Kombucha

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Kombucha including the culture

The name kombucha [(Chinese: chájūn (茶菌), Japanese: kōcha-kinoko (紅茶キノコ), Korean: hongchabeoseotcha (홍차버섯차), Russian: chaynyy grib (чайный гриб)] refers to any of a variety of preparations of fermented, lightly effervescent sweetened black or green tea drinks that are commonly used as functional beverages for their unsubstantiated health benefits. Kombucha is produced by fermenting tea using a "symbiotic 'colony' of bacteria and yeast" (SCOBY). Actual contributing microbial populations in SCOBY cultures vary, but the yeast component generally includes Saccharomyces and other species, and the bacterial component almost always includes Gluconacetobacter xylinus to oxidize yeast-produced alcohols to acetic and other acids.

Beverages referred to as kombucha originated around 5,000 years ago in China, though the English word can only be traced to 1991 and is of uncertain etymology. Historically, kombucha has been home-brewed or locally brewed; in the late 1990s, commercially bottled kombucha became available in North American retail stores.

Although kombucha has been claimed to be a cure for many diseases, and to confer a wide range of health benefits, there is no good evidence to support these claims.[1][2] There are several documented cases of adverse effects related to kombucha drinking, and there is the potential for contamination during home preparation.[2] A systematic review found the mostly unclear benefits of kombucha drinking did not outweigh the known risks, thus should not be recommended for therapeutic use.[1]

History[edit]

Kombucha is reported to have originated around 5,000 years ago in China;[3] based on Qin dynasty records, it was known as "Divine Che" (Divine Tea) and highly valued as an "energizing" and "detoxifying" drink.[3] Then, according to a reported legend, a Korean doctor named Kombu brought the tea to Japan for Emperor Inkyo in 414 AD as an aid for digestive difficulties.[4] The drink spread to east Russia at least as early as 1900, and from there, to Europe.[5]

Etymology[edit]

A SCOBY used for brewing kombucha.

The Japanese name for what English speakers know as kombucha is kōcha kinoko 紅茶キノコ (literally, 'black tea mushroom'), compounding kōcha "black tea" and kinoko "mushroom; toadstool". The Chinese names for kombucha are hóngchájùn 红茶菌 ('red tea fungus'), cháméijūn 茶黴菌 ('tea mold'), or hóngchágū 红茶菇 ('red tea mushroom'), with jūn 'fungus, bacterium or germ' (or jùn 'mushroom'), méijūn 黴菌 'mold or fungus', and 'mushroom'. ("Red tea", 紅茶, in Chinese corresponds to English "black tea".) In Russian, the kombucha culture is called chainyy grib чайный гриб (literally "tea fungus/mushroom"), and the fermented drink is called chainyy grib, grib ("fungus; mushroom"), or chainyy kvas чайный квас ("tea kvass"). In Japan, Konbucha (昆布茶?, "kelp tea") refers to a different beverage made from dried and powdered kombu (an edible kelp from the Laminariaceae family).[6]

The English word kombucha has been in use since at least 1991,[7] and is of uncertain etymology.[8] The American Heritage Dictionary suggests that it is probably from the "Japanese kombucha, tea made from kombu (the Japanese word for kelp perhaps being used by English speakers to designate fermented tea due to confusion or because the thick gelatinous film produced by the kombucha culture was thought to resemble seaweed)."[9]

A 1965 mycological study called kombucha "tea fungus" and listed other names: "teeschwamm, Japanese or Indonesian tea fungus, kombucha, wunderpilz, hongo, cajnij, fungus japonicus, and teekwass".[10] Some further spellings and synonyms include combucha and tschambucco, and haipao, kargasok tea, kwassan, Manchurian fungus or mushroom, spumonto, as well as the misnomers champagne of life, and chai from the sea.[2]

Health claims[edit]

Kombucha has been promoted with claims that it can treat a wide variety of human illnesses including AIDS, cancer, and diabetes, and that it provides other beneficial effects such as stimulation of the immune system, boosting the libido, and reversal of grey hair.[2][4][11] However, evidence of kombucha's beneficial effects in humans is lacking.[2][12] In particular, although animal and in vitro experiments suggest that kombucha consumption may be beneficial, as of 2014 no controlled human trials have been conducted to confirm these conclusions.[11][2][12]

In a systematic review of 2003, Edzard Ernst characterized kombucha as an "extreme example" of an unconventional remedy because of the great disparity between implausible, wide-ranging health claims lacking evidentiary support, and the potential for harm the preparations seem to hold.[1] Ernst concluded that the unsubstantiated list of proposed therapeutic benefits did not outweigh the known risks, and that Kombucha should not be recommended for therapeutic use.[1]

