Kombucha

Kombucha likely originated in the Bohai Sea region of China. It spread to Russia before reaching Europe and gained popularity in the United States in the early 21st century.{{cite journal |last1=Sreeramulu |first1=G |last2=Zhu |first2=Y |last3=Knol |first3=W |year=2000 |title=Kombucha fermentation and its antimicrobial activity |url=https://research.kombuchabrewers.org/wp-content/uploads/kk-research-files/kombucha-fermentation-and-its-antimicrobial-activity.pdf |journal=Journal of Agricultural and Food Chemistry |volume=48 |issue=6 |pages=2589–2594 |bibcode=2000JAFC...48.2589S |doi=10.1021/jf991333m |pmid=10888589 |quote=It originated in northeast China (Manchuria) and later spread to Russia and the rest of the world.}}{{cite web |author=Hamblin, James |date=8 December 2016 |title=Is Fermented Tea Making People Feel Enlightened Because of ... Alcohol? |url=https://www.theatlantic.com/health/archive/2016/12/the-promises-of-kombucha/509786/ |access-date=26 November 2017 |publisher=The Atlantic}}{{cite book |author=Sandor Ellix Katz |url=https://books.google.com/books?id=TjXEAgAAQBAJ&pg=PA167 |title=The Art of Fermentation: An In-depth Exploration of Essential Concepts and Processes from Around the World |publisher=Chelsea Green Publishing |year=2012 |isbn=978-1-60358-286-5 |pages=167–}} In the intervening years, its popularity in the West eclipsed its popularity in most parts of China, where it remains less known,{{cite web | last=Interns | first=Our | title=The Cloudy Origins of Kombucha | website=Smithsonian Center for Folklife and Cultural Heritage | date=2019-04-15 | url=https://folklife.si.edu/magazine/cloudy-origins-of-kombucha | access-date=2025-04-14}} though consumption is increasing in many East Asian countries.{{cite web | last=Ahuja | first=Kunal | last2=Insights | first2=Global Market | title=Kombucha Industry Expands in the Asia-Pacific Region | website=World Tea News | date=2021-03-03 | url=https://www.worldteanews.com/products%20&%20equipment/kombucha-industry-expands-asia-pacific-region | access-date=2025-04-14}} With an alcohol content under 0.5%, it is not federally regulated in the U.S.{{Cite web |title=Hard Kombucha Is Super Trendy, but Is It Good for You? We Asked Nutritionists |url=https://www.health.com/food/hard-kombucha |website=Health.com}}{{Cite web |title=Hard Kombucha Is the New Trendy Beverage You Should Try |url=https://www.bhg.com/recipes/trends/hard-kombucha/ |website=Better Homes & Gardens}}

Prior to 2015, some commercially available kombucha brands were found to contain alcohol content exceeding this threshold, sparking the development of new testing methods.{{cite news|url= https://apnews.com/23ca8b0eafd740838f7fd379eba32b42/kombucha-sales-boom-makers-ask-feds-new-alcohol-test|title= As kombucha sales boom, makers ask feds for new alcohol test|publisher= Associated Press|author =Wyatt, Kristen|date= 12 October 2015|access-date= 26 November 2017}} With rising popularity in developed countries in the early 21st century, kombucha sales increased after it was marketed as an alternative to beer and other alcoholic drinks in restaurants and pubs.{{Cite news|url= https://www.theguardian.com/food/2018/oct/11/kombucha-can-the-fermented-drink-compete-with-beer-at-the-bar|title= Kombucha: can the fermented drink compete with beer at the bar?|last= Fleming|first= Amy|date= 11 October 2018|newspaper= The Guardian|language= en|access-date= 11 October 2018}}

According to the market research firm Grand View Research,{{clarify|date=June 2022}} kombucha had a global market size of {{US$|1.67}}{{thinsp}}billion {{as of|lc=yes|2019}}, and this is expected to grow to {{US$|9.7}}{{thinsp}}billion by 2030.{{cite web |publisher=Grandview Research |url=https://www.grandviewresearch.com/industry-analysis/kombucha-market |date=February 2020 |title=Kombucha Market Size, Share & Trends Analysis Report By Flavor (Original, Flavored), By Distribution Channel (Supermarkets, Health Stores, Online Stores), By Region, And Segment Forecasts, 2020 – 2027}}

