According to the results of a systematic review, there is a lack of evidence supporting the potential health benefits of kombucha, a fermented tea beverage, in humans.

While known worldwide for thousands of years, kombucha, made by fermenting tea and sugar with Symbiotic Culture of Bacteria and Yeast (SCOBY), has only recently become popular in the United States. Its popularity is likely due to its supposed health benefits, some of which include: antiinflammatory and antioxidant activity; reductions in cholesterol levels, blood pressure, and cancer propagation; and improvements in hepatic, immune system, and gastrointestinal function.

To investigate these claims, the authors conducted a systematic review identifying literature discussing the empirical health benefits of kombucha in humans and to determine future research opportunities. They searched PubMed, Scopus, Ovid, the National Institutes of Health Research Portfolio Online Reporting Tools, clinicaltrials.gov, and clinicaltrialsregister.eu to obtain studies discussing kombucha in human subjects.

A total of 310 articles were reviewed. “Our systematic literature review found no articles on the empirical health benefits of kombucha as identified from human subjects research,” the authors explained, “One study was identified through the references of a microbiology study.”

Regarding the potential health risks of kombucha, case reports of hyponatremia, lactic acidosis, toxic hepatitis, and even cutaneous anthrax (from topical application of kombucha mushroom to the skin for analgesia) were identified; small amounts of alcohol were also detected in a Food and Drug Administration investigation. Generally, the authors noted that healthy individuals could consume 4oz of kombucha per day without harm, however those with pre-existing conditions (renal or hepatic impairment, pulmonary conditions) are more likely to be at risk for adverse events.

In their review, the study authors also suggested several research opportunities scientists should consider to further increase knowledge surrounding the effects of kombucha in humans. These include assessing the relationship between trends in food consumption with population health outcomes, performing cross-sectional and cohort studies analyzing health-related outcomes associated with kombucha use, as well as conducting clinical trials in human subjects.

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“Significant commercial shelf space is now dedicated to kombucha products, and there is widespread belief that the products promote health,” the authors stated. “It is critical that these assertions are tested in human clinical trials.”

For more information visit sciencedirect.com.

This article originally appeared on MPR