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Dear Doctor: Kombucha tea

I've been hearing a lot recently about the health benefits of Kombucha tea. Is it a good idea to take it?

Is Kombucha tea good for you? Someone recommended taking it, but I don’t know anything about this type of tea.

Kombucha tea, also known as Manchurian or Kargasok tea, has been popular for a long time in other countries, and is now gaining popularity in Europe.

It is frequently referred to as a mushroom, which it looks like, but it's a colony of bacteria and yeast, commonly called SCOBY (symbiotic colony of bacteria and yeast).

Kombucha tea is made by adding the colony to sugar and black or green tea and allowing the mix to ferment for a few weeks. The liquid contains vinegar, B vitamins and a number of other chemical compounds. The fermentation process is said to produce gluconic acid, hyaluronic acid and other compounds.

It claims to have many types of health benefits, such as stimulating the immune system, improving digestion, eliminating toxins, improving eyesight, treating skin conditions and arthritis and even preventing cancer, but none of these benefits have been proven. This doesn't mean that Kombucha tea can't have any benefits for your health; it just means that there is no direct evidence that it provides the benefits it claims to have.

Does it contain anything that could make you unwell?

Different Kombucha teas may contain moulds and fungi, some of which can cause illness. After the tea is fermented, it is highly acidic and contains alcohol and other compounds. In order to maintain its possible health benefits, Kombucha tea is left unpasteurised or raw. One of the concerns with raw Kombucha is that it may continue to ferment and carry harmful bacteria as a result, unless it is refrigerated.

There have been several reports that Kombucha tea can cause stomach upsets and allergic reactions. More toxic reactions include metabolic acidosis -- an abnormal increase of acid levels in body fluids, as well as yellowing of the skin from liver damage. Deaths have been linked with the tea.

There is a high risk of contamination because Kombucha tea is often brewed in homes under non-sterile conditions. Lead poisoning is a risk if ceramic, lead crystal, or painted pots are used for brewing -- the acids in the tea may leach lead from its container.

Should someone recovering from cancer take it?

In short, no. Kombucha tea is promoted as a cure-all for a wide variety of conditions, including cancer, Aids and MS. This is because it is said to contain antioxidants, compounds that block the action of free radicals (activated oxygen molecules that can damage cells). For people with cancer, it is tempting to take something that claims to improve the body's defenses. But until more definitive evidence is available, it's best to avoid it.