The etymology of kombucha is uncertain, but it is believed to be a misapplied loanword from Japanese.{{cite journal |last1=Algeo |first1=John |last2=Algeo |first2=Adele |year=1997 |title=Among the New Words |journal=American Speech |volume=72 |issue=2 |pages=183–97 |doi=10.2307/455789 |jstor=455789}} English speakers may have confused the Japanese word konbucha with {{nihongo3|'black tea mushroom'|紅茶キノコ|kōcha kinoko}}, popularized around 1975.{{cite news |last=Wong |first=Crystal |date=12 July 2007 |title=U.S. 'kombucha': Smelly and No Kelp |url=http://www.japantimes.co.jp/news/2007/07/12/national/u-s-kombucha-smelly-and-no-kelp/ |access-date=14 June 2015 |work=Japan Times |archive-date=21 June 2013 |archive-url=https://web.archive.org/web/20130621000130/http://www.japantimes.co.jp/news/2007/07/12/national/u-s-kombucha-smelly-and-no-kelp/ |url-status=bot: unknown }}.(Internet Archive){{Cite web |last= |first= |title=紅茶キノコ(こうちゃキノコ)とは？ 意味や使い方 |trans-title=What is "red tea mushroom"? – meaning and usage |url=https://kotobank.jp/word/%E7%B4%85%E8%8C%B6%E3%82%AD%E3%83%8E%E3%82%B3-163231 |access-date=2024-05-20 |website=Kotobank |language=ja}}

In Japanese, the term {{nihongo3|'kelp tea'|昆布茶|konbu-cha}} refers to a kelp tea made with konbu (an edible kelp from the family Laminariaceae) and is a completely different beverage from the fermented tea usually associated with kombucha elsewhere in the world.[https://www.cbc.ca/radio/costofliving/a-cow-worth-140-000-plus-whether-kombucha-is-bacteria-worth-billions-or-just-seaweed-tea-1.5378997/how-kombucha-went-from-seaweed-tea-in-japan-to-a-hit-in-north-america-1.5379001 How kombucha went from seaweed tea in Japan to a hit in North America]

Merriam-Webster's Dictionary suggests kombucha in English arose from misapplication of Japanese words like {{Transliteration|ja|konbucha}}, {{Transliteration|ja|kobucha}} 'tea made from kelp', {{Transliteration|ja|konbu}}, from {{Transliteration|ja|kobu}} 'kelp', + {{Transliteration|ja|cha}} 'tea'.{{Cite web |title=Definition of KOMBUCHA |url=https://www.merriam-webster.com/dictionary/kombucha |access-date=29 May 2019 |website=www.merriam-webster.com |language=en}} The American Heritage Dictionary notes the term might have originated from the belief that the gelatinous film of kombucha resembled seaweed.{{cite encyclopedia |title=Kombucha |encyclopedia=American Heritage Dictionary |publisher=Houghton Mifflin Harcourt Publishing Company |url=http://www.thefreedictionary.com/kombucha |access-date=27 June 2015 |date=2015 |edition=Fifth}}

The first known use in the English language of the word appeared in the British Chemical Abstracts in 1928.{{Cite journal|last=Clutterbuck|first=P. W.|date=January 1928|title="Kombucha." I and II.|journal=British Chemical Abstracts|language=en|pages=330|url=https://archive.org/details/1928A/1928_A/page/330/}}

File:Kombuchacultsm.jpg

File:SCOBY mushroom.jpg used for brewing kombucha]]

