How Does Kombucha Affect My Microbiota?

Every now and then trends bloom, like a sudden spring emergence of flowers. The Kombucha cold beverage trend is a great example. Not a niche-market beverage: you see the brand leaders Kevita®, for example, in major supermarkets, and new competitors are springing up alongside them.

Kombucha is a tasty, fizzy beverage that has a tart flavor. It is made from green or black tea leaves that are fermented with yeast and bacteria colonies called SCOBY. One study found that kombucha is abundant in probiotic bacteria, notably of the Lactobacillus genera.


Most people who are fans of kombucha rightfully equate the beverage to supporting gut/digestive and immune health, and to buttressing the state of their microbiota through accelerated encouragement of friendly bacteria proliferation.

But … how, you may wonder. Fermentation is the key. And in a perfect world, we would be consuming much more fermented foods and beverages (like we used to), which helped the inner ecosystem remain at optimal health. Our ancestors, ancient and not-so- ancient, fermented foods when, among other methods, they canned fruits and vegetables and stored them in root cellars for food during the cold and food-barren winter months.

Fermentation is the use of yeasts to convert sugars (abundant and naturally occurring in numerous fruits and vegetables) to ethanol. Examples of fermented foods are vinegars, aged/hard cheeses, pickles, kimchi, kombucha and those that produce lactic acid such as yogurt and sauerkraut. Alcoholic beverages like beer and wine are fermented as well, but there are regulations on these.

As authors of one review elaborated, “Fermented products require microorganisms, i.e., Saccharomyces yeasts and lactic acid bacteria, yielding alcohol and lactic acid. Ingestion of vibrant probiotics, especially those contained in fermented foods, is found to cause significant positive improvements in balancing intestinal permeability and barrier function.”

However, fermented foods are not exactly the same as probiotics. Although many foods and beverages that are fermented contain some living bacteria that are genetically similar to probiotics and may contribute to human health in a similar way, some argue they do not provide specific health value as probiotics do, as per the definition of “probiotic.” The main job of the microbes in these foods is to ferment.

That clarified, fermented foods provide enhanced nutritional benefits and help populate the gut with friendly bacteria, such as lactic acid bacteria (LAB). One study of a wide range of commercially available fermented foods, showed that many of them are a “good source of live lactic acid bacteria, including species that reportedly provide human health benefits.”

According to the authors of said study, the nutritive benefits of fermented foods include the increased availability of bioactive molecules (such as vitamins) that stems from the fermentation process. Further, they write that many fermented foods provide live friendly bacteria that support gastrointestinal function and other health benefits such as potentially reducing risk of diabetes type II and cardiovascular diseases.

Authors of another study elaborated that during fermentation, LAB actively perform three key functions: producing biologically active peptides with enzymes such as peptidase and proteinase, synthesizing vitamins and minerals, and removing irrelevant materials (non-nutrients). LAB-produced biologically active peptides, they add, have direct human health benefits. For example, conjugated linoleic acids (CLA) support healthy blood pressure, bacteriocins are anti-microbial, and sphingolipids have anti-microbial effects.

Not all fermented foods have live microorganisms. Many foods, such as fermented sausages, soy sauces, and sauerkrauts, are heat-treated after fermentation for shelf stability, which kills the bacteria. Others, such as pickles, are not fermented but are brined, with the same effect.

Fermented foods are piquing researchers’ interest for further health attributes. One recent study sought to identify a connection between consuming fermented foods and mental health, notably the foods’ impact on depression and anxiety. Another trial showed that consuming a fermented yogurt product produced a 4% reduction in total cholesterol and a 5% reduction in LDL, suggesting that fermented products can support cardiovascular health.


Consuming enough fermented foods every day can be difficult with today’s fast-paced lifestyle and the relatively small available quantity and diversity. Also, some people just can’t “stomach” fermented foods (“igunak,” or fermented walrus, anyone?). Yes, there are many delicious options that you can’t go wrong with, but using probiotics is a great idea to support--if not optimize--your gut microbiota content and function without question.


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