Effect of green tea supplementation on antioxidant status in adults: A systematic review and meta-analysis of randomized clinical trials

Niloufar Rasaei, Omid Asbaghi, Mahsa Samadi, Leila Setayesh, Reza Bagheri, Fatemeh Gholami, Neda Soveid, Krista Casazza, Alexei Wong, Katsuhiko Suzuki*, Khadijeh Mirzaei*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

13 Citations (Scopus)


It is well-established that green tea supplementation has antioxidant properties. However, whether green tea supplementation leads to oxidative stress reduction remains unclear, as clinical investigations on this subject have yielded inconsistent outcomes. Consequently, we aimed to determine the effects of green tea supplementation on oxidative stress in adults. A systematic search of English language publications up to 21 August 2021 was carried out in PubMed, Scopus, Embase, and ISI Web of Science, utilizing pertinent keywords. These searches included randomized controlled trials (RCTs) evaluating the relationship between green tea supplementation, malondialdehyde (MDA), and total antioxidant capacity (TAC) in adults. A random-effects model was used to estimate the weighted mean difference (WMD) and 95% confidence intervals (95% CI). Meta-regression and non-linear dose-response analyses were performed to investigate the association between the dosage of green tea (mg/day) and the duration of the intervention (weeks) with pooled effect size. Sixteen RCTs with seventeen arms including 760 participants met the inclusion criteria. Our results indicated that green tea supplementation had significant effects on TAC (weighted mean difference [WMD]: 0.20 mmol/L; 95% CI: 0.09, 0.30, p < 0.001) and significant heterogeneity between studies (I2 = 98.6%, p < 0.001), which was largely related to gender and body mass index (BMI). Subgroup analysis in TAC identified a significant relationship except with low dose supplementation and obese individuals. No relationship between MDA and green tea supplementation was observed in any subgroups; however, meta-regression analysis revealed a linear inverse association between the dosage and significant change in MDA (r = −2117.18, p = 0.017). Our outcomes suggest that green tea supplementation improves TAC and affects MDA based on the dose of the intervention in adults. Future RCTs with longer durations are needed to expand our findings.

Original languageEnglish
Article number1731
Issue number11
Publication statusPublished - 2021 Nov


  • Green tea
  • Malondialdehyde
  • Oxidative stress
  • Total antioxidant capacity

ASJC Scopus subject areas

  • Food Science
  • Molecular Biology
  • Physiology
  • Biochemistry
  • Clinical Biochemistry
  • Cell Biology


Dive into the research topics of 'Effect of green tea supplementation on antioxidant status in adults: A systematic review and meta-analysis of randomized clinical trials'. Together they form a unique fingerprint.

Cite this