The kombucha craze has hit the mainstream and beyond. Every grocery store I shop has a kombucha section in the produce aisle, with many different brands. I walked into my local Vitamin Shoppe the other day and saw that they had added an organic kombucha tap. The store even had giant glass jugs for purchase to store it in the refrigerator, when you need that fermented beverage shot to get you through the day. Now, grandmothers and athletes can get the beverage straight from the tap for their digestive ailments. I have shared my research and mix recommendations about yogurt and kefir, but where does kombucha stand in improving or causing digestive health issues?

What is Kombucha?

Kombucha is a yeast-fermented beverage (it also does contain some bacteria) produced from tea. Kombucha is effervescent, generally sweetened (to make the taste more palatable), and includes differing amounts of alcohol. Kombucha probably originated in Asia around 220 B.C. and eventually was brought to Europe through trade routes. Kombucha was very popular in Germany and Switzerland in the 20th century.

“It was first used in East Asia for its healing benefits. Kombucha originated in northeast China (Manchuria) where it was prized during the Tsin Dynasty (“Ling Chi”), about 220 B.C., for its detoxifying and energizing properties. In 414 A.D., the physician Kombu brought the tea fungus to Japan, and he used it to cure the digestive problems of the Emperor Inkyo. As trade routes expanded, kombucha (former trade name “Mo-Gu”) found its way first into Russian (as Cainiigrib, Cainii kvass, Japonskigrib, Kambucha, Jsakvasska) and then into other eastern European areas, appearing in Germany (as Heldenpilz, Kombuchaschwamm) around the turn of the 20th century. During World War II, this beverage was again introduced into Germany, and in the 1950’s it arrived in France and also in France-dominated North Africa where its consumption became quite popular. The habit of drinking fermented tea became acceptable throughout Europe until World War II which brought widespread shortages of the necessary tea leaves and sugar. In the postwar years, Italian society’s passion for the beverage (called “Funkochinese”) peaked in the 1950s. In the 1960s, science researchers in Switzerland reported that drinking kombucha was similarly beneficial as eating yogurt and kombucha’s popularity increased. Today, kombucha is sold worldwide in retail food stores in different flavors, and kombucha culture is sold in several online shopping websites.” ¹

Kombucha was later marketed in the United States in the 1990’s for proper digestion and to improve one’s health. Kombucha tea is prepared by placing the culture (also known as SCOBY, symbiotic colony of bacteria and yeast) into a mixture of cooled brewed tea and sweetener. The culture ferments the polyphenols in the tea and the sweetener, producing carbonation and alcohol. The fermented drink is then placed in the refrigerator to slow down carbonation, fermentation, and alcohol production so that the kombucha can be safely consumed later. If you have ever ingested shorter fermented kombucha it has a kind of fruity sour taste to it. The longer it is fermented, the more the flavor becomes vinegary because of the more significant quantity of lactic and acetic acid. The fermented beverage contains many different amounts of acids, polyphenols, ethanol, vitamins, and minerals depending on fermentation length and substances used. Jerusalem artichoke tubers that are fermented with a SCOBY, for example, contain the prebiotic inulin and ascorbates. The main fermented contents that are used are black tea, green tea, Jerusalem artichoke tubers, and animal milk. ^{2 3}

“Chemical analysis of kombucha showed the presence of various organic acids, such as acetic, gluconic, glucuronic, citric, L-lactic, malic, tartaric, malonic, oxalic, succinic, pyruvic, usnic; also sugars, such as sucrose, glucose, and fructose; the vitamins B1, B2, B6, B12, and C; 14 amino acids, biogenic amines, purines, pigments, lipids, proteins, some hydrolytic enzymes, ethanol, antibiotically active matter, carbon dioxide, phenol, as well as some tea polyphenols, minerals (manganese, iron, copper, zinc, cobalt, chromium, sulfur), anions (iodide, chloride, bromide, fluoride), heavy metals (nickel, lead), D-saccharic acid-1,4-lactone, as well as insufficiently known products of yeast and bacterial metabolites.” ⁴

Is Kombucha Right for you?