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{{cite journal|last1=Blanc|first1=Phillipe J|title=Characterization of the tea fungus metabolites|journal=Biotechnology Letters|date=February 1996|volume=18|issue=2|pages=139–142|doi=10.1007/BF00128667|s2cid=34822312}} known as a "mother".{{cite journal|last1=Jayabalan|first1=Rasu|title=A Review on Kombucha Tea—Microbiology, Composition, Fermentation, Beneficial Effects, Toxicity, and Tea Fungus|journal=Comprehensive Reviews in Food Science and Food Safety|date=21 June 2014|volume=13|issue=4|pages=538–550|doi=10.1111/1541-4337.12073|pmid=33412713|s2cid=62789621 |doi-access=}} There is a broad spectrum of yeast species spanning several genera reported to be present in kombucha cultures, including species of Zygosaccharomyces, Candida, Kloeckera/Hanseniaspora, Torulaspora, Pichia, Brettanomyces/Dekkera, Saccharomyces, Lachancea, Saccharomycoides, Schizosaccharomyces, Kluyveromyces, Starmera, Eremothecium, Merimbla, Sugiyamaella.{{Cite journal|last1=Villarreal-Soto|first1=Silvia Alejandra|last2=Beaufort|first2=Sandra|last3=Bouajila|first3=Jalloul|last4=Souchard|first4=Jean-Pierre|last5=Taillandier|first5=Patricia|date=2018|title=Understanding Kombucha Tea Fermentation: A Review|journal=Journal of Food Science|language=en|volume=83|issue=3|pages=580–588|doi=10.1111/1750-3841.14068|pmid=29508944|issn=1750-3841|url=http://oatao.univ-toulouse.fr/21134/1/VillarrealSoto_21134.pdf|doi-access=free|archive-date=19 August 2019|access-date=24 September 2019|archive-url=https://web.archive.org/web/20190819105501/http://oatao.univ-toulouse.fr/21134/1/VillarrealSoto_21134.pdf|url-status=dead}}{{Cite web|url=https://www.ombucha.co.uk/faq/|title=Faq Archive - OMbucha Kombucha {{!}} Hand Brewed With Loving Care|language=en-GB|access-date=31 July 2019|archive-date=31 July 2019|archive-url=https://web.archive.org/web/20190731160738/https://www.ombucha.co.uk/faq/|url-status=dead}}{{Cite journal |last1=Chakravorty |first1=Somnath |last2=Bhattacharya |first2=Semantee |last3=Chatzinotas |first3=Antonis |last4=Chakraborty |first4=Writachit |last5=Bhattacharya |first5=Debanjana |last6=Gachhui |first6=Ratan |date=2 March 2016 |title=Kombucha tea fermentation: Microbial and biochemical dynamics |url=https://www.sciencedirect.com/science/article/pii/S0168160515301951 |journal=International Journal of Food Microbiology |language=en |volume=220 |pages=63–72 |doi=10.1016/j.ijfoodmicro.2015.12.015 |pmid=26796581 |issn=0168-1605}}

The bacterial component of kombucha comprises several species, almost always including the acetic acid bacteria Komagataeibacter xylinus (formerly Gluconacetobacter xylinus), which ferments alcohols produced by the yeasts into acetic and other acids, increasing the acidity and limiting ethanol content.{{cite journal|title=Fermentation and metabolic characteristics of Gluconacetobacter oboediens for different carbon sources|journal=Applied Microbiology and Biotechnology|volume=87|issue=1|pages=127–136|doi=10.1007/s00253-010-2474-x|pmid=20191270|year=2010|last1=Sarkar|first1=Dayanidhi|last2=Yabusaki|first2=Masahiro|last3=Hasebe|first3=Yuta|last4=Ho|first4=Pei Yee|last5=Kohmoto|first5=Shuji|last6=Kaga|first6=Takayuki|last7=Shimizu|first7=Kazuyuki|s2cid=11657067}}{{citation needed|date=July 2015}} 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.Kombucha Fermentation and Its Antimicrobial Activity

Guttapadu Sreeramulu, Yang Zhu,* and Wieger Knol

Journal of Agricultural and Food Chemistry 2000 48 (6), 2589–2594

{{doi|10.1021/jf991333m}} K. xylinus produces bacterial 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.{{cite journal |last1= Nguyen |first1= VT |last2= Flanagan |first2= B |last3= Gidley |first3= MJ |last4= Dykes |first4= GA |year= 2008 |title= Characterization of cellulose production by a gluconacetobacter xylinus strain from kombucha |journal= Current Microbiology |volume= 57 |issue= 5 |pages= 449–53 |doi= 10.1007/s00284-008-9228-3|pmid= 18704575|s2cid= 1414305 }}{{primary source inline|date=July 2015}} The highest diversity of kombucha bacteria was found to be on the 7th day of fermentation with the diversity being less in the SCOBY. Acetobacteraceae dominate 88 percent of the bacterial community of the SCOBY. The acetic acid bacteria in kombucha are aerobic, meaning that they require oxygen for their growth and activity. Hence, the bacteria initially migrate and assemble at the air interface, followed by the excretion of bacterial cellulose after about 2 days.{{cite journal |last1=Bertsch |first1=Pascal |last2=Etter |first2=Danai |last3=Fischer |first3=Peter |title=Transient in situ measurement of kombucha biofilm growth and mechanical properties |journal=Food & Function |date=2021 |volume=12 |issue=9 |pages=4015–4020 |doi=10.1039/D1FO00630D |pmid=33978026 |doi-access=free |hdl=20.500.11850/485857 |hdl-access=free }}

