Forget low-carb, high-fat ketogenic diets, gluten-free foods and all things detox. These are diet bygones compared to a slightly-sparkling, gold-coloured fermented drink called kombucha that is now all the rage. They say Madonna drinks it, so does Halle Berry, Lindsay Lohan and Gwyneth Paltrow. Even testosterone-fuelled Jake Gyllenhaal and Orlando Bloom were seen clutching a bottle.
In Thailand, kombucha has taken the town by storm. Online communities have been set up and started mushrooming to exchange ideas and even "scoby" -- slimy, rubbery kombucha starter culture -- among brewers. Kombucha even made its way into the country's gastronomic circle where chefs and mixologists incorporated the beverage into their menus served at many fine-dining eateries. New York Times predicted kombucha as one of the food trends of 2019 and that the fermented tea will show up in unexpected places like salad dressings. At times, kombucha is a show star in beauty merchandise.
Many people brew and drink kombucha for its claimed medical benefits -- from improving gut health and reducing risks of heart disease to providing antioxidants, keeping diabetes at bay, helping with weight loss and even shielding against cancer. But nutrition expert Chalat Santivarangkna suggested that consumers should not yet buy these claims unless there are medical studies to back them up.
"Kombucha brewing can make a good hobby. It can create a community. It can be fun. But do not expect it to be a cure-all drink," said Chalat, lecturer and head of the Centre of Innovation and Reference on Food for Nutrition under Mahidol University's Institute of Nutrition.
Believed to have originated in China before making its way to Japan, Russia, Eastern Europe and America, kombucha has a theory behind its name. The name kombucha has been said to have come from a Korean doctor Kombu who treated Emperor Inyko of Japan with the drink, which means it has nothing to do with kombu seaweed which many people believe.
In a nutshell, kombucha is a fermented tea. The original recipe is made by boiling black tea with sugar before leaving it to ferment. The fermentation could take two days up to two weeks. The end product is strained before consumption.
During the fermentation process, bacteria and yeast in the liquid convert the sugar into ethanol and acetic acid, giving kombucha its distinctive sour taste. During fermentation, scoby -- which stands for symbiotic culture of bacteria and yeast -- also forms. Usually round in shape and rubbery in texture, scoby is a valuable asset for kombucha makers as it hosts a variety of yeast and bacteria species that aid the next fermentation round. According to Chalat, kombucha usually contains 0.5% to 1.2% alcohol.
"There are now several variations of kombucha because if it's just black tea, the taste isn't so pleasant," he added. "So brewers add various types of fruits. Some add ginger, honey and so forth to make it easier to drink and easier to sell. If you look at some kombucha drinks on the market, they contain very little kombucha. The rest is fruit juice."
Sounds pretty much like the famous multi-purposed bio-fermented liquid products made by Sorawan Sirisuntarin, aka Pa Cheng? Back in around 2010, Sorawan, now in her 70s, made her "super cure" liquid from fermented plants and food waste which was then claimed to cure ailments -- even the eyes. Sorawan was arrested in 2010 for illegal production and false advertising.
"I think the two fermentation processes are different," said Chalat. "The fermentation in kombucha needs air flow and that's why brewers put a straining cloth on top of the drink instead of keeping the lid on, making the yeasts and bacteria in kombucha easier to control."
Kombucha in Thailand has fast become another diet fad, said the nutrition expert, following the do-it-yourself trend, the rising popularity of probiotic-rich products and partly due to the recommendation by Jon Jandai, founder of Chiang Mai's Pun Pun Centre for Self-Reliance whose life philosophy involves sustainable living. Kombucha communities, both online and offline, have been established where the like-minded discuss all things kombucha.
"The drink has become so widely accepted in Thailand partly because of its huge popularity in the United States," explained Chalat. In 2015, the market research firm Euromonitor labelled kombucha as "driving most of the growth in ready-to-drink teas in America". In 2014, American consumers were reported to have bought nearly US$400 million worth of kombucha. American market research company MarketsandMarkets also reported back in 2016 that the kombucha market is "poised for huge growth by 2020, growing 25% each year".
But despite such a craze and claimed health benefits, Chalat said there is actually no scientific studies in humans to stand behind those promises.
"Benefits of kombucha? The drink can be refreshing. But if asked about health gains, there is no research papers that support that. There are 13 studies but those were carried out in animals," said Chalat, adding that although a study was conducted in India by a university student on the benefits of kombucha on humans, the research turned out to be falling short of comparative studies and thus weak.
On the flip side, reports have shown a potential toxicity of kombucha in certain cases, Chalat said, especially those associated with the fermentation process and regular consumption among the sick. There have been reported cases of kidney failure and abnormal liver functions among patients who drank the fermented tea hoping to cure illnesses.
"Kombucha is not recommended for detoxification. Neither should it be consumed as a cure for diseases because there is no research to prove it.
"And for those who say kombucha contains this and that nutrients, I think it's also hard to validate those claims because there are a number of kombucha variations these days. And if nutritional benefits are what you are looking for, why not go for fresh fruits and vegetables instead?"
As with other fermented foods, making kombucha should be done in an extremely hygienic environment to reduce the risk of infection from bacteria. In Iran, 20 people were reported to have got anthrax infections from drinking contaminated fermented tea. Acetic acid is also likely to cause an upset stomach or diarrhoea in some cases.
"Kombucha causes no harm as a refreshment. But it's not a cure."