Kombucha — Dietary supplement?


I'd like to find out about a fungus called kombucha. I've been told by some alternative health types that it is a beneficial dietary supplement when used as tea. However, I've not been able to find out anything about it. The claims, which I won't go into, seem a bit nebulous — or at least astronomical!


Dear Herbal,

Kombucha is a type of fermented tea that might taste like either sparkling cider or vinegar depending on how long it's been fermented. Popular for at least 5,000 years in China and Russia due to its believed healing and restorative properties, kombucha has recently become trendy in the United States for much of the same reasons. Purported benefits of kombucha range from immune system support and digestive stimulant to weight loss supplement and cancer-preventing food — with varying amounts of scientific evidence behind each claim. Before you sit down to your tea party and drink to good health, it's wise to be aware of the potential benefits as well as health risks involved in consuming kombucha, especially if it's been prepared incorrectly.

Kombucha is typically prepared by combining sugar with black, green, or white tea and a commercially available fungus called a kombucha mother or SCOBY (symbiotic colony of bacteria and yeast). First, the tea leaves are infused into boiled water at about 165 degrees Fahrenheit and sugar is added. After about ten minutes, the tea leaves are removed, and the SCOBY is added. The mixture is then left to ferment at room temperature for seven to ten days, covered by a cloth. The tea varieties, amount of sugar used, and varying fermentation time can affect the chemical composition and hence the health effects of kombucha. While little research has been done to assess the effects of kombucha in humans, animal and cell culture studies suggest that specific components of kombucha may provide health benefits, which include:

  • Antimicrobial activity promoted by organic acids (particularly acetic acid), large proteins, and catechins (a type of phenol)
  • Increased antioxidant activity, protected liver, and even anti-cancer effects from the presence of tea polyphenols, ascorbic acid (a form of vitamin C), and DSL (a derivative of glucaric acid)
  • Reduction of cholesterol levels and high blood pressure, related to improvement in arteriosclerosis, diabetes, and aging
  • Other benefits attributed to kombucha tea include relief of arthritis, hair re-growth, increased sex drive, acne and eyesight improvement, and even use as an underarm deodorant or soothing foot soak

Despite the increasing body of evidence, most researchers still aren't convinced of these effects. There isn't sufficient evidence to validate or refute most of these claims, especially in a clinical trial setting with human patients. Thus, the benefits remain hypotheses.

You will likely see kombucha at grocery or convenience stores all over. Its recent increase in accessibility and popularity is bolstered by increased marketing and mass production, spearheaded by major beverage companies. Though the brew can be purchased commercially, the low pH of the mixture and the presence of antimicrobial agents in the SCOBY prevent the survival of most potentially contaminating organisms, making this beverage a popular drink to brew at home. However, it’s crucial to note that if prepared incorrectly, consuming kombucha can have some risks. For example, depending on how the kombucha is brewed, there's the potential for heavy metal contamination leaching from the container. There are a number of documented cases of severe kombucha toxicity that have been linked to both overconsumption and consumption of an improperly prepared batch. Symptoms of toxicity can include dizziness, nausea, vomiting, jaundice, neck pain, and allergic reactions. If you decide to take on home-brewing, some simple rules to follow include:

  • Use clean utensils and containers — avoid ceramic pots that may leach lead.
  • Ferment for no longer than ten days, as the acidity level may become dangerously high after that.
  • Check the pH — if the acidity level is below 4.2, it's considered unsafe to consume. If the pH doesn't rise above 4.2 after a week of fermentation, the batch should be thrown away.
  • Keep a mold-free environment and check for any sign of mold growing in the batch before consumption.
  • Use the correct proportion of ingredients to prevent bad reactions and keep the kombucha spaced away from other fermenting foods to prevent cross contamination.

Even when prepared correctly, the recommended maximum daily amount is four ounces (about half a cup). It’s also good to keep in mind that sometimes the fermentation process creates some alcohol in the kombucha (usually 0.7 percent to 1.3 percent). For this reason, people who are pregnant or nursing are advised to not drink kombucha. There have also been noted health risks associated with drinking kombucha for young children and those with compromised immune systems, including individuals who live with HIV.

Probiotics found in fermented food and drinks, such as kombucha, are considered helpful for gastrointestinal function and overall health. However, there's very little evidence on the health benefits of kombucha itself. If your goal is to increase probiotic consumption, you may consider other food options such as yogurt, kimchi, sauerkraut, or sourdough bread. Ultimately, more human-related data is necessary to determine the effects of kombucha in order to establish an amount, frequency, and duration in which kombucha consumption is most beneficial. For now, it's likely safe for those without pre-existing health concerns to consume the recommended amount a day of the bubblin’ brew (especially if it's store-bought). Maybe one day research will fully explain and show that kombucha has been providing these hypothesized health benefits all along. Enjoy!

Last updated Jan 07, 2022
Originally published Apr 27, 1995

Submit a new comment


This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.

The answer you entered for the CAPTCHA was not correct.