The mixed, presumably mutualistic 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.

Kombucha is made by adding the kombucha culture into a broth of sugared tea. The sugar serves as a nutrient for the SCOBY that allows for bacterial growth in the tea.{{citation needed|date=April 2024}} Sucrose is converted, biochemically, into fructose and glucose, and these into gluconic acid and acetic acid. In addition, kombucha contains enzymes and amino acids, polyphenols, and various other organic acids which vary between preparations.{{citation needed|date=April 2024}}

Other specific components include ethanol (see below), glucuronic acid, glycerol, lactic acid, and usnic acid (a hepatotoxin, see above).{{cite journal |last1= Teoh |first1= AL |last2= Heard |first2= G |last3= Cox |first3= J |year= 2004 |title= Yeast ecology of kombucha fermentation |journal= International Journal of Food Microbiology |volume= 95 |issue= 2 |pages= 119–26 |pmid= 15282124|doi= 10.1016/j.ijfoodmicro.2003.12.020}}{{cite journal |last1= Dufresne |first1= C |last2= Farnworth |first2= E |year= 2000 |title= Tea, kombucha, and health: A review |journal= Food Research International |volume= 33 |issue= 6 |pages= 409–421 |doi= 10.1016/S0963-9969(00)00067-3}}{{cite journal |last1= Velicanski |first1= A |last2= Cvetkovic |first2= D |last3= Markov |first3= S |last4= Tumbas |first4= V |last5= Savatovic |first5= S |display-authors= 4 |year= 2007 |title= Antimicrobial and antioxidant activity of lemon balm Kombucha |journal= Acta Periodica Technologica |issue= 38 |pages= 165–72|doi= 10.2298/APT0738165V|doi-access= free }}

The alcohol content of kombucha is usually less than 0.5%, but increases with extended fermentation times. Some tests have found commercial kombuchas with a range of alcohol contents ranging from undetectable to 4%.{{cite web | last=Eykelbosh | first=Angela | title=National Collaborating Centre for Environmental Health | website=NCCEH | date=August 13, 2020 | url=https://ncceh.ca/resources/blog/kombucha-kick-ethanol-content-retail-brews | access-date=March 27, 2025}} The concentration of alcohol specifically ethanol increases initially but then begins to decrease when acetic acid bacteria use it to produce acetic acid. Over-fermentation generates high amounts of acids similar to vinegar. The pH of the drink is typically about 3.5.

Kombucha tea is 95% water and contains 4% carbohydrates and several B vitamins, such as thiamin, riboflavin, niacin, and vitamin B₆.{{cite web |title=Nutrient content of kombucha tea per 100 ml |url=https://fdc.nal.usda.gov/food-details/2710509/nutrients |publisher=FoodData Central, US Department of Agriculture |access-date=2 November 2024 |date=31 October 2024}}

File:Kombucha Store Shelves.jpg

Kombucha can be prepared at home or commercially. It is made by dissolving sugar in non-chlorinated boiling water. Tea leaves are then steeped in the hot sugar water and discarded. The sweetened tea is cooled and the SCOBY culture is added. The mixture is then poured into a sterilized beaker along with previously fermented kombucha tea to lower the pH. This technique is known as "backslopping".{{Cite book|last=Redzepi|first=René|url=https://www.worldcat.org/oclc/1028603169|title=The Noma guide to fermentation: foundations of flavor|date=2018|others=David Zilber, Evan Sung, Paula Troxler|isbn=978-1-57965-718-5|location=New York, NY|pages=33|oclc=1028603169}} The container is covered with a paper towel or breathable fabric to prevent insects, such as fruit flies, from contaminating the kombucha.

