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Another hope for good health that's becoming more and more popular is kombucha, which is a fermented brew of sweetened tea and bacteria. Consumers are hoping the drink will help them fight off disease, improve energy and even inhibit aging.
NPR's Patti Neighmond looks at what we do and do not know about kombucha.
PATTI NEIGHMOND, BYLINE: The bottles are artsy and colorful, the flavors varied; citrus, watermelon, ginger. And the taste, well, acquired.
BRIAN SMITH: For me it's sort of like a vinegar soda, in a way. Like it has like an effervescence to it.
NEIGHMOND: Brian Smith gets his kombucha tea at a local grocery store in Washington, D.C., So does Erin Upton-Cosulich.
ERIN UPTON-COSULICH: The taste is a little bit like beer, kind of tangy and a little bit sweet.
NEIGHMOND: Kombucha is a mixture of black or green tea, sugar, yeast and bacteria. And consumers like Annie Sprengelmeyer say it just makes them feel better.
ANNIE SPRENGELMEYER: It gives you a little bit of a different kind mind clearing. For me it just kind of wakes me up.
NEIGHMOND: Lots of kombucha drinkers describe a similar energy boost or sense of well-being, but bottom line, we just don't know very much about kombucha. And some of the benefits touted, says nutritionist Monica Reinagel, go way too far.
MONICA REINAGEL: I've seen claims that kombucha will help cure cancer, that it's a powerful detoxifier, that it's the fountain of youth.
NEIGHMOND: Pretty hefty claims and pretty unlikely, says registered dietitian Andrea Giancoli, spokesperson for the Academy of Nutrition and Dietetics.
ANDREA GIANCOLI: There is really very little evidence to support any kind of claims of kombucha tea. We don't know if it does anything at all.
NEIGHMOND: But because most kombucha drinks contains live bacteria, there could be certain health benefits. Evidence is mounting that friendly bacteria or probiotics aid in digestion and possibly even strengthen the immune system.
Nutritionist Monica Reinagel.
REINAGEL: They actually live inside of us and they help digest our food. They actually produce certain nutrients for us, which is a very nice trick.
NEIGHMOND: In the early '90s, kombucha was made in home kitchens. First, black or green tea was sweetened with sugar, then a concoction of bacteria and yeast added. The mixture was fermented for at least a week to speed up production of the bacteria, which took the form of a rubbery layer of goop on top of the tea.
REINAGEL: If you've ever left a cup of coffee on the kitchen counter and gone away for vacation, and come back later and found a little layer of mold on the top of your coffee, that's kind of what it looks like.
NEIGHMOND: That goop is actually a thriving colony of bacteria - billions of them, so it's really difficult to know whether they include the desired friendly bacteria or not.
One of the most popular brands of kombucha tea, GT's Kombucha, sells millions of bottles a year. Officials say they test their tea and know it contains at least two important strains of good bacteria.
But that may not be the case for all products now available. And if you brew it at home, dietitian Giancoli has a warning.
GIANCOLI: You've got to really have very sanitary conditions and know what you're doing.
NEIGHMOND: If you don't, your tea could get contaminated by not so friendly harmful bacteria.
In stores, the bottled versions are produced in carefully controlled environments. So if it makes you feel better, nutritionist Reinagel says there's probably no harm in drinking it.
Patti Neighmond, NPR News.
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