Adverse effects[edit]

Reports of adverse effects related to kombucha consumption are rare. The paucity of reports may be due either to a true lack of adverse effects or these effects being underreported.[1]

Adverse effects associated with kombucha consumption include severe hepatic (liver) and renal (kidney) toxicity as well as metabolic acidosis.[13][14][15] One woman was reported to have died after consuming kombucha though the cause of death was not unequivocally linked to the drink.[16][17]

Some adverse health effects may be due to the acidity of the tea, which can cause acidosis, and brewers have been cautioned to avoid over-fermentation.[18][19] Other adverse health effects may be a result of bacterial or fungal contamination during the brewing process.[19] Some studies have found the hepatotoxin usnic acid in kombucha, although it is not known whether the cases of damage to the liver are due to the usnic acid contamination or to some other toxin.[14][20]

Topical use of the tea has been associated with anthrax infection on the skin in one report, but Kombucha contamination may have occurred during storage.[1]

Due to its microbial sourcing and possible non-sterile packaging, kombucha is not recommended in people with poor immune function,[2] in women who are pregnant or nursing, or in children under 4 years old.[19]

Other uses[edit]

Kombucha culture, when dried, becomes a leather-like textile known as a microbial cellulose that can be molded onto forms to create seamless clothing.[21][22] Using different broth mediums such as coffee, black tea, and green tea to grow the kombucha culture results in different textile colors, although the textile can also by dyed using plant-based dyes.[23] Different growth mediums and dyes also change the textile's feel and texture.[24][23] The kombucha textile is similar to cellulose and is sustainable and compostable. London-based fashion designer Suzanne Lee presented kombucha textiles in shoes and clothing in 2011[25] and in 2014, designer Sacha Laurin debuted a clothing collection made entirely out of kombucha textile.[24]

Composition and properties[edit]

Biological[edit]

Yeast and bacteria in kombucha at 400X

A kombucha culture is a symbiotic culture of bacteria and yeast (SCOBY), similar to mother of vinegar, containing one or more species each of bacteria and yeasts, which form a zoogleal mat[26] known as a "mother."[12] The cultures may contain one or more of the yeasts Saccharomyces cerevisiae, Brettanomyces bruxellensis, Candida stellata, Schizosaccharomyces pombe, and Zygosaccharomyces bailii.[3]

The bacterial component of Kombucha comprises several species, almost always including Gluconacetobacter xylinus (G. xylinus, formerly Acetobacter xylinum), which ferments alcohols produced by the yeasts into acetic and other acids, increasing the acidity and limiting ethanol content.[citation needed] The population of bacteria and yeasts found to produce acetic acid has been reported to increase for the first 4 days of fermentation, decreasing thereafter.[citation needed] G. xylinum has been shown to produce microbial cellulose, and is reportedly responsible for most or all of the physical structure of the "mother", which may have been selectively encouraged over time for firmer (denser) and more robust cultures by brewers.[27][non-primary source needed]

In Chinese, the microbial culture producing Kombucha is called jiaomu in Mandarin and haomo in Cantonese, meaning (Chinese: 酵母; literally: "fermentation mother").[citation needed]

The mixed, presumably symbiotic culture has been further described as being lichenous, in accord with the reported presence of the known lichenous natural product usnic acid, though as of 2015, no report appears indicating the standard cyanobacterial species of lichens in association with Kombucha fungal components.[20]

Chemical[edit]

Sucrose is converted, biochemically, into fructose and glucose, and these into gluconic acid and acetic acid, and these substances are present in the drink.[5] In addition, Kombucha contains enzymes and amino acids, polyphenols, and various other organic acids; the exact quantities of these items vary between preparations. Other specific components include ethanol (see below), glucuronic acid, glycerol, lactic acid, usnic acid (an hepatotoxin, see above), and B-vitamins.[28][29][30] Kombucha has also been found to contain vitamin C.[31]

The alcohol content of the kombucha is usually less than 1% but increases with fermentation time.[19]

Production[edit]

Many families in China are reported to have produced kombucha in their homes,[citation needed] and it was highly popular as a health food during the 1950s and 1960s.[citation needed]

