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What is Kombucha?

In Japanese, kombucha means “seaweed tea”; it is a “tea” made out of the seaweed called kombu. The Japanese consider it to be very healthy. However, this is not the same kombucha tea that Westerners drink.

Kombucha is an unusual-tasting drink. Depending on what’s added to it, it’s best described as a sour apple cider, perhaps with vinegary notes.

Initially drunk in China more than 2,200 years ago for its detoxifying and energizing characteristics, this venerable beverage found its way to Russia and from there into other eastern European areas via trade route expansion. It became popular in Germany during WWII, and further demand for the drink increased in the 1950s in North Africa and France. As early as the 1960s Swiss scientists claimed kombucha was helpful for maintaining digestive health, much like yogurt.

How to make a Kombucha SCOBY

A green or a black tea base is used to make kombucha, then white sugar is added which has been fermented with a type of “tea fungus” called a symbiotic culture of acetic acid (vinegar) bacteria and yeast, or SCOBY, for one to two weeks. The taste of the kombucha changes during the fermentation process from a pleasingly fruity sour-like effervescent flavor, to a mild vinegary taste after a long gestation period.

The fermentation process is critical as the SCOBY changes the polyphenols –- compounds normally found in tea, fruits and vegetables –- into other natural compounds. This increases the acidity, which prevents other microorganisms from multiplying. These newly-created organic compounds are claimed to provide health benefits beyond those already found in green or black tea.

The development of fermentation

The fermentation process prolongs the serviceable life of kombucha, as it does with other classically popular foods and drinks such as cheese, yogurt, sauerkraut, kimchi, wine and beer. Although beer and wine become alcoholic during the fermentation process, kombucha usually consists of less than 0.5% alcohol, so is classified essentially as non-alcoholic. Ethanol develops when the yeasts and bacteria in the SCOBY interact via a process called glycolysis. The acetic acid bacteria in the SCOBY utilizes the ethanol to produce vinegar (acetic acid), which is partially responsible for its sour taste.

Gastrointestinal health

Lightly fermented foods contain healthy bacteria. There is a theory that these bacteria help settle our gastrointestinal system, which early research suggests may enhance a range of bodily functions from our mood and stress levels, to our weight and cravings for food. But merely consuming healthy bacteria won’t automatically generate these bacteria to permanently live in, or colonize, the gut. To achieve any longstanding health advantages from foods containing live bacteria, known as probiotics, the current research advocates taking them constantly.

Although the impact on other diseases like inflammatory bowel disease is uncertain, there is evidence that probiotics can be advantageous in some groups of people, such as those who suffer from certain gut problems like C. difficile infection. However, it is still unknown whether probiotics, whether in the form of kombucha or yogurt, are beneficial to the wider population. To cultivate good gastrointestinal health, it is best to eat a wide variety of nutritious foods.

Kombucha’s other health applications

There are many impressive health claims about kombucha, including detoxification of the blood, reduction of cholesterol levels, reduction of blood pressure, diabetes care, antibacterial effects, and anti-ageing abilities. There have been several “lab bench” studies looking at isolated cells and researching kombucha’s effects on animals. This provides us with insufficient evidence, as human biological systems frequently work differently. Currently there are no published studies from human clinical trials of drinking kombucha. Two reviews of the lab bench and animal studies on kombucha in 2000 and 2014 indicate the drink may have antimicrobial, antioxidant, anti-cancer and anti-diabetic properties. The studies also indicate some provocative procedures by which kombucha could conceivably be used to heal gastric ulcers and high cholesterol, and promote the body’s immune response and liver detoxification. But they do not yet tell us if they transmute to humans.

A chemical called DSL (D-Saccharic acid-1,4-lactone) is potentially the most beneficial component in kombucha. DSL has the capability to suppress an important enzyme, β-glucuronidase, which may be linked to cancer growth. But again, this has not been demonstrated in humans.

Lab-bench studies have nevertheless detected the existence of polyphenols, acids and vitamins that are also found in traditional green and black tea.


The health properties of kombucha are presumed to be similar to drinking tea or other fermented foods. If you enjoy kombucha, continue drinking it, but if you prefer the traditional black and green tea, there are excellent health reasons to continue drinking those. While some intriguing properties have been shown from lab bench and animal studies, it doesn’t necessarily follow that we will see these same benefits in humans.

Remember that some of the kombuchas on the market have fruit juice added after the fermentation process, which will augment overall sugar intake. The amount of sugar in these varieties can range from 10-15g per serving (two to three teaspoons), so if you have regular tea without sugar, drinking kombucha will increase your sugar intake.