The tea is left to ferment for a period of up to 10 to 14 days at room temperature (18 °C to 26 °C). A new "daughter" SCOBY will form on the surface of the tea to the diameter of the container. After fermentation is completed, the SCOBY is removed and stored along with a small amount of the newly fermented tea. The remaining kombucha is strained and bottled for a secondary ferment for a few days or stored at a temperature of 4 °C.

File:Kombucha jar.jpg

Commercially bottled kombucha became available in the late 1990s.{{cite news|url=https://www.nytimes.com/2010/03/25/fashion/25Tea.html?_r=1|title=A Strange Brew May Be a Good Thing |last=Wollan|first=Malia|date=24 March 2010|publisher=NYTimes|access-date=18 June 2015}} In 2010, elevated alcohol levels were found in many bottled kombucha products, leading retailers including Whole Foods to pull the drinks from store shelves temporarily.{{cite news|url=http://www.bevnet.com/news/2013/kombucha-crisis-fuels-progress/|title='Kombucha Crisis' Fuels Progress|last=Rothman|first=Max|date=2 May 2013|publisher=BevNET|access-date=18 June 2015}} In response, kombucha suppliers reformulated their products to have lower alcohol levels.{{cite news |url=http://www.bevnet.com/news/2011/the-kombucha-crisis-one-year-later |title=The Kombucha Crisis: One Year Later |last=Crum |first=Hannah |date=23 August 2011 |access-date=27 June 2015 |publisher=BevNET}}

By 2014, US sales of bottled kombucha were $400 million, $350 million of which was by Millennium Products, Inc. which sells GT's Kombucha.{{cite web |url=http://qz.com/368513/the-american-kombucha-craze-in-one-home-brewed-chart/ |title=The American kombucha craze, in one home-brewed chart |last=Narula |first=Svati Kirsten |website=Quartz |date=26 March 2015 |access-date=27 June 2015}} In 2014, several companies that make and sell kombucha formed a trade organization, Kombucha Brewers International.{{cite news |url=https://www.cnbc.com/2014/08/08/kombucha-cha-ching-a-probiotic-tea-fizzes-up-strong-growth.html |title=Kombucha cha-ching: A probiotic tea fizzes up strong growth |last=Carr |first=Coeli |publisher=CNBC |date=9 August 2014 |access-date=27 June 2015}} In 2016, PepsiCo purchased kombucha maker KeVita for approximately $200 million.{{cite news|last1=Esterl|first1=Mike|title=Slow Start for Soda Industry's Push to Cut Calories|url=https://www.wsj.com/articles/slow-start-for-soda-industrys-push-to-cut-calories-1479837601|access-date=24 November 2016|newspaper=Wall Street Journal|date=23 November 2016}} In the US, sales of kombucha and other fermented drinks rose by 37 percent in 2017. Beer companies like Full Sail Brewing Company and Molson Coors Beverage Company produce kombucha by themselves or via subsidiaries.

As of 2021, the drink had some popularity in India's National Capital Region, partly due to its success in the west.{{cite web |last1=Roy |first1=Dyuti |title=How Kombucha tea is becoming a beverage of choice for many in Delhi-NCR |url=https://www.newindianexpress.com/lifestyle/food/2021/nov/21/how-kombucha-tea-is-becoming-abeverage-of-choice-for-many-in-delhi-ncr-2386129.html |website=The New Indian Express |access-date=21 April 2022 |date=21 November 2021}}

Some commercial kombucha producers sell what they call "hard kombucha" with an alcohol content of over 5 percent.{{cite news|last1=Judkis|first1=Maura|date=13 December 2018|title=Is boozy kombucha good for you? It's getting so popular it might not matter.|newspaper=The Washington Post|url=https://www.washingtonpost.com/news/voraciously/wp/2018/12/13/is-boozy-kombucha-good-for-you-its-getting-so-popular-it-might-not-matter/?noredirect=on|access-date=12 September 2019}}{{cite news|last1=Casey|first1=Michael|date=3 July 2019|title=New in brew: Hard kombucha|publisher=Boulder Weekly|url=https://www.boulderweekly.com/cuisine/drink/new-in-brew-hard-kombucha/|access-date=12 September 2019}}

