June 2015 Issue

For Your Information: The Wonders of Kombucha Tea — Is it Healthful or Hazardous?
By Beth W. Orenstein
Today's Dietitian
Vol. 17 No. 6 P. 20

Some people like to make their own bread or yogurt, while others like to brew their own kombucha tea. Kombucha (pronounced kom-boo-cha) tea is a fermented beverage made with tea, sugar, bacteria, and yeast. While the scientific evidence is scant, people around the world have drunk the concoction for centuries believing it has health benefits, including improving digestion and preventing cancer and the effects of aging.

Nutrition consultant Jennifer McDaniel, MS, RDN, CSSD, LD, a spokesperson for the Academy of Nutrition and Dietetics, based in St. Louis, likes to drink kombucha tea for two reasons: She likes its quirky, slightly sweet yet vinegary taste, and, more importantly, kombucha tea is part of her plan to get more fermented foods in her diet. Fermented foods, she says, contain gut-friendly bacteria or probiotics that aid in digestion and boost one's immune system. "I'm always looking for ways to sprinkle in good bacteria in my body," she says. "I eat sauerkraut and blue cheese. I drink kefir milk. And kombucha tea is one more."

Other dietitians and researchers, however, are skeptical about the health benefits of kombucha tea and haven't seen enough scientific evidence to recommend it. "There's a lot of promise with this tea," says Maria L. Marco, PhD, an associate professor in the department of food science and technology at the University of California, Davis. "But there just aren't enough clinical studies to assess how true the claims of its health benefits are."

Ancient Origins
Kombucha is said to have originated in Asia during the Chinese Tsin dynasty in 212 BC. It's believed that kombucha gets its name from a Korean physician named Kombu, who introduced the tea to Japan around 415 AD. Over the centuries, traders and travelers brought the Eastern tea to India and Russia. A Japanese visitor to Russia believed kombucha tea was responsible for the good health and longevity of the people he found living in Kargasok on the left bank of the Ob River.

The fermented "miracle" tea was widely popular throughout Europe until World War II caused shortages of the tea and sugar needed to make it. In the early 1990s in America, kombucha tea was a popular product found mostly in health food stores and hippies' kitchens. Today, it's become popular again. Starter cultures for home brewing are available online. It costs about $1 per gallon to make your own kombucha tea. Commercially bottled teas (usually 16 oz) are sold in mainstream grocery stores such as Whole Foods for about $6 each or more and in discount stores including Walmart for about $4 each.

How to Make It
The tea is fairly simple to make, McDaniel says. You need a mother culture, or symbiotic colony of bacteria and yeast (SCOBY). The rubbery disc SCOBY looks like a mushroom, which is why some people refer to kombucha as kombucha mushroom tea. You can buy a starter kit online, such as from Amazon.com, or get a SCOBY from a friend who makes kombucha tea.

The process involves brewing green or black tea and adding sugar. After it cools, you add the SCOBY plus a little kombucha tea from a previous batch and let the mixture ferment in a glass jar.

The tea takes about seven to 14 days to ferment. The warmer the house temperature, the faster it will ferment. McDaniel says she prefers to make her tea in the summer when the house is warmer, and it's more refreshing to drink. "You can make it in the winter," she says, "but it may take a couple of extra days."

When making kombucha, you must use real sugar; otherwise it won't ferment, McDaniel says. Thanks to the sugar, a glass of the tea has about 60 kcal, about one-half that of a similar amount of soda. You can use decaffeinated tea (green or black) but then you won't get the caffeine boost, McDaniel notes. The caffeine in the tea could be what gives its drinkers an energy boost, she says.

The longer you let the kombucha ferment, the more acidic it tastes. "Finding your preferred flavor takes some fine tuning," McDaniel says, adding that you could do a taste test by pouring out a little at day seven to see if you like it. Too sweet? Let it ferment a bit longer. Because of the fermentation process, the tea is slightly fizzy. 

Commercial Preparations
Sold in the refrigerated section of grocery and health food stores, no one brand of kombucha tea tastes exactly the same as another. "They can vary slightly in their profile," McDaniel says. Finding one you like is a matter of personal preference just as home brewing is. Some leading brands are GT, Yogi, and Celestial Seasonings. Many commercial kombucha drinks have flavorings added that reduce its vinegary taste.

Diana Cullum-Dugan, RDN, LDN, RYT, of Watertown, Massachusetts, says some people like the slightly sour vinegary taste of kombucha. She isn't one of them. "I think people train themselves to be OK with certain tastes," she says. "I have people who swear by it and say that it tastes so good, but not me. The last kombucha tea I tasted was what I made, and I'm just not interested."

Health Risks
Some health experts, including those at Mayo Clinic, warn home brewers to be careful. "You run the risk of having bacteria and mold growing in a bowl if you leave it too long," Cullum-Dugan says.

The Centers for Disease Control and Prevention (CDC) recommends that people limit their consumption of kombucha tea to 4 oz per day. The CDC's recommendation is in response to two older people who became ill when drinking 12 oz per day of very acidic kombucha, according to a report published in November 2013 in the Journal of Environmental Health.1 "As long as the tea is made by a reputable company, there's really no harm in drinking it," Marco says. However, people who are immune compromised or elderly would be wise to avoid this type of drink because it contains high numbers of bacteria, she says. Some people reportedly have died from home brewed kombucha and kombucha tealike products.2

To safely brew kombucha at home, throw out the SCOBY if it begins to grow mold. Also, sanitize brewing containers between batches, and store kombucha away from direct sunlight. 

Health Benefits
What scientific research there is on kombucha isn't very rigorous. "At this point, it's been studied but to a very limited extent," Marco says. "There are studies, but they're generally performed in a laboratory and not in people." Cullum-Dugan says she's seen nothing in the literature to support claims of better digestion or improved liver or pancreatic function from drinking kombucha tea. The reports of people drinking the tea and feeling better are largely anecdotal, she says. One study published in the February 2014 issue of the Journal of Medicinal Food found that kombucha tea has detoxifying properties, protects against free radical damage, has energizing capabilities, and promotes immunity.3 The researchers, who analyzed recent animal studies, concluded that kombucha tea has potential preventive and curative effects on a number of metabolic and infectious diseases.

If someone were to ask Cullum-Dugan's advice as a dietitian whether to add kombucha tea to a diet, she'd say no. "I'd refer clients to other places," she says. "If they're looking for a probiotic in their diet, I'd recommend certain yogurts, kefir, and fermented vegetables such as kimchi instead of kombucha. There's more research on those foods, and they're cheaper."

Marco says more research is definitely needed to help settle the debate. "The problem with kombucha and other fermented foods is that it's hard to get a good clinical study funded. Kombucha is mostly relegated to alternative medicine or folklore, but it's certainly an area we should be studying. We should be funding such studies to see if it can offer sustainable health benefits."

— Beth W. Orenstein is a freelance writer in Northampton, Pennsylvania, and a regular contributor to Today's Dietitian.

1. Nummer BA. Kombucha brewing under the Food and Drug Administration model Food Code: risk analysis and processing guidance. J Environ Health. 2013;76(4):8-11.

2. Unexplained severe illness possibly associated with consumption of kombucha tea — Iowa 1995. Centers for Disease Control and Prevention website. http://www.cdc.gov/mmwr/preview/mmwrhtml/00039742.htm

3. Vīna I, Semjonovs P, Linde R, Deniņa I. Current evidence on physiological activity and expected health effects of kombucha fermented beverage. J Med Food. 2014;17(2):179-188.