Kombucha: Benefits and risks

Kombucha is a type of fermented beverage consumed worldwide. It is made traditionally by fermenting a mixture of water, sugar, black tea, and SCOBY (a “symbiotic culture of bacteria and yeast”). The final product is a tea that can contain vitamins, minerals, yeast, bacteria, acids, and alcohol. Flavored kombuchas have added fruits, vegetables, juices, purees, spices, other teas, coffees, or herbs.

Little evidence exists as to the benefits and safety of kombucha.
Four (4) ounces a day of the beverage isn’t likely harmful,
but more might cause unwanted side effects.

Are there known benefits from kombucha?

Kombucha is often marketed to boost immunity, increase energy, improve gastrointestinal (GI) function, prevent cancer, improve joint health, lower blood pressure/cholesterol, improve liver function, and act as an antioxidant. Few to no scientific research studies have been performed with humans to explore the previously mentioned claims.

One reason offered for the benefits of kombucha relates to the probiotic bacteria with which it is made and which it creates. Probiotics are live bacteria and yeasts that can help the human body digest food, produce vitamins, or destroy disease-causing cells. Many are the same or similar to probiotics your body makes naturally. Much research has been done on probiotics over the years, but still little reliable evidence supports the benefits of probiotics in foods and supplements.

How is kombucha sold?

Kombucha in liquid form usually is sold as a conventional food and carries a Nutrition Facts label. However, kombucha also can be purchased as a dietary supplement in the form of a capsule, powder, or liquid. In this case, the product should have a Supplement Facts label, as required for dietary supplements.

There are very few kombucha supplements on the market. Some of these products only contain ingredients typically found in kombucha, such as B vitamins, probiotics, and green or black tea. Other products reportedly contain just the dried or liquid extracts of the kombucha culture. They claim to have the same health benefits as the beverage. For more information, see the Operation Supplement Safety (OPSS) Quick Facts about kombucha.

Kombucha is also sold as an alcoholic beverage. Kombucha naturally contains a small amount of alcohol as a result of the fermentation process. Similar to fruit juices, soft drinks, and other flavored beverages, kombucha  must have less than 0.5% alcohol by volume. However, some contain more, so it’s important to check the label to make sure you aren’t buying something with more alcohol than you want.

What risks are associated with kombucha?

If brewed incorrectly, kombucha can put you at risk for side effects such as stomach problems, nausea, vomiting, head or neck pain, lactic acid buildup in the bloodstream, hepatitis, and lead poisoning. The FDA has a set of guidelines that manufacturers must follow to prevent kombucha from becoming harmful, but this isn’t always followed for home-brewed kombucha.

To reduce the chance of drinking a harmful batch, it’s best to buy kombucha from a reliable source. Generally, these sources sell their products refrigerated, in glass containers, with proper labeling. The label should have an ingredients list including any additives, the name and address of the manufacturer or distributor, the amount in the container, the words “keep refrigerated,” and be free of questionable claims or statements.

Most kombucha is refrigerated to slow down fermentation after it is bottled. If fermentation continues, this could cause the container explode or break (carbon dioxide will buildup and cause pressure), the alcohol content could increase (turning it into an alcoholic beverage), or the pH could decrease (becoming too acidic to drink). Because kombucha is acidic, glass is used to reduce the chance that the acid will “pull out” chemicals (such as lead) from the container.

If you brew kombucha at home, be sure your SCOBY doesn’t show signs of green, white, black, or grey cultures, which could be a sign of mold. Also, the amount of sugar in kombucha can vary from bottle to bottle, especially with flavored kombucha. Choose kombucha with a low sugar content (less than 6 grams of sugar per 12 ounces and no added sugars).

The Centers for Disease Control (CDC) reports that about 4 ounces per day is not considered to be harmful. However, there are possible risks in drinking too much, especially for those with health problems. It is important to keep in mind that kombucha serving sizes often vary, ranging anywhere from 8–20 ounces. Given the potential dangers, pregnant women (due to alcohol content) and those with chronic conditions should avoid drinking kombucha until more reliable information is available about its effects.

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