File:300ml glass of kombucha with ice.png

Kombucha is promoted with many claims for health benefits, from alleviating hemorrhoids to combating cancer.{{cite news| newspaper=New York Times |date=16 October 2019 |vauthors=MacKeen D |url=https://www.nytimes.com/2019/10/16/style/self-care/kombucha-benefits.html |title=Are There Benefits to Drinking Kombucha?}} Although people may drink kombucha for such supposed health effects (attributed first to the protective impact of tea itself, and to fermentation products including glucuronic acid, acetic acid, polyphenols, phenols, and B-complex vitamins such as folic acid {{cite journal |vauthors= Baschali A, Tsakalidou E, Kyriacou A, Karavasiloglou N, Matalas AL |title= Traditional low-alcoholic and non-alcoholic fermented beverages consumed in European countries: a neglected food group |journal= Nutrition Research Reviews |volume=30 |pages=1-15 |date=January 2017 |pmid=28115036 | doi=10.1017/S0954422416000202 |doi-access=free }}{{rp|15}}), there is no clinical proof that it provides any benefit.{{cite journal|last1=Villarreal-Soto|first1=Silvia Alejandra|last2=Beaufort|first2=Sandra|last3=Bouajila|first3=Jalloul|last4=Souchard|first4=Jean-Pierre|last5=Taillandier|first5=Patricia|year=2018|title=Understanding Kombucha Tea Fermentation: A Review|journal=Journal of Food Science|volume=83|issue=3|pages=580–588|doi=10.1111/1750-3841.14068|issn=0022-1147|pmid=29508944|url=http://oatao.univ-toulouse.fr/21134/1/VillarrealSoto_21134.pdf|doi-access=free|archive-date=19 August 2019|access-date=24 September 2019|archive-url=https://web.archive.org/web/20190819105501/http://oatao.univ-toulouse.fr/21134/1/VillarrealSoto_21134.pdf|url-status=dead}}{{cite journal |vauthors=Kapp JM, Sumner W |title=Kombucha: a systematic review of the empirical evidence of human health benefit |journal=Annals of Epidemiology |volume=30 |pages=66–70 |date=February 2019 |pmid=30527803 |doi=10.1016/j.annepidem.2018.11.001 |doi-access=free }} In a 2003 review, physician Edzard Ernst characterized kombucha as an "extreme example" of an unconventional remedy because of the disparity between implausible, wide-ranging health claims and the potential risks of the product. It concluded that the proposed, unsubstantiated therapeutic claims did not outweigh known risks, and that kombucha should not be recommended for therapeutic use, being in a class of "remedies that only seem to benefit those who sell them".{{cite journal|author=Ernst E|title=Kombucha: a systematic review of the clinical evidence|url=https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0020339/|journal=Forschende Komplementärmedizin und Klassische Naturheilkunde|year=2003|volume=10|issue=2|pages=85–87|doi=10.1159/000071667|pmid=12808367|s2cid=42348141}}

Reports of adverse effects related to kombucha consumption are rare, but may be underreported, according to a 2003 review. The American Cancer Society said in 2009 that "serious side effects and occasional deaths have been associated with drinking Kombucha tea."{{cite book|publisher=American Cancer Society|title=American Cancer Society Complete Guide to Complementary and Alternative Cancer Therapies|chapter-url=https://archive.org/details/americancancerso0000unse|chapter-url-access=registration|edition=2nd|year=2009|isbn=9780944235713|location=New York |veditors=Russell J, Rovere A|pages=[https://archive.org/details/americancancerso0000unse/page/629 629–633]|chapter=Kombucha tea|quote=Serious side effects and occasional deaths have been associated with drinking Kombucha tea}} Because kombucha is a commonly homemade fermentation, caution should be taken because pathogenic microorganisms can contaminate the tea during preparation. The risk of proliferation of bacteria associated with botulinum toxin is one reason that the pH of kombucha must be low, as Clostridium botulinum struggles to proliferate below pH 4.6.{{Cite| publisher = Maricopa County Environmental Services| title = Kombucha| date = 2017| url = https://www.maricopa.gov/DocumentCenter/View/75807/Kombucha-Guidance-PDF}}{{cite web | title=Botulism | website=

World Health Organization (WHO)

| date=September 25, 2023 | url=https://www.who.int/news-room/fact-sheets/detail/botulism | ref={{sfnref|

