Kombucha: What to Know Before You Sip

Nicknamed “the elixir of immortality,” this tart fermented drink is bubbling with health claims. It’s made of black or green tea, sugar, and a blob-like culture of “good” bacteria and yeast called a scoby. These live microorganisms give it its slightly acidic taste -- and a bit of natural alcohol.

People reportedly started to brew it in China more than 2,000 years ago. But it wasn’t until the late 1980s that it began to get attention in the U.S. Some people hoped it could boost the immune systems of people with HIV or AIDS -- a theory we now know to be a myth.

Some tout kombucha as a remedy that can help treat conditions from diabetes to hardening of the arteries to cancer. There are also claims that it can lower blood pressure and cholesterol and detox your body. There’s not enough evidence to back up these claims, though. Most of the health hype stems from word-of-mouth reports or animal studies. It doesn’t come from high-quality research into its effects on people.

Like other fermented products, kombucha contains tiny living organisms called microbes. Some types of microbes called probiotics boost the “good” bacteria in your gut. This boosts your immune system and helps you fight off bad bacteria. This might help you digest food and absorb nutrients, too. But it’s not clear whether the microbes in kombucha can deliver these benefits. We need more research to say for sure. 

The tea in the recipe has good-for-you antioxidants called polyphenols. They may curb inflammation in your body and lower the odds that you’ll get certain diseases. They might also might be good for gut health.

Kombucha also has B vitamins. They help your body turn food into energy, among other jobs. But you don’t have to drink fermented tea to get your B. They’re in a variety of foods. If you’re healthy, chances are you get enough already.

All kombucha has a bit of alcohol in it due to the sugar fermenting with the yeast. Commercial brands that have less than 0.5% by volume in it can be sold as “non-alcoholic.” Any more than that and the government considers it to be booze.  Fermentation time, temperature, and the way the drink is stored all play roles in how strong it becomes. Some kombucha continues to ferment even in the bottle.

Stay away from this drink if you have a weakened immune system or a long-term health condition -- especially liver, kidney, or lung disease. Don’t drink it if you’re pregnant. It’s not for young children either. But if you’re a healthy adult, the store-bought kind that’s pasteurized is fine in moderation -- but not more than 12 ounces per day. Read the nutrition label, though, because the sugar and calories can vary quite a bit by brand.

Some reports link the homemade variety to stomachaches, dizziness, nausea, infections, and allergic reactions. The risk is high when people brew it in unclean conditions. That makes it easy to taint during fermentation. Brewing or storing it in glazed ceramic pots has a link to lead poisoning, too.

It’s important to always keep kombucha in the refrigerator, even before you drink it. If you leave a capped bottle at room temperature for a while, the carbonation in it could build up -- and you might get a surprise splash when you open the bottle. The cold of the fridge also slows the fermentation.