Background: Green tea kombucha (GTK) is a fermented beverage with promising health benefits, but few studies proved its impact on human health. Thus, we aimed to investigate the impact of GTK on weight loss, inflammation, and salivary microbiota in individuals with excess body weight. Methods: This is a randomized controlled clinical trial that lasted 10 weeks with two groups of individuals with excess body weight: control (CG; n = 29; caloric restriction) and kombucha (KG; n = 30; caloric restriction + 200 mL GTK). Body composition, anthropometry, saliva, and blood collection were performed in the beginning and end of the intervention. Plasma interleukins were determined by flow cytometry. Salivary microbiota was analyzed by 16S rRNA sequencing. Results: Both groups decreased weight, BMI, and body fat (p < 0.001) after the intervention, but there were no differences between groups. The KG reduced lipid accumulation product (LAP) (p = 0.029). Both groups decreased IL-1β and IL-8, but IL-6 increased in the CG (p = 0.023) compared to the kombucha group. Alpha and beta diversity of salivary microbiota increased in the KG. Moreover, the KG presented lower Bacillota/Bacteroidota ratio (p = 0.028), and BMI was positively associated with the Bacillota phylum. Conclusions: GTK did not enhance weight loss, but it decreased the LAP. GTK helped in the inflammatory profile and induced positive changes in oral microbiota composition.

Green tea kombucha (GTK) has emerged as a promising probiotic fermented beverage. Few studies have investigated its effect on human health, mainly focusing on intestinal health, microbiota composition, and metabolomics. The present study is a pioneer in investigating the effect of GTK consumption in individuals with excess body weight. This is a randomized controlled trial, lasting ten weeks, with two groups placed under an energy-restricted diet: control (CG, n = 29), kombucha (KG, n = 30; 200 mL/d). Biological samples and questionnaires were collected before and after the intervention. Microbiota analysis used an amplification of the V4 region of 16S rRNA. Serum untargeted metabolomics used HPLC-TOF mass spectrometry. Intestinal permeability considered the urine excretion of lactulose and mannitol, plasma zonulin, and LPS-binding protein. After the intervention, no differences related to intestinal permeability and microbiota were found between groups, but only the CG had increased fecal pH, lactulose/mannitol ratio, and zonulin. In addition to this, the KG reported lower gastrointestinal symptoms related to motility compared to the CG, and discriminant metabolites (e.g., diethyl malonate) were found strictly in the KG. GTK did not significantly improve gut microbiota and intestinal permeability. However, GTK ameliorated gastrointestinal symptoms and positively influenced the serum metabolome, which may contribute to enhancing the metabolic health of individuals with excess body weight.

Green tea kombucha, produced using a green tea (Camellia sinensis) grown in Brazil, was characterized and its in vitro bioactive properties were evaluated. Overall, 92 phenolic compounds were identified (70.7% flavonoids, 25% phenolic acids, 2.2% lignans, and 1.1% other polyphenols), contributing to the observed high antioxidant capacity. The major phenolics identified were gallocatechin, catechin 5-O-gallate, and epicatechin. Green tea kombucha exhibited antibacterial activity against all tested bacteria, being more effective against Salmonella spp. In addition, green tea kombucha demonstrated antimalarial activity against both chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum, and antiproliferative activity against cancer cell lines A549, HCT8, HepG2, and HUVEC. Additionally, it presented antioxidant properties by effectively reducing the generation of reactive oxygen species (ROS) and provided protection to erythrocytes against AAPH-induced oxidative stress. Thus, green tea kombucha is abundant in antioxidants and possesses intriguing bioactive properties that can be investigated by both the food and pharmaceutical sectors.

Kombucha is a fermented beverage containing viable microorganisms during storage. Assessing the stability of refrigerated green tea kombucha is crucial to ensure quality and regulatory compliance. This study investigated green tea kombucha produced in Brazil, stored at 4°C for 120 days. Over this period, total acidity (0.197 - 0.261 g/100 mL), pH (3.41 to 3.32), acetic acid, and total phenolics remained stable, while volatile acidity increased to 37.62 mEq/L. Sucrose decreased from 22.99 to 11.57 g/L, and populations of lactic acid bacteria (7.29 to 5.63 log CFU/mL), acetic acid bacteria (7.02 to 5.09 log CFU/mL), and yeast (7.17 to 5.42 log CFU/mL) declined, attributed to high acidity, toxic compounds, oxygen limitation, and low temperature. The kombucha retained its original properties, complying with Brazilian regulations for pH, ethanol, and volatile acidity. Sensory studies are recommended to assess how these changes affect consumer perception.