World Health Organization (WHO)

|2023}} | access-date=March 27, 2025}}

Adverse effects associated with kombucha consumption may include severe hepatic (liver) and renal (kidney) toxicity as well as metabolic acidosis.{{cite book|title=Effects of Herbal Supplements on Clinical Laboratory Test Results|last=Dasgupta|first=Amitava|url=https://books.google.com/books?id=Ts9WFyHtODMC|year=2011|pages=24, 108, 112|publisher=Walter de Gruyter|location=Berlin, Germany|isbn=978-3-1102-4561-5}}{{cite journal|title=Hepatotoxic Botanicals—An Evidence-based Systematic Review|journal=Journal of Pharmacy & Pharmaceutical Sciences |last1=Abdualmjid|first1=Reem J|last2=Sergi|first2=Consolato|year=2013|volume=16|issue=3|pages=376–404|pmid=24021288|doi=10.18433/J36G6X |doi-access=free}}

Some adverse health effects may arise from the acidity of the tea causing acidosis, and brewers are cautioned to avoid over-fermentation.{{cite web|url=https://www.mskcc.org/cancer-care/integrative-medicine/herbs/kombucha|title=Kombucha|date=22 May 2014|publisher=Memorial Sloan Kettering Cancer Center|access-date=1 June 2015}}{{cite journal|last=Nummer|first=Brian A.|title=Kombucha Brewing Under the Food and Drug Administration Model Food Code: Risk Analysis and Processing Guidance|journal=Journal of Environmental Health|volume=76|issue=4|pages=8–11|date=November 2013|pmid=24341155}} Other adverse effects may be a result of bacterial or fungal contamination during the brewing process. Some studies have found the hepatotoxin usnic acid in kombucha, although it is not known whether the cases of liver damage are due to usnic acid or to some other toxin.{{cite book |title=Accurate Results in the Clinical Laboratory: A Guide to Error Detection and Correction|editor-last1=Dasgupta|editor-first1=Amitava|editor-last2=Sepulveda|editor-first2=Jorge L.|chapter=Effects of herbal remedies on clinical laboratory tests|last=Dasgupta|first=Amitava|pages=78–79|chapter-url=https://books.google.com/books?id=HEBloh3nxiAC|publisher=Elsevier|location=Amsterdam, NH|date=2013|isbn=978-0-1241-5783-5}}{{cite encyclopedia|title=Drug record, Usnic acid (Usnea species)|encyclopedia=LiverTox|url=https://livertox.nlm.nih.gov//UsnicAcid.htm|date=23 June 2015|access-date=26 July 2017|publisher=National Library of Medicine, National Institutes of Health|archive-date=2 July 2019|archive-url=https://web.archive.org/web/20190702160313/https://livertox.nlm.nih.gov/UsnicAcid.htm|url-status=dead}}

Drinking kombucha can be harmful for people with preexisting ailments.{{cite journal|last1=Greenwalt|first1=C. J.|last2=Steinkraus|first2=K. H.|last3=Ledford|first3=R. A.|title=Kombucha, the Fermented Tea: Microbiology, Composition, and Claimed Health Effects|journal=Journal of Food Protection|volume=63|issue=7|year=2000|pages=976–981|issn=0362-028X|doi=10.4315/0362-028X-63.7.976|pmid=10914673|s2cid=27587313 |doi-access=free}} Due to its microbial sourcing and possible non-sterile packaging, kombucha is not recommended for people with poor immune function, women who are pregnant or nursing, or children under 4 years old:{{cite report|url=http://www.bccdc.ca/resource-gallery/Documents/Educational%20Materials/EH/FPS/Food/kombucha1.pdf|title=Food Safety Assessment of Kombucha Tea Recipe and Food Safety Plan|publisher=British Columbia (BC) Centre for Disease Control|series=Food Issue, Notes From the Field|date=27 January 2015|access-date=1 July 2015}} It may compromise immune responses or stomach acidity in these susceptible populations. There are certain drugs that one should not take with kombucha because of the small percentage of alcohol content.{{cite journal |last1=Martini |first1=Nataly |title=Potion or Poison? Kombucha |journal=Journal of Primary Health Care |date=March 2018 |volume=10 |issue=1 |pages=93–94 |doi=10.1071/HC15930 |pmid=30068458 |url=http://www.publish.csiro.au/hc/Fulltext/HC15930|doi-access=free }}

A 2019 review enumerated numerous potential health risks (including hyponatremia, lactic acidosis, toxic hepatitis, etc.{{rp|68}}), but said "kombucha is not considered harmful if about 4 oz [120 mL] per day is consumed by healthy individuals; potential risks are associated with a low pH brew leaching heavy metals from containers, excessive consumption of highly acidic kombucha, or consumption by individuals with pre-existing health conditions."

