Does kombucha live up to the hype?
Kombucha is one of the newest health crazes to hit the media. As dietitians, we often get asked if it’s a healthy choice or just another food fad. Read on to see what the science says and decide for yourself.
What is it?
Kombucha is a fermented tea drink that has become popular as part of the functional food movement. Its popularity is likely related to health claims and a concurrent rise in scientific research into the gut microbiome.
Kombucha is made by fermenting tea (generally black, green or oolong), sweetened with sugar with the addition of Symbiotic Culture of Bacteria and Yeast (SCOBY).
During fermentation, the yeast converts the sugar to alcohol and the bacteria convert that alcohol to organic acids (for instance, acetic acid). The resulting beverage is a refreshing, lightly effervescent drink with a subtle sour flavour.
Commercial brands then add a range of flavours for consumer choice, such as ginger and lemon or raspberry.
What is SCOBY?
SCOBY is a gelatinous, cellulose-based biofilm comprising various acetic acid bacteria and yeasts.
The species comprising the mixed cultures vary from preparation to preparation—so you never really know which strains of bacteria (or probiotics) you’re getting in each bottle!
Kombucha is commonly identified as a drink that improves gut health and provides a source of probiotics. Much of its appeal is attributed to its low sugar content and reported health benefits. It’s popularity as a functional food is driven by claims of the beverage being that it is: antioxidant-rich and anti-inflammatory; reduces of cholesterol levels and blood pressure; lowers cancer risk; improves liver function; improves the immune system; and encourages better gastrointestinal function.
The rise in research and knowledge gained about the importance of the gut microbiome for our health has only fuelled the rise of this so-called super food.
What the research says
Direct evidence supporting the health benefits of kombucha for human health is lacking. A 2003 systematic review found no clinical studies related to kombucha.
A more recent systematic review published this year has updated our knowledge. While the review did find existing studies, there was no data on the empirical health benefits of kombucha in humans. Despite this fact, significant space at supermarkets, gourmet greengrocers and health food stores is dedicated to kombucha drinks and related products.
In the non-human studies reviewed, kombucha’s health benefits are derived from the tea and products of fermentation, including glucuronic acid, acetic acid, polyphenols, penols and B-complex vitamins.
These nutrients are associated with liver, immune system and gastrointestinal benefits as well as containing anti-cancer properties. However, these benefits should be considered in context. To date, the research only exists from studies in rats, pigs, mice, ducks, dogs, cattle and chickens. Humans might be a horse of a different colour!
Basically, more research is needed to confirm the health benefits of kombucha. The effect in humans should be tested specifically in clinical trials before the health claims we hear or read about can be believed.
For now, kombucha (especially the sugar-free brands) can be considered a healthier alternative to commercial soft drinks.
Sue Radd is an Advanced Accredited Practising Dietitian and one of Australia’s leading nutritionists and health communicators. Her most recent book Food as Medicine: Eating for Your Best Health received the Gourmand World Cookbook Award for Best Health and Nutrition Book in the world for 2016.