Researchers at Aberystwyth University in Wales have found that daily kombucha consumption alters health-related chemical compounds in healthy adults but does not affect stress levels.
The eight-week clinical trial monitored 40 healthy adult volunteers to evaluate the physiological impacts of drinking the fermented beverage on a regular basis.
Participants were randomly split into two groups under a double-blind protocol, a clinical research standard designed to prevent bias by withholding treatment details from both subjects and researchers. One group consumed a measured daily dose of kombucha, while the control group received a placebo consisting of flavoured water.
Laboratory analysis of blood and urine samples taken at the start and conclusion of the trial revealed measurable shifts in specific compounds associated with health benefits. However, kombucha consumption produced no noticeble differences in standardized tests measuring physiological stress response, which had been one of the primary targets of the investigation.
Clinical testing and beverage composition
Kombucha is prepared by fermenting sweetened tea with a symbiotic culture of bacteria and yeast, commonly referred to by the acronym SCOBY. Originating centuries ago in regions of East Asia, the drink has experienced rapid commercial growth across Western markets, including Europe and North America.
The researchers highlighted that commercially available kombucha lacks a uniform chemical profile. Variations in fermentation time, ambient temperature, and specific microbial colonies alter the concentration of organic acids, vitamins, and minerals from batch to batch, presenting a challenge for standardized scientific testing.
The research initiative received funding support from Innovate UK, the national innovation body responsible for driving research and development across the United Kingdom, and was conducted alongside a commercial Welsh kombucha manufacturer. Beyond evaluating human health markers, the study examined how specific chemical compounds evolve during brewing and subsequent storage.
Evidence from human trials
Scientific evidence examining kombucha directly in human subjects remains relatively scarce compared to cell or animal studies. Emma Short, a specialist in gastrointestinal pathology, told the BBC that fewer than ten human trials investigating kombucha had been published prior to 2025, noting that most previous data relied on laboratory experiments.
Amanda Lloyd, one of the lead investigators on the trial, stated that although the findings expand human data on kombucha, they do not validate all popular health claims surrounding the drink. Lloyd added that kombucha cannot replace a varied and balanced diet.