Commercially bottled kombucha became available in the late 1990s.[32] In 2010, elevated alcohol levels were found in many bottled kombucha products, leading retailers including Whole Foods to temporarily pull the drinks from store shelves.[33] In response, kombucha suppliers reformulated their products to have lower alcohol levels.[34] By 2014 US sales of bottled kombucha were $400 million; $350 million of that was earned by Millennium Products, Inc. which sells "GT's Kombucha".[35] In 2014, the market was projected to have 30% growth, and companies that make and sell kombucha formed a trade organization, Kombucha Brewers International.[36]

See also[edit]

References[edit]

  1. ^ a b c d e f Ernst E (2003). "Kombucha: a systematic review of the clinical evidence". Forschende Komplementarmedizin und klassische Naturheilkunde 10 (2): 85–87. doi:10.1159/000071667. PMID 12808367. 
  2. ^ a b c d e f g "Kombucha". Memorial Sloan Kettering Cancer Center. 22 May 2014. Retrieved June 2015. 
  3. ^ a b c Dufresne, C.; Farnworth, E. (2000). "Tea, Kombucha, and health: a review". Food Research International 33 (6): 409–421. doi:10.1016/S0963-9969(00)00067-3. ISSN 0963-9969. 
  4. ^ a b Jarrell J, Cal T, Bennett JW (2000). "The Kombucha Consortia of yeasts and bacteria". Mycologist (Elsevier) 14 (4): 166–170. doi:10.1016/S0269-915X(00)80034-8. 
  5. ^ a b Sreeramulu, G; Zhu, Y; Knol, W (2000). "Kombucha fermentation and its antimicrobial activity". Journal of Agricultural and Food Chemistry 48 (6): 2589–94. doi:10.1021/jf991333m. PMID 10888589. 
  6. ^ Wong, Crystal. (12 July 2007). "U.S. 'kombucha': Smelly and No Kelp". Japan Times. Retrieved 14 June 2015. .
  7. ^ O'Neill, Molly (28 December 1994). "A Magic Mushroom Or a Toxic Fad?". New York Times. Retrieved 14 June 2015. 
  8. ^ Algeo, John; Algeo, Adele (1997). "Among the New Words". American Speech 72 (2): 183–97. doi:10.2307/455789. JSTOR 455789. 
  9. ^ "kombucha". American Heritage Dictionary (Fifth ed.). Houghton Mifflin Harcourt Publishing Company. 2015. Retrieved 27 June 2015. 
  10. ^ Hesseltine, C. W. (1965). "A Millennium of Fungi, Food, and Fermentation". Mycologia 57 (2): 149–97. doi:10.2307/3756821. JSTOR 3756821. PMID 14261924. 
  11. ^ a b Vīna, Ilmāra; Semjonovs, Pāvels; Linde, Raimonds; Deniņa, Ilze (2014). "Current evidence on physiological activity and expected health effects of kombucha fermented beverage". Journal of Medicinal Food (Review) 17 (2): 179–88. doi:10.1089/jmf.2013.0031. PMID 24192111. 
  12. ^ a b c Jayabalan, Rasu (21 June 2014). "A Review on Kombucha Tea—Microbiology, Composition, Fermentation, Beneficial Effects, Toxicity, and Tea Fungus". Comprehensive Reviews in Food Science and Food Safety 13 (4): 538–550. doi:10.1111/1541-4337.12073. Retrieved 17 July 2015. 
  13. ^ Dasgupta, Amitava (2011). Effects of Herbal Supplements on Clinical Laboratory Test Results. Berlin, Germany: Walter de Gruyter. pp. 24, 108, 112. ISBN 978-3-1102-4561-5. 
  14. ^ a b Dasgupta, Amitava (2013). "Effects of herbal remedies on clinical laboratory tests". In Dasgupta, Amitava; Sepulveda, Jorge L. Accurate Results in the Clinical Laboratory: A Guide to Error Detection and Correction. Amsterdam, NH: Elsevier. pp. 78–79. ISBN 978-0-1241-5783-5. 
  15. ^ Abdualmjid, Reem J; Sergi, Consolato (2013). "Hepatotoxic Botanicals—An Evidence-based Systematic Review". Journal of Pharmacy & Pharmaceutical Sciences 16 (3): 376–404. PMID 24021288. 
