Fermentation time Determines Anti-inflammatory and Osteoprotective Activity of Green Tea Kombucha in a Rat Model of Experimental Periodontitis

This study aimed to characterize the microbial composition of green tea-fermented kombucha at different fermentation times and to evaluate its effects on inflammation and alveolar bone loss in rats with periodontitis. Microbial diversity was first assessed by metagenomic sequencing targeting bacterial 16 S rRNA and fungal 18 S rRNA regions. Sixty male rats were divided into six groups: control, periodontitis without treatment, green tea treatment, and kombucha fermented for 4, 8, or 12 days. Kombucha or green tea was administered daily by oral gavage for 39 days. Periodontitis was induced by ligation of the maxillary second molar on day 28. After euthanasia, hemimaxillae, liver, kidney, and blood samples were collected for analysis. Kombucha fermented for 4 days showed the highest abundance of bacteria from the Acetobacteraceae family and yeasts from the Saccharomycetaceae family. This fermentation time also produced the most pronounced reduction in periodontal inflammation and alveolar bone loss, with lower expression of tumor necrosis factor-alpha (42,9%) and receptor activator of nuclear factor kappa-B (43,6%), as well as higher expression of osteoprotegerin (approximately 55,4%) in periodontal tissues compared to animals with periodontitis without treatment. Notably, kombucha did not induce renal or hepatic toxicity regardless of fermentation time. These findings suggest that kombucha, particularly after 4 days of fermentation, reduces inflammation and alveolar bone loss without systemic toxicity, supporting its potential as an adjunctive therapy for periodontitis.