Kombucha is reaching a new level of popularity, but is it right for you? Many people consume the fermented drink as a probiotic drink. Many people that I have coached, however, are not able to tolerate it. There are some pros associated with the use of the beverage to improve your health, but I believe there are more negatives associated with its use.

Pros

• Kombucha contains many different probiotic bacteria and yeast. Probiotic bacteria include Acetobacter, a genus of bacteria that produce the short chain fatty acid acetate, Lactobacillus, and Komagataeibacter, which produces D-saccharic acid-1,4-lactone that inhibits beta-glucuronidase. Probiotic yeast include Saccharomyces and Candida species. ^{5 6}
• Kombucha tea contains acids that have antimicrobial effects like acetate and butyrate. “Kombucha tea containing 33 g/L total acid (7 g/L acetic acid) had antimicrobial efficacy against Agrobacterium tumefaciens, Bacillus cereus, Salmonella choleraesuis serotype Typhimurium, Staphylococcus aureus, and Escherichia coli, but not for Candida albicans. Kombucha tea could inhibit the growth of the pathogens Entamoeba cloacae, Pseudomonas aeruginosa, B. cereus, E. coli, Aeromonas hydrophila, Salmonella typhimurium, Salmonella enteritidis, Shigella sonnei, Staphylococcus epidermis, Leuconostoc monocytogenes, Yersinia enterocolitica, S. aureus, Campylobacter jejuni, Helicobacter pylori, and C. Albicans. Antimicrobial activity of kombucha tea is largely attributable to the presence of organic acids, particularly acetic acid, large proteins, and catechins (EGCG). Acetic acid and catechins are known to inhibit some Gram-positive and Gram-negative microorganisms.” D-saccharic acid-1,4-lactone inhibits dysbiotic bacteria produced increased beta-glucuronidase which deconjugates bilirubin leading to the formation of calcium billrubinate. Increased calcium bullrubinate causes biliary sludge, gallstones, and lipid digestive issues. ^{7 8 9}
• Kombucha supplies acids including malic, butyric, acetic, L-lactate, citrate, succinate, pyruvic, and glucuronic acid to improve your health. Kombucha is high in both acetic, L-lactate, and glucuronic acid. ^{10 11}
• Kombucha contains some glucuronic acid (sadly, kombucha does not contain much glucuronic acid) which binds to many different toxic molecules and byproducts and increases their excretion from the body through a process known as glucuronidation. Butyric acid combined with glucuronic acid can help reduce leaky gut and parasitical infections. “Butyric acid produced by the microbial consortium in the fermentation process is known to protect human cellular membranes. In combination with glucuronic acid, this complex has the ability to strengthen the walls of gut and give protection against parasites.” ^{12 13 14}
• Kombucha contains differing amounts of the minerals, manganese, iron, copper, zinc, cobalt, chromium, iodine, and sulfur. ¹⁵
• Kombucha contains differing amounts of vitamins B1, B2, B6, B12, and C. Kombucha is an excellent source of vitamin B12 for vegans. ¹⁶
• Kombucha made from tea contains polyphenols including EC (epicatechin), ECG (epicatechin gallate), EGC (epigallocatechin), theaflavin (TF), and EGCG (epigallocatechin gallate). ¹⁷
• Kombucha maybe hepatoprotective because of D-saccharic acid-1,4-lactone, which is a product of the glucuronate detoxification pathway. Glucuronidation metabolizes many medications including Tylenol, toxins (polycyclic aromatic hydrocarbons, some nitrosamines, aromatic amines and fungal toxins), and steroid hormones. ^{18 19 20}
• Kombucha might be better tolerated in people with Th1 dominance, because of minor glutathione depletion from alcohol, tea polyphenols like EGCG reducing Th1, and probiotic yeast increasing Th2. ^{21 22}

