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    Brent A. Bauer, M.D.

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Question

Kombucha tea: What are the health benefits?

What is Kombucha tea? What are the health benefits of Kombucha tea?

Answer

from Brent A. Bauer, M.D.

Long popular in other countries, Kombucha tea is gaining popularity in the United States. Although frequently referred to as a mushroom, which it resembles, Kombucha is not a mushroom — it's a 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. The resulting liquid contains vinegar, B vitamins and a number of other chemical compounds. Kombucha tea is commonly prepared by taking a starter sample from an existing culture and growing a new colony in a fresh jar. Health benefits attributed to Kombucha tea include stimulating the immune system, preventing cancer, and improving digestion and liver function.

As with any dietary supplement, it's critical to do your homework before considering using Kombucha tea. First, determine the level of evidence supporting the health claims. In this case, Kombucha tea's benefits are based on personal reports, and lab and animal studies. To date, there hasn't been a single human trial reported in a major medical journal. This doesn't mean that Kombucha tea can't possibly have health benefits; it just means that at this time there's no direct evidence that it provides the benefits it's reported to have.

The next question is whether there have been any reports of harm or illness caused by the product. In the case of Kombucha tea, there are reports of adverse effects such as stomach upset and allergic reactions. More worrying are the reports of toxic reactions and metabolic acidosis. In addition, the Food and Drug Administration cautions that the risk of contamination is high because Kombucha tea is often brewed in homes under nonsterile conditions. Lead poisoning also may be a risk if ceramic pots are used for brewing — the acids in the tea may leach lead from the ceramic glaze.

In short, there's not good evidence that Kombucha tea delivers on its health claims. At the same time, several cases of harm have been reported. Therefore, until definitive studies quantify the risks and benefits of Kombucha tea, it's prudent to avoid it.

Next question
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References
  1. Greenwalt CJ, et al. Kombucha, the fermented tea: Microbiology, composition, and claimed health effects. Journal of Food Protection. 2000;63:976.
  2. FDA cautions consumers on Kombucha mushroom tea. U.S. Food and Drug Administration. http://www.fda.gov/bbs/topics/ANSWERS/ANS00650.html. Accessed May 7, 2009.

AN01658

June 26, 2009

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