After six months of lab work, I am glad to finally share the results of my research with you! During my internship I investigated the probiotic potential of the authentically brewed kombucha at YAYA Kombucha. Because of these authentic brewing methods, the microorganisms that ferment the tea into this funky tasting kombucha are still alive in the bottle. It is speculated that these living bugs would be beneficial for your gut health. However, the scientific research into this topic is scarce. Because of this, I decided to go and explore this topic in more detail by testing the gastrointestinal survival of the living bacteria in the kombucha. If these bacteria would survive your gastric acid, enzymes, and bile along the way, it could indicate a possible positive effect on your gut health. I have previously explained how this works here.
Firstly, I analysed the microbiological composition of kombucha to get a clearer picture of which bacteria and yeast are present in the drink. It was found that the kombucha produced by YAYA Kombucha consisted mostly of acetic acid bacteria, which are often found in the production of vinegar. They are, however, also typical for kombucha. During the first days of the fermentation process, these bacteria convert the sugar present in the tea into acetic acid, flavours, and aromas under the presence of oxygen. Remarkably, the lactic acid bacteria Oenococcus oeni was detected in the kombucha. This bacteria plays a major role in the process of wine fermentation, where it breaks down acids to make the wine less tart. Moreover, the dominant species of yeast in the drink belonged to the Dekkera (Brettanomyces) Bruxellensis which is also known for its important role during fermentation in the wild-fermented Belgium Lambic beers. This yeast creates the typical so-called ‘horse’ aroma which distinguishes the premium Lambic beers from average ones.
Having a clear image of the microbiological composition, I wanted to know more about their abilities to survive digestion. To test this, a lab model of the gastrointestinal tract was used called TIM-1 (TNO in vitro model of the gastrointestinal tract), which simulates the stomach and the small intestine. Having a lab model of the digestion allows for analysis of the bacterial survival rate during digestion. The results indicated that the selected bacteria were able to survive the upper part of the digestion. When comparing this to bacterial isolates, the kombucha culture had an improved survival rate. This means that the symbiotic culture of bacteria and yeast team-up to support each other in their survival through digestion. These survival rates ranged from 25 to 75%, depending on the type of bacteria, of the total ingested bacteria in the kombucha. This is a lot when compared to the survival rate of bacteria in your yoghurt (0,01%).
This research was the first study where analysis was done of the gastrointestinal survival of the bacteria in kombucha. With the knowledge and insights gathered during this research, we already have unravelled a bit more of the probiotic potential of this interesting beverage. Nevertheless, many more studies will be needed to determine how these bacteria affect the gut microbiota and whether they actually contribute to health. I hope that this study will motivate other students and/or experts to unravel the mysteries behind this fascinating living beverage, thereby making kombucha even more outstanding!