They’re popping up in trendy neighborhoods. And while they may be a sign that a neighborhood has culture, we’re not talking about museums and art galleries. We’re talking about bars that serve something different on tap!
Instead of pouring alcoholic beverages, these bars are serving up varieties of kombucha, a fermented beverage that does actually contain a small amount of alcohol but, more important, is purported to grant a number of health benefits.
Related Article: The Importance of Fermented Foods
Health Fad or Real Benefits?
While erroneously believed by some people to be a type of mushroom, kombucha is actually black or green tea fermented with a culture of bacteria and yeast. It is a source of probiotics, which are beneficial bacteria. The beverage originated in Manchuria over 2,000 years ago and was later exported to Japan. It has been popular in Russia and Germany and began appearing in the U.S. two decades ago. The mildly effervescent beverage is frequently consumed sweetened, but its acidic taste is savored by aficionados.
“Although the beneficial and/or adverse effects of kombucha tea on human health have not been scientifically determined yet, there are several reasons to believe that kombucha may have desirable positive effects on human health,” note Ahmed Aloulou and colleagues in BMC Complementary and Alternative Medicine. The authors point out that several recent studies demonstrate that kombucha can reduce cell damage caused by oxidative stress. They further note that kombucha is reported to improve resistance against cancer, prevent cardiovascular diseases, promote healthy digestion, stimulate the immune system, and reduce problems related to inflammation.1
Kombucha’s main biological functions have been identified as glucuronic acid production, antibacterial activity, and antioxidant activity.2
In rats that received a lead acetate solution daily (which induces oxidative stress), kombucha lowered lipid peroxidation and DNA damage while increasing the levels of reduced glutathione and glutathione peroxidase, the latter being one of the body’s antioxidant enzymes.3 It also alleviated lead-induced immunosuppression.
In another rat study, oral administration of kombucha offered protection against the effects of stress induced by exposure to cold and low oxygen conditions, indicated by the prevention of a decline in reduced glutathione and lipid peroxidation, and helped protect the liver against acetaminophen-induced toxicity.4
In a mouse model of stomach ulceration induced by the drug indomethacin, kombucha demonstrated the best healing effects in comparison with black tea or tea fermented with Candida parapsilosis. Kombucha’s superior effects were attributed to its antioxidant activity and its protective effect on gastric mucin content.5 The authors note that the kombucha tea used in this study was as effective at healing ulcers as the proton pump inhibitor omeprazole.
In rats in which diabetes was induced by administration of the compound alloxan, kombucha extract given for 14 days was more effective than unfermented black tea at reversing some of the adverse changes induced by alloxan, including those observed in pancreatic tissue.6 Another study involving alloxan-treated diabetic rats given kombucha or an unfermented tea found that kombucha was better than black tea at suppressing elevated blood glucose. It was discovered that kombucha lowered the activity of alpha-amylase, a pancreatic enzyme that plays a role in the digestion of carbohydrates, and pancreatic lipase, which breaks down dietary fats. Kombucha was also associated with an increase in high-density lipoprotein (HDL) cholesterol, protection of kidney and liver function, and other positive effects, leading the researchers to conclude that kombucha tea can be considered a strong candidate as a potential functional supplement to treat and prevent diabetes.1
A study of rats that underwent myocardial infarction subsequent to injection of the drug isoproterenol revealed a protective effect for pretreatment with kombucha against increases in heart weight, blood glucose, and albumin, accompanied by decreases in total, low-density lipoprotein (LDL), and very-low-density lipoprotein (VLDL) cholesterol; triglycerides; and leakage of cardiac markers from the heart muscle.7
Among rats fed high cholesterol diets that received kombucha or green tea for 16 weeks, kombucha more effectively raised HDL cholesterol and lowered triglycerides and serum total, LDL, and VLDL cholesterol.8 Kombucha was also associated with a lower marker of lipid peroxidation in the liver and kidney compared to animals that received a high cholesterol diet alone. The authors suggest that kombucha tea be evaluated in humans.
In mice, three years of consuming kombucha was associated with greater exploration and object manipulation, as well as longer life, in comparison with animals that were not given the beverage.9
An ethyl acetate fraction of kombucha tea injected into the skin of aged mice significantly increased collagen and NAD+/NADH levels.10 Kombucha improved connective tissue abnormalities associated with aging without inducing sensitivity or irritation.