Kombucha contains a small amount of caffeine.{{Cite web|url=https://www.hollandandbarrett.com/the-health-hub/food-drink/nutrition/kombucha-benefits/|title=What is Kombucha? Benefits & Side Effects | Holland & Barrett|website=www.hollandandbarrett.com}}{{Cite web|url=https://www.bonappetit.com/story/does-kombucha-have-caffeine|title=So Does Kombucha Have Caffeine or Alcohol in It? How Much?!|date=2 July 2018|website=Bon Appétit}}

Kombucha culture, when dried, becomes a leather-like textile known as a microbial cellulose that can be molded onto forms to create seamless clothing.{{cite web|url=http://www.popsci.com/meet-woman-who-wants-growing-clothing-lab|title=Meet the Woman Who Wants to Grow Clothing in a Lab|last=Grushkin|first=Daniel|publisher=Popular Science|date=17 February 2015|access-date=18 June 2015}}{{cite web|url=http://bkaccelerator.com/biocouture-creates-kombucha-mushroom-fabric-fashion-architecture/|title=BIOCOUTURE Creates Kombucha Mushroom Fabric For Fashion & Architecture|last=Oiljala|first=Leena|date=9 September 2014|access-date=18 June 2015|publisher=Pratt Institute|url-status=dead|archive-url=https://web.archive.org/web/20150619063637/http://bkaccelerator.com/biocouture-creates-kombucha-mushroom-fabric-fashion-architecture/|archive-date=19 June 2015}} Using different broth media such as coffee, black tea, and green tea to grow the kombucha culture results in different textile colors, although the textile can also be dyed using other plant-based dyes.{{cite web|url=http://www.abc.net.au/news/2014-09-24/brewing-clothes-queensland-fashion-student-grow-garments-in-jar/5765060|title='Scary and gross': Queensland fashion students grow garments in jars with kombucha|last=Hinchliffe|first=Jessica|publisher=ABCNet.net.au|date=25 September 2014|access-date=18 June 2015}} Different growth media and dyes also change the textile's feel and texture. Dried and processed SCOBY has been investigated as a leather substitute.{{cite journal | last=Nguyen | first=Hau Trung | last2=Saha | first2=Nabanita | last3=Ngwabebhoh | first3=Fahanwi Asabuwa | last4=Zandraa | first4=Oyunchimeg | last5=Saha | first5=Tomas | last6=Saha | first6=Petr | title=Kombucha-derived bacterial cellulose from diverse wastes: a prudent leather alternative | journal=Cellulose | volume=28 | issue=14 | date=2021 | issn=0969-0239 | doi=10.1007/s10570-021-04100-5 | doi-access=free | pages=9335–9353 | url=https://publikace.k.utb.cz/bitstream/10563/1010494/3/Postprint_1010494.pdf | access-date=2025-03-27}} Additionally, the SCOBY itself can be dried and eaten as a sweet or savory snack.{{Cite web|date=17 June 2015|title=Kombucha Scoby Jerky|url=https://www.fermentingforfoodies.com/kombucha-scoby-jerky/|access-date=23 March 2021|website=Fermenting for Foodies|language=en-US}}

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• Cannabis tea, a cannabis-infused drink prepared by steeping various parts of the cannabis plant in hot or cold water
• Enviga, a carbonated green tea drink promoted with bogus health claims
• Jun, a fermented drink made from green tea and honey
• Kefir, a fermented dairy product
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• List of unproven or disproven cancer treatments
• Mushroom tea, an infusion of mushrooms in water, made by using edible/medicinal mushrooms (such as lingzhi mushroom) or psychedelic mushrooms (such as Psilocybe cubensis)
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