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


Background


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.


Science 


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

Safety, interactions, legal issues


No human clinical trials have investigated either the safety or the efficacy of kombucha. Lead poisoning has been reported in instances of kombucha tea being fermented in lead-glazed ceramic containers.8 

Fungal and bacterial contaminants are common, with more than 20 cases of cutaneous anthrax as well as liver damage and allergic reactions reported.9 

Other harmful contaminants found in kombucha include such molds as Aspergillus. Excessive consumption has resulted in life-threatening metabolic acidosis.10

In one class-action lawsuit, consumers have alleged that a major manufacturer of commercial kombucha products labeled the drink with specific claims of near-miraculous health benefits.11 

The U.S. Bureau of Alcohol, Tobacco, and Firearms is investigating claims that kombucha products are alcoholic.12 Multiple samples analyzed contained 0.5% alcohol by volume, thereby qualifying it as an alcoholic beverage.12

Extreme caution should be used in the consumption of kombucha tea. Children, pregnant or nursing women, and immunocompromised persons should never ingest this product.


Cost, how supplied, dose


Homemade kombucha is extremely inexpensive because its only ingredients are tea, sugar, and yeast. Commercial products retail for about $4 per 16-oz bottle. For people just beginning the kombucha adventure, it is recommended that they start off with just 1 oz to 2 oz per day.1

Summary

In spite of many favorable testimonials regarding kombucha consumption, insufficient evidence exists to support recommending the use of this product. The reports of toxicity are significant enough to warn patients against buying or fermenting their own supply. 

Sherril Sego, FNP-C, DNP, is a staff clinician at the VA Hospital in Kansas City, Mo., where she practices adult medicine and women’s health. She also teaches at the nursing schools of the University of Missouri and the University of Kansas.

References


  1. American Cancer Society. Kombucha tea. Available at www.cancer.org/treatment/treatmentsandsideeffects/complementaryandalternativemedicine/dietandnutrition/kombucha-tea. 

  2. Sreeramulu G, Zhu Y, Knol W. Kombucha fermentation and its antimicrobial activity. J Agric Food Chem. 2000;48(6):2589-2594.

  3. LeBlanc CS. The kombucha tea recall. Health Law Perspectives. 2010. Available at www.law.uh.edu/healthlaw/perspectives/homepage.asp
  4. Battikh H, Chaieb K, Bakhrouf A, Ammar E. Antibacterial and antifungal activities of black and green kombucha teas. J Food Biochemistry. 2012;37(2):231-236.

  5. Greenwalt CJ, Ledford RA, Steinkraus KH. Determination and characterization of the anti-microbial activity of the fermented tea Kombucha. Happy Herbalist. Available at
  6. J Sci Food Agric. 2014;94(2):265-272.

  7. Wang Y, Ji B, Wu W, et al. Hepatoprotective effects of kombucha tea: identification of functional strains and quantification of functional components. J Sci Food Agric. 2014;94(2):265-272.
  8. Bhattacharya S, Gachhui R, Sil P. Hepatoprotective properties of kombucha tea against TBHP-induced oxidative stress via suppression of mitochondria dependent apoptosis.  Pathophysiology. 2011;18(3):221-234. Available at www.pathophysiologyjournal.com/article/S0928-4680(11)00003-4/fulltext.

  9. Phan TG, Estell J, Duggin G, et al. Lead poisoning from drinking Kombucha tea brewed in a ceramic pot. Med 
J Aust. 1998;169(11-12):644-646.

  10. adjadi J. Cutaneous anthrax associated with the Kombucha “mushroom” in Iran. JAMA. 1998;280(18):1567-1568.

  11. Centers for Disease Control and Prevention. Unexplained severe illness possibly associated with consumption of kombucha tea—Iowa, 1995. MMWR. 1995;44(48):892-893, 899-900.
  12. Mirando K. Gretchen Patch v. Millennium Products, Inc., Civil Action Case No. 10-CV-7244 ODW (Ex). Available from: www.topclassactions.com/lawsuit-settlements/lawsuit-news/829-kombucha-tea-class-action-lawsuit
  13. Bureau of Alcohol, Tobacco, and Firearms. Kombucha FAQS. Available at www.ttb.gov/faqs/kombucha-faqs.shtml.

All electronic documents accessed July 3, 2014