Tired of sodas and a fan of teas? Kombucha is for you! This naturally fizzy drink made from fermented tea is starting to take over the supermarket shelves. Being a still unknown beverage, some press sites boast of potential health benefits similar to tea. But what exactly is it?
Kombucha is traditionally prepared from black tea, sugar and a symbiotic culture of yeast and bacteria. The sugar source allows the growth of colonies of bacteria and yeast, which is characterized by a white film of cellulose on the surface of the kombucha before filtration. The type of colonies, the quantity of molecules produced by the colonies (acetic acid for acidity, for example), the type of sugar and the quantity of sugar used will have a direct impact on the beverage obtained. Bacteria and yeasts, if the production process is controlled, are not dangerous for humans. For example, baker's yeast (Saccharomyces cerevisiae) is found in Kombucha analyses, as it is in bread, beer, etc.
Back in time
Before the year 2000, a few studies were conducted on the health benefits of Kombucha. In 2000, Greenwalt et al. compiled a few studies on Kombucha used to treat certain pathologies. A previous publication by the authors of the journal showed that kombucha at low dosage (7g of tea per liter) would have an antibacterial action on common bacteria such as those that cause salmonella or other digestive disorders. A difference in action between brewed tea and kombucha was highlighted by Hesseltine et al. who found that kombucha had an antibacterial potential that tea alone did not possess. This could be related to the bacterial fermentation products found only in kombucha. Indeed, Helicobacter Pilori, a bacterium responsible for stomach diseases such as ulcers, would be eliminated by the acetic acid contained in Kombucha for 4.4g of tea brewed in 1 L. It has not yet been determined if the polyphenols in the tea play a role in the effects of kombucha or not.
Some health information about kombucha...
To date, there are several dozen publications on the effects of kombucha in vitro (cell culture) and in vivo in mice and rats. If we group the works summarized in the scientific literature, three actions of kombucha seem to be repeated in different contexts (liver metabolism, pancreas, digestion, etc.): an anti-inflammatory action in vivo, an antioxidant action in vivo and an antibacterial action in vitro. The mechanism of action of kombucha has not been precisely described, it seems that it affects a wide spectrum of enzymes and proteins of the metabolism involved in the regulation of cholesterol, blood sugar level, lipid metabolism, stimulation of antioxidant enzymes.
... Which have not been confirmed in humans
Unfortunately, there are no studies listed in the scientific literature databases that report research on kombucha in humans. Thus, the effects discovered on the cell and in animals are not confirmed in humans. Therefore, there is no evidence of kombucha's effectiveness in human pathology.
However, given the nature of the drink (presence of alcohol, acidic pH), it is important to consider possible toxicity. There have been cases of acidosis, hepatoxicity, and digestive problems (nausea, vomiting, etc.), but here again, the clinical data reported do not allow us to understand the reasons. The preparation of kombucha (sterility of the utensils, ), the acidity, the type of strains used, the acetic acid and alcohol content, all these parameters can alter the quality of the kombucha and lead to risks.
So don't believe everything that is written in the press, we will have to wait a few years before having some solid patient follow-ups to get more solid answers.
https://pubmed.ncbi.nlm.nih.gov/10914673/
https://pubmed.ncbi.nlm.nih.gov/24192111/
https://www.sciencedirect.com/science/article/pii/S1047279718307385#bib65