Kombucha tea is a drink that has been around for centuries, but has recently been gaining popularity in the US because of its purported health benefits. It is a fermented drink made with sugar, bacteria and yeast. Although it is commonly known as mushroom tea, kombuta is not a mushroom, and is rather a colony of bacteria and yeast that when combined with sugar and tea, becomes a fermented drink. The end result contains vinegar, B vitamins and other chemical components. Because it is fermented, most kombucha tea has an alcoholic content of .05 to 1.0 percent. (via Mayo Clinic)
Proponents of the fermented beverage claim that it is host to multiple health benefits, like aiding in digestion, sleep, weight loss and detoxification. It is also said to stimulate your immune system, prevent cancer, stop hair loss and improve liver function. Although many of those health benefits have been reported, there is no sound scientific evidence supporting it.
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Kombucha tea is also known to induce several adverse side effects like an upset stomach, infection and allergic reactions. What's more is that because these teas are often brewed in unsterile settings, contamination from the bacteria is likely.
The prudent option here is to hold off on drinking kombucha teas unless you enjoy the acquired taste and know that they were brewed in safe conditions until more solid scientific evidence is available.