Kombucha: Boosting Immunity or Just Toxic Tea?
Said to boost the immune system and reverse the aging process, the concoction known as kombucha is also called kombucha tea and kombucha mushroom tea.
However, kombucha technically is not a member of the mushroom family; rather, it is a live culture of multiple species of yeast and bacteria, grown to make a mildly acidic fermented beverage.1,2 A sac resembling a mushroom in size and color forms on top of the tea after it ferments.1
Ancient writings document the origin of kombucha in eastern Asia during the Chinese Tsin dynasty in 212 B.C.2 The use of kombucha spread gradually across Russian and Western Europe over the next several hundred years, and it began to gain popularity in the early 20th century.2
In the United States, annual sales of kombucha and similar products reached $295 million by 2010—a 25% increase from just 2 years earlier—which equates to more than 1 million servings of this "functional beverage."3
Kombucha is made by fermenting yeast, sugar, and black or green tea. The resulting product is referred to in microbiological terms as a SCOBY, or, a symbiotic colony of bacteria and yeast. As the fermentation progresses, a slimy mat-like growth called a pellicle forms on the surface—the so-called "mushroom."
The liquid in the lower part of the container is the tea that is consumed.4 Proponents of the tea claim that it has immune-enhancing, antibacterial and anti-inflammatory benefits. Kombucha is described as effervescent, with a slightly alcoholic, ginger-like flavor.
As a result of both the original ingredients and the fermentation process, the main chemical components of kombucha are acetic acid and a rich concentration of B vitamins, as well as many enzymes, antioxidants, and amino acids.4
Most data indicate that the modest antimicrobial action of kombucha is due largely to the low pH caused by the acetic acid component of the tea. Similar actions were seen, however, in studies exploring the in vitro antibacterial action of kombucha that had been neutralized to a pH of 7.5
Researchers theorize that those actions may be indicative of more complex mechanisms of action related to the enzymes and complex proteins found in the tea.5 Laboratory testing showed impressive zones of inhibition in plate cultures of kombucha inoculated with various Staphylococcus, Listeria, and Micrococcus species.4
One genus of yeast found in kombucha, Gluconacetobacter, is responsible for catalyzing the production of glucuronic acid in the tea.6 Glucuronic acid is known to be a potent cellular protectant, cytoplasmic membrane stabilizer, and mitochondrial enhancer.
An area of specific interest for kombucha researchers is the possible role glucoronic acid plays in hepatoprotection and detoxification.7