Cons

• Kombucha may cause issues in people with histamine intolerance, mast cell activation disorder, Th1/Th2/Th17 dominance, alcohol flush syndrome, auto-brewery syndrome, and yeast sensitivity. Kombucha is fermented, therefore it should contain histamine, it may contain differing amounts of alcohol, and it does contain yeast which increases expression of mast cells in the gut in people with Th2 and Th17 dominance. Though kombucha might help some people with Th1 dominance, kombucha does increase Il-17, which in some people might increase Th1, inflammation, and cause or worsen colitis. Kombucha does contain a good amount of yeast, specifically Candida and Saccharomyces cerevisiae, so people with auto-brewery syndrome (Saccharomyces cerevisiae is the proposed cause) and yeast sensitivities or dysbiosis would probably want to avoid the probiotic drink. ^{23 24 25}
• Kombucha contains a differing amount of alcohol depending on the fermentation, bottling, and storage processes. Some kombucha can have very little alcohol if any; others can have as much as beer. Some people react negatively to alcohol ingestion because it can deplete glutathione, cause liver oxidative stress, reduce the probiotic microbiome if they have an issue with ALDH2, and alcohol ingestion can cause inflammation in the gastrointestinal system. ²⁶
• People with short bowel syndrome or kidney disease that are more prone to lactic acidosis or D-lactate issues might want to avoid kombucha due to the amount of lactic acid and lactic acid bacteria in the beverage. ^{27 28}
• People with severely compromised immune systems want to avoid fermented beverages and foods like kombucha if possible. Ingestion of fermented foods might be tolerable in minimal amounts with caution. ²⁹
• Kombucha tea can sometimes be contaminated with unwanted microbes that can rarely cause severe digestive issues. Kombucha tea that is homebrewed might be more likely to be contaminated if it is prepared improperly. If your kombucha does not reach a low pH of around two within a day of preparation, mold can form in the tea which can make you very ill. Contamination with Aspergillus, Candida krusei (a multidrug-resistant opportunistic Candida strain has rarely been found in kombucha), and Penicillium have been noted in the literature. All Kombucha that appears moldy, smell rancid, or taste very strongly should be discarded. ^{30 31 32}
• Kombucha has differing amounts of sugar per beverage. Sugar ingestion can be problematic for those with upper gut dysbiosis or diabetes. Many upper gut microbes depend on glucose and fructose for survival and increased simple sugar ingestion might increase their virulence. One study that was performed measuring the sugar content of commercial kombucha products found that many brands were reporting less sugar on the label than what was in the beverages. The study, however, was performed with financial support by a kombucha producing company KeVita (owned by PepsiCo). Therefore more studies need to be performed without possible biases to know for sure. ³³
• Kombucha does have differing amounts of caffeine per brew, but for most, it tends to be on the lower side (10–30 mg). Some people who are very caffeine sensitive might not be able to tolerate kombucha. If you are sensitive to caffeine, kombucha made from green tea (1–5 mg) might be better tolerated, and if you can find, it kombucha made from milk would be the safest. ³⁴

Kombucha may not be able to improve the microbiome and health of everyone that consumes it, but the fermented beverage does have its niche uses. I believe that with someone who has Th1 dominant upper gut dysbiosis with liver and fat digestion issues, consumption of kombucha may improve their overall health. If you are suffering from a Th1 dominant upper gut dysbiosis, then you want to ingest a kombucha that contains the lowest amounts of sugar. Also, some kombucha brands like GT’s and KeVita do use HSO organisms like Bacillus coagulans, so beware of that when you purchase a beverage. Also, watch out for kombucha brands that pasteurize their beverages. Pasteurization may kill most if not all live cultures that you are consuming rendering the “probiotic” drink somewhat useless. If I were going to recommend one brand of kombucha, it would be Townshend’s Brew Dr. Kombucha which is certified organic, low caffeine, low sugar, no HSO’s, and almost nonexistent alcohol content. If you have tried kombucha, let me know your reaction to it in the comment section below. To anyone that wants to try the fermented drink, weigh the above information to see if it is right for you!