various health outcomes; however, its association with kidney function remains unclear. This cross‐sectional study included 5001 participants from the 2009–2018 National Health and Nutrition Examination Survey (NHANES). Daily EGCG intake was estimated from two 24‐h dietary recalls. Kidney function outcomes included chronic kidney disease (CKD), estimated glomerular filtration rate (eGFR), and urinary albumin‐to‐creatinine ratio (UACR). Multivariable logistic and linear regression models were used to assess associations, and restricted cubic spline (RCS) models were applied to examine potential nonlinear relationships. Per 100 mg/day higher EGCG, CKD odds did not change meaningfully: crude OR 1.03 (95% CI 0.93–1.15; p = 0.59) and adjusted OR 1.09 (0.97–1.23; p = 0.14). By contrast, EGCG was inversely related to eGFR: crude β −1.01 mL/min/1.73 m2 (95% CI −1.59 to −0.43; p = 0.0006) and adjusted β −0.86 (−1.23 to −0.49; p < 0.001). UACR showed no significant associations: crude β −13.09 (95% CI −89.26 to 63.08; p = 0.736) and adjusted β −22.49 (−103.87 to 58.90; p = 0.588). RCS indicated a nonlinear association for CKD (p‐overall = 0.021; p‐nonlinear = 0.010) with an inflection near 48.750 mg/day; for eGFR, the overall association was significant (p‐overall < 0.001) with a visually N‐shaped curve and a turning point near 52.707 mg/day, though nonlinearity was not significant (p‐nonlinear = 0.063). No overall or nonlinear relationships were observed for UACR (p‐overall = 0.764; p‐nonlinear = 0.752). Higher EGCG intake was consistently associated with lower eGFR, and a significant nonlinear association with CKD risk was identified, suggesting that the relationship between EGCG and kidney function may vary across intake levels. No association was observed with UACR.

We analyzed NHANES 2009–2018 adults to relate continuous epigallocatechin gallate (EGCG) intake to chronic kidney disease (CKD), eGFR, and UACR using multivariable logistic/linear models and restricted cubic splines. EGCG was not associated with CKD in conventional models and showed no association with UACR, whereas each 100 mg/day higher EGCG was linked to a lower eGFR (adjusted β = −0.86 mL/min/1.73 m2; 95% CI –1.23 to −0.49). Spline analyses indicated a significant non‐linear association with CKD (p‐overall = 0.021; p‐nonlinear = 0.010) with an inflection near 48.750 mg/day, while eGFR's overall association remained strong without significant non‐linearity.