Objective: Human body is always exposed to oxidants which could be suppressed with antioxidant supplementation. Kombucha is a fermented tea beverage that has been shown to have antioxidant properties. The current systematic review and meta-analysis aimed to evaluate the antioxidant potential of kombucha tea based on the existing literature.
Materials and methods: A systematic literature search following the PRISMA 2020 guidelines was conducted to include eligible studies (original research in English language on the antioxidant activity of kombucha tea, with available full text). Data extraction was performed independently by three reviewers. Overall, the study process was undertaken from September 2024 to May 2025; final search conducted on September 112024. Random-effects meta-analysis was selected to summarize the statistical information of the antioxidative-related parameters.
Results: Fourteen studies were included in this systematic review and meta-analysis. Our results showed that kombucha had a significant effect against unfermented tea control in 2,2-diphenyl-1-picrylhydrazyl/DPPH assays (% radical scavenging ability = 9.84% (95% CI = 4.63 to 15.05%, p = 0.0002)) and half-maximal inhibitory concentration (IC50) = -64.54 mg/L (95% CI = -99.06 to -30.03 mg/L, p = 0.0002). However, other parameters such as 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)/ABTS assays, ferric reducing antioxidant power, intracellular reactive oxygen species (ROS), total phenolic compounds, and total flavonoid contents did not differ significantly between kombucha and control groups.
Conclusion: The current systematic review and meta-analysis presented a significant difference of antioxidant capacity (DPPH) of kombucha tea compared to control (unfermented tea). Nevertheless, due to high heterogeneity in the included studies, more studies should be conducted to validate kombucha tea antioxidant activity.