Kombucha can rebalance gut ecosystem in people with obesity
Kombucha is a fermented nonalcoholic tea-based beverage produced through a symbiotic culture of bacteria and yeasts. In vitro studies have demonstrated antimicrobial, antioxidant, antiproliferative, and anti-carcinogenic properties of kombucha. However, no systematic reviews have evaluated the effects of kombucha in vivo. Thus, we aimed to evaluate the evidence that exists so far about kombucha consumption on comorbidities associated with obesity as well as on the gut microbiota. The search was conducted in accordance with PRISMA and the protocol was registered in PROSPERO (registration number: CRD42020158917). The MEDLINE/PubMed, Web of Science, LILACS, SciELO, Scopus, and Science Direct databases were used in the search considering the following terms: “kombucha” OR “kombucha tea” OR “kombucha teas” OR “tea, kombucha” OR “teas, kombucha” NOT “review.” Fifteen studies were included in this review. The results suggest that kombucha consumption attenuates oxidative stress and inflammation, improves the liver detoxification process, and reduces intestinal dysbiosis. There is evidence that kombucha consumption is beneficial for the control and treatment of obesity and associated comorbidities, as well as for the modulation of the gut microbiota in vivo.
This is according to another study- Consumption of kombucha fermented tea (KT) has always been associated with different health benefits. Many personal experiences and testimonials of KT drinkers are available throughout the world on the ability of KT to protect against a vast number of metabolic and infectious diseases, but very little scientific evidence is available that validates the beneficial effects of KT. The aim of this review is to give an overview of the recent studies in search of experimental confirmation of the numerous KT health-promoting aspects cited previously. Analysis of the literature data is carried out in correspondence to the recent concepts of health protection's requirements. Attention is given to the active compounds in KT, responsible for the particular effect, and to the mechanisms of their actions. It is shown that KT can efficiently act in health prophylaxis and recovery due to four main properties: detoxification, antioxidation, energizing potencies, and promotion of depressed immunity. The recent experimental studies on the consumption of KT suggest that it is suitable for prevention against broad-spectrum metabolic and infective disorders. This makes KT attractive as a fermented functional beverage for health prophylaxis.
This is more exclusive study done by another group of researchers-
Moreover, different yeast species can be found in kombucha, which outnumbers the acetic acid bacteria. The enzyme invertase, derived from yeasts, catalyses the hydrolysis of sucrose to glucose and fructose, producing ethanol through the glycolysis pathway. On the other hand, Gluconobacter and Acetobacter bacteria use glucose to produce gluconic acid and ethanol to produce acetic acid. The production of ethanol and acetic acid inhibits the growth of pathogenic bacteria in the kombucha.
The osmophilic yeast and bacteria that are inoculated in the beverage for fermentation are the ones responsible for the growth of what is known as tea fungus, which has the scientific name of Medusomyces gisevii. Using sucrose as a carbon source, the acetic acid bacteria of the tea produce a network of cellulose as a secondary metabolite of fermentation, mainly the bacteria Acetobacter xylinum. The symbiotic mass of bacteria and yeast adheres to the biofilm, forming a thick jelly-like membrane also called zooglea biofilm .
The
biofilm of microorganisms remains floating on the surface of the tea
with an appearance very similar to a mushroom cap, which is why it
usually receives that name . Illana mentioned that the growth of this consortium of bacteria and yeasts
induces the addition of new thicker membranes that take the shape of
their container and heightens the symbiotic effect between bacteria and
yeast . The cellulose membrane keeps the microorganisms on the
surface, allowing enough oxygen availability for its development and
protecting the microorganisms from UV rays.
Several factors play an important role in the concentration of kombucha constituents, one of them is temperature. According to the investigation by some researchers, keeping kombucha tea refrigerated at 4°C mildly decreases the content of acetic acid bacteria, from 9.3 × 106 CFU/mL to 3.4 × 106 CFU/mL during 14 days of storage; while the content of lactic acid bacteria decreases significantly, from approximately 23.5 × 106 CFU/mL to 2.7 × 103 CFU/mL during 8 days of storage. It has been reported that yeast has a positive impact on the survival of lactic acid bacteria at 30°C, but not at 12°C, which could mean that the low cooling temperature of 4°C may have limited the positive effect of yeasts over lactic acid bacteria, reducing its survival rate.
The researchers reported a sequence analysis of multiple samples of kombucha, in order to provide the most in depth study of microflora to date and to observe the changes occurred in the microbial population during kombucha production. They extracted DNA from cellulosic pellicles from 5 different geographic locations at two fermentation times. Different profiles were detected among samples, however, the major bacteria genus present was Gluconacetobacter (>85%) and a prominent Lactobacillus population was also identified (up to 30%) with a number of sub-dominant genera that have not been detected previously on kombucha. Zygosaccharomyces genus was the yeast found at >95% in the fermented tea and other greater fungal diversity not previously identified.
The team, analysed the microbiological and chemical composition of the kombucha fungus. Three samples of the tea fungus were used to evaluate its composition in different stages of fermentation, at 7, 14 and 21 days. Fibre and protein were the main components of the SCOBY. In regards to the proteins, a significantly large amount of amino acids was determined, the highest in concentration being the essential amino acids leucine and isoleucine. In addition, an increase in all the components was observed over fermentation time. Likewise, minerals like sodium, potassium, and magnesium were found.