Effects of green tea supplementation on antioxidant status and inflammatory markers in adults: a grade-assessed systematic review and dose-response meta-analysis of randomised controlled trials.

2025
Journal of nutritional science 14
- Mohammad Jafar Dehzad
- Hamid Ghalandari
- Mehran Nouri
- Maede Makhtoomi
- Moein Askarpour

PubMed: 40160899
DOI: 10.1017/jns.2025.13

Study Design

Type: Meta-Analysis
Methods: Systematic review and meta-analysis of randomised controlled trials (RCTs); searched online databases (PubMed, Scopus, Web of Science Core Collection, and Google Scholar) for articles published from inception up to February 2024; 38 RCTs included

Green tea, a plant rich in bioactive compounds, has been highlighted for its beneficial effects. In the present systematic review and meta-analysis of randomised controlled trials (RCTs), the impact of green tea on inflammatory and oxidative markers is investigated. Using pre-defined keywords, online databases (PubMed, Scopus, Web of Science Core Collection, and Google Scholar) were searched for relevant articles, published from inception up to February 2024. The outcomes included C-reactive protein (CRP), tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1 beta (IL-1β), total antioxidant capacity (TAC), malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GPX). Analyses of subgroups, linear, and non-linear associations were also carried out. Out of 1264 records initially retrieved, 38 RCTs were included. Supplementation with green tea improved the following indicators: IL-1β (weighted mean difference (WMD): -0.10 pg/mL; 95% CI: -0.15, -0.06), MDA (WMD: -0.40 mcmol/L; 95 % CI: -0.63, -0.18), TAC (WMD: 0.09 mmol/L; 95% CI: 0.05, 0.13), SOD (WMD: 17.21 u/L; 95% CI: 3.24, 31.19), and GPX (WMD: 3.90 u/L; 95% CI: 1.85, 5.95); but failed to improve others, including CRP (WMD: 0.01 mg/L; 95% CI: -0.14, 0.15), IL-6 (WMD: -0.34 pg/mL; 95% CI:-0.94, 0.26), and TNF-α (WMD: -0.07 pg/mL; 95% CI: -0.42, 0.28). Supplementation with green tea can improve the body's oxidative status. However, the results showed no significant effect of green tea on inflammatory markers, except for IL-1β. Further studies are needed to determine the effectiveness of green tea, particularly on inflammatory status.

Research Insights

green tea→Improved Antioxidant Capacity
Supplementation with green tea improved the following indicators: ... TAC (WMD: 0.09 mmol/L; 95% CI: 0.05, 0.13)
Effect
Beneficial
Effect size
Small
Dose
not specified across all RCTs
green tea→Improved Glutathione Peroxidase Level
Supplementation with green tea improved the following indicators: ... GPX (WMD: 3.90 u/L; 95% CI: 1.85, 5.95)
Effect
Beneficial
Effect size
Small
Dose
not specified across all RCTs
green tea→Improved Superoxide Dismutase Level
Supplementation with green tea improved the following indicators: ... SOD (WMD: 17.21 u/L; 95% CI: 3.24, 31.19)
Effect
Beneficial
Effect size
Small
Dose
not specified across all RCTs
green tea→Reduced C-Reactive Protein Levels
but failed to improve others, including CRP (WMD: 0.01 mg/L; 95% CI: -0.14, 0.15)
Effect
Neutral
Effect size
Small
Dose
not specified across all RCTs
green tea→Reduced Interleukin-1 Beta Level
Supplementation with green tea improved the following indicators: IL-1β (weighted mean difference (WMD): -0.10 pg/mL; 95% CI: -0.15, -0.06)
Effect
Beneficial
Effect size
Small
Dose
not specified across all RCTs
green tea→Reduced Interleukin-6 Levels
but failed to improve others, including ... IL-6 (WMD: -0.34 pg/mL; 95% CI:-0.94, 0.26)
Effect
Neutral
Effect size
Small
Dose
not specified across all RCTs
green tea→Reduced Malondialdehyde
Supplementation with green tea improved the following indicators: ... MDA (WMD: -0.40 mcmol/L; 95 % CI: -0.63, -0.18)
Effect
Beneficial
Effect size
Small
Dose
not specified across all RCTs
green tea→Reduced Tumor Necrosis Factor Alpha
but failed to improve others, including ... TNF-α (WMD: -0.07 pg/mL; 95% CI: -0.42, 0.28)
Effect
Neutral
Effect size
Small
Dose
not specified across all RCTs