  16. ^ Bryant BJ, Knights KM (2011). Chapter 3: Over-the-counter Drugs and Complementary Therapies. Pharmacology for Health Professionals (3rd ed.) (Elsevier Australia). p. 78. ISBN 978-0-7295-3929-6. Kombucha has been associated with illnesses and death. A tea made from Kombucha is said to be a tonic, but several people have been hospitalised and at least one woman died after taking this product. The cause could not be directly linked to Kombucha, but several theories were offered, e.g. The tea might have reacted with other medications that the woman was taking, or bacteria might grow in the Kombucha liquid and, in patients with suppressed immunity, might prove to be fatal. 
  17. ^ Unexplained Severe Illness Possibly Associated with Consumption of Kombucha Tea -- Iowa, 1995 (Report). Morbidity and Mortality Weekly Report 44 (48). CDC. 8 December 1995. pp. 892–893,899–900. Retrieved 18 July 2015. 
  18. ^ Nummer, Brian A. (November 2013). "Kombucha Brewing Under the Food and Drug Administration Model Food Code: Risk Analysis and Processing Guidance". Journal of Environmental Health 76 (4): 8–11. PMID 24341155. 
  19. ^ a b c d Food Safety Assessment of Kombucha Tea Recipe and Food Safety Plan (PDF) (Report). Food Issue, Notes From the Field. British Columbia (BC) Centre for Disease Control. 27 January 2015. Retrieved 1 July 2015. 
  20. ^ a b "Drug record, Usnic acid (Usnea species)". LiverTox. National Library of Medicine, National Institutes of Health. 23 June 2015. Retrieved 2 July 2015. 
  21. ^ Grushkin, Daniel (17 February 2015). "Meet the Woman Who Wants to Grow Clothing in a Lab". Popular Science. Retrieved 18 June 2015. 
  22. ^ Oiljala, Leena (9 September 2014). "BIOCOUTURE Creates Kombucha Mushroom Fabric For Fashion & Architecture". Pratt Institute. Retrieved 18 June 2015. 
  23. ^ a b Hinchliffe, Jessica (25 September 2014). "'Scary and gross': Queensland fashion students grow garments in jars with kombucha". ABCNet.net.au. Retrieved 18 June 2015. 
  24. ^ a b Mandelkern, India (22 Nov 2013). "Can Kombucha Couture Save the World?". Huffington Post. Retrieved 18 June 2015. 
  25. ^ "Suzanne Lee: Grow your own clothes". TED2011. March 2011. 
  26. ^ Blanc, Phillipe J (February 1996). "Characterization of the tea fungus metabolites". Biotechnology Letters 18 (2): 139–142. doi:10.1007/BF00128667. Retrieved 17 July 2015. 
  27. ^ Nguyen, VT; Flanagan, B; Gidley, MJ; Dykes, GA (2008). "Characterization of cellulose production by a gluconacetobacter xylinus strain from kombucha". Current Microbiology 57 (5): 449–53. doi:10.1007/s00284-008-9228-3. PMID 18704575. [non-primary source needed]
  28. ^ Teoh, AL; Heard, G; Cox, J (2004). "Yeast ecology of kombucha fermentation". International Journal of Food Microbiology 95 (2): 119–26. doi:10.1016/j.ijfoodmicro.2003.12.020. PMID 15282124. 
  29. ^ Dufresne, C; Farnworth, E (2000). "Tea, kombucha, and health: A review". Food Research International 33 (6): 409. doi:10.1016/S0963-9969(00)00067-3. 
  30. ^ Velicanski, A; Cvetkovic, D; Markov, S; Tumbas, V et al. (2007). "Antimicrobial and antioxidant activity of lemon balm Kombucha". Acta Periodica Technologica (38): 165–72. doi:10.2298/APT0738165V. 
  31. ^ Bauer-Petrovska, B; Petrushevska-Tozi, L (2000). "Mineral and water soluble vitamin content in the kombucha drink". International Journal of Food Science & Technology 35 (2): 201–5. doi:10.1046/j.1365-2621.2000.00342.x. 
  32. ^ Wollan, Malia (24 March 2010). "A Strange Brew May Be a Good Thing". NYTimes. Retrieved 18 June 2015. 
  33. ^ Rothman, Max (2 May 2013). "‘Kombucha Crisis’ Fuels Progress". BevNET. Retrieved 18 June 2015. 
  34. ^ Crum, Hannah (23 August 2011). "The Kombucha Crisis: One Year Later". BevNET. Retrieved 27 June 2015. 
  35. ^ Narula, Svati Kirsten (26 March 2015). "The American kombucha craze, in one home-brewed chart". Quartz. Retrieved 27 June 2015. 
  36. ^ Carr, Coeli (9 August 2014). "Kombucha cha-ching: A probiotic tea fizzes up strong growth". CNBC. Retrieved 27 June 2015.