One study found a protective effect for kombucha tea against carbon tetrachloride–induced liver toxicity that was greater than that of black tea.11 Subsequent research identified a compound produced by a specific bacterial strain in kombucha that may be responsible for its liver-protective effect.12
Research has also revealed the presence of isorhamnetin, an antibacterial flavonoid in kombucha that is not present in unfermented tea.13 The study is the first to identify the flavonoid in kombucha and concludes that kombucha can be used against enteropathogenic bacterial infections due to its polyphenolic content.
A concern has been raised regarding the safety of the beverage, which is often fermented by home cultivators for a week or more at room temperature. An examination of kombucha for contamination led researchers at Germany’s Justus Liebig University to the conclusion that kombucha is safe; however, it is suggested that immunosuppressed individuals consume commercial kombucha beverages whose production is regulated.14 Kombucha has been shown to have an antibacterial effect against Staphylococcus aureus, Shigella sonnei, Escherichia coli, Aeromonas hydrophila, Yersinia enterocolitica, Pseudomonas aeruginosa, Enterobacter cloacae, Staphylococcus epidermidis, Campylobacter jejuni, Salmonella typhimurium, Salmonella enterica serotypeEnteritidis, Bacillus cereus, Helicobacter pylori, and Listeria monocytogenes.15 Studies in rats given kombucha tea for 90 days found no toxic effects.16
“The recent experimental studies on the consumption of kombucha tea suggest that it is suitable for prevention against broad-spectrum metabolic and infective disorders,” Ilmāra Vīna and colleagues conclude in a 2014 review17. “This makes kombucha tea attractive as a fermented functional beverage for health prophylaxis.”
The Bottom Line
While more human studies are needed to substantiate the benefits of kombucha, its rich supply of probiotics may be the top reason to drink it. Research has shown the species Lactobacillus is prominent.18 Interestingly, NASA is researching the efficacy of probiotics in foods for astronauts, and kombucha may be a viable option. International researchers state that “the astronaut’s diet is not rich enough in vegetables (soluble and insoluble fibers), and taking probiotics may not be so effective” because of insufficient food sources for the probiotic bacteria. Since probiotic bacteria require prebiotics as a food source for the bacteria to thrive, “kombucha tea … may be a promising formulation of a probiotic/prebiotic for extreme expeditions.” The authors also highlight that kombucha provides a source of both probiotic bacteria and yeast, as well as prebiotics (microcellulose), which help fuel the growth of helpful microorganisms in the gut.19
- Aloulou A et al. BMC Complement Altern Med. 2012 May 16;12:63.
- Nguygen NK et al. Springerplus. 2015 Feb 24;4:91.
- Dipti P et al. Biomed Environ Sci. 2003 Sep;16(3):276-82.
- Pauline T et al. Biomed Environ Sci. 2001 Sep;14(3):207-13.
- Banerjee D et al. Food Funct. 2010 Dec;1(3):284-93.
- Bhattacharya S et al. Food Chem Toxicol. 2013 Oct;60:328-40.
- Lobo RO et al. J Food Sci Technol. 2015 Jul;52(7):4491-8.
- Bellassoued K et al. Pharm Biol. 2015;53(11):1699-709.
- Hartmann AM et al. Nutrition. 2000 Sep;16(9):755-61.
- Pakravan N et al. J Cosmet Dermatol. 2017 Nov 19.
- Murugesan GS et al. J Microbiol Biotechnol. 2009 Apr;19(4):397-402.
- Wang Y et al. J Sci Food Agric. 2014 Jan 30;94(2):265-72.
- Bhattacharya D et al. Curr Microbiol. 2016 Dec;73(6):885-896.
- Mayser P et al. Mycoses. 1995 Jul-Aug;38(7-8):289-95.
- Sreeramulu G et al. J Agric Food Chem. 2000 Jun;48(6):2589-94.
- Vijayaraghavan R et al. Biomed Environ Sci. 2000 Dec;13(4):293-9.
- Vīna I et al. J Med Food. 2014 Feb;17(2):179-88.
- Marsh AJ et al. Food Microbiol. 2014 Apr;38:171-8.
- Kozyrovska et al. Biopolymers and Cell. 2012 January; 28(2):103-113.