Does Kombucha Live Up to Its Health Hype?

Kombucha offers potential health benefits due to its water-soluble vitamins, particularly vitamin B12. This makes it an appealing option for vegans. However, it’s crucial to be cautious, especially with homemade kombucha, as it can pose risks. For healthy adults, it’s advisable to limit consumption to half a glass per day, and pregnant women should consider avoiding it altogether.

What exactly is kombucha?

Kombucha is often informally described as a thick, jelly-like substance living in containers filled with sweet tea. Contrary to popular belief, it’s not a mushroom but rather a symbiotic culture of bacteria and yeast, known as SCOBY. These microorganisms play a pivotal role in turning sweet tea into the fermented beverage we know as kombucha.

Within the tea, the bacteria and yeast progressively consume its sugar and, in return, enrich the mixture with various byproducts of their metabolic processes: alcohols, carbon dioxide, and organic acids. After about 5-7 days, this results in a mildly carbonated beverage with a subtle tang. Allowing the kombucha to ferment for too long can make the drink overly sour and unappetizing.

Similar to other fermented products like kefir or sauerkraut, kombucha follows a comparable maturation process based on the same underlying principle.


Why Kombucha Research Poses Challenges

Studying the properties of kombucha can be quite demanding due to its unique nature. Each SCOBY (Symbiotic Culture Of Bacteria and Yeast) has a distinct composition, and the variety of microorganisms fluctuates significantly during different fermentation stages. For instance, multiple yeast species coexist within the same biofilm.

The fermentation process begins with yeast that prefers a less acidic environment, followed by acid-resistant species. Therefore, before fermentation kicks in, the SCOBY usually hosts yeast that thrives in a neutral environment. After fermentation is complete, it harbors those that favor an acidic one.

This means that even within the same jar, kombucha harvested at different times will have varying compositions. The final characteristics of the beverage depend not only on its composition but also on the quantity of microorganisms within the biofilm.

Yet, even if all SCOBYs were identical worldwide and the kombucha made from them was harvested precisely, the complexity of microbial fermentation remains a significant challenge. Factors such as temperature, dissolved oxygen levels, and the tea’s nutrient content all influence the final product.

Ensuring a consistent composition for this beverage is practically impossible, making it difficult to conduct research on kombucha with changing compositions. As of now, direct evidence confirming the health benefits of kombucha is still lacking.

The Health Potential of Kombucha

To understand what can be expected from kombucha, we must rely on general studies and consider it as a typical fermented product.

The impact of fermented foods on health depends on three factors:

  1. The types of microorganisms involved in fermentation.
  2. The composition of fermentation products created by these microorganisms.
  3. The composition of chemical substances already present in the substrate that remain unchanged during fermentation. In the case of kombucha, this includes tea, which contains bioactive compounds like polyphenols.

Kombucha as a Probiotic Source

Probiotics are live microorganisms that may offer health benefits. There’s evidence that they can be beneficial for:

  • Preventing antibiotic-associated diarrhea.
  • Supporting the health of individuals with ulcerative colitis.
  • Preventing enterocolitis and sepsis in preterm infants.
  • Treating infant colic.
  • Treating periodontal diseases that affect the tissues around the teeth.

However, there’s limited convincing evidence that probiotics provide benefits for other purposes.

It’s important to note that not all microbes found in fermented foods are beneficial for health. Specific strains of yeast, like Saccharomyces boulardii, certain lactic acid bacteria from the Lactobacillus group, and Bifidobacterium from the Bifidobacterium group can function as probiotics. Just because one strain helps prevent a disease, it doesn’t mean others from the same group will have the same effect.

In the biofilm of the kombucha SCOBY, there are primarily acid-resistant yeast cells of various species, and some contain Saccharomyces boulardii. However, to gain probiotic benefits, children should consume 5 to 10 billion colony-forming units (CFUs) per day, while adults should have 10 to 20 billion CFUs daily. Dry yeast from probiotics in capsules or powder provides the required amount, whereas kombucha itself doesn’t, as it has too few yeast cells.

A similar situation exists with the bacteria in kombucha. The majority are acetic acid bacteria, primarily from the genera Komagataeibacter, Gluconobacter, and Acetobacter, and they lack probiotic properties. Lactic acid bacteria from the Lactobacillus group may accompany these acetic acid bacteria, but it’s uncertain whether the strains found in kombucha have beneficial properties. Even if they do, their concentration in kombucha is too low to provide health benefits. Bacteria, like yeast, prefer to live in the biofilm rather than the liquid. Bifidobacteria are generally absent in kombucha, so it’s inaccurate to label it as a ‘natural probiotic.’

Kombucha as a Source of Fermentation Products

During fermentation, kombucha becomes enriched with carbon dioxide gas and contains a small amount of ethanol, acetic acid, water-soluble B-group vitamins, vitamin C, and some minerals, including manganese, iron, chromium, copper, zinc, lead, cobalt, cadmium, and nickel.

The presence of ethanol and acetic acid helps prevent pathogenic microbes from invading the SCOBY, reducing the risk of contamination. However, the levels of these compounds in the beverage are so low that healthy adults, excluding pregnant women, won’t become intoxicated by alcohol or poisoned by the acid.

The most valuable components of kombucha are the B-group vitamins and vitamin C.

Vitamin Content in 100 ml of Kombucha:

VitaminContent in KombuchaDaily Norm
B174 mg1.5 mg
B652 mg2 mg
B1284 mg3 mg
C151 mg100 mg

To put it simply, kombucha is a source of water-soluble vitamins, primarily vitamin B12, which can be beneficial, especially for vegans who may lack this vitamin since it’s not found in plants. However, it’s important to note that high doses of vitamins C, B1, and B6 in kombucha don’t significantly impact your health more than products with much lower levels of these vitamins. The body can only absorb as many water-soluble vitamins as it needs, and the rest is excreted in urine.

Kombucha also contains trace elements like iron, copper, manganese, chromium, and zinc, but the quantities are quite small. For instance, 100 ml of kombucha contains only 46.2 mcg of manganese, while adults need 2 mg daily. So, kombucha isn’t a significant source of these elements.

While kombucha generally has low lead levels, it’s worth noting that even the minimal presence of lead can pose health risks. The beverage contains only 0.005 μg/mL of lead. To put this in perspective, lead poisoning typically occurs when children have blood lead concentrations of 0.2 μg/mL and adults have concentrations of 0.1 μg/mL.

Polyphenols in Kombucha: What You Need to Know

Kombucha isn’t just a trendy beverage; it’s also a potential source of healthy compounds known as polyphenols. Polyphenols aren’t limited to tea; you can find them in drinks like pomegranate juice too. These natural antioxidants come from plants and play a crucial role in combating unstable molecules called free radicals, which can harm your body’s cells.

Some studies suggest that the polyphenol content in kombucha remains similar to what you’d find in tea. However, it’s not as simple as drinking a glass of kombucha for cell protection. To truly benefit from these antioxidants, you need a substantial amount – we’re talking about at least 570 milligrams of polyphenols in one go.

Among different teas, green tea is a standout when it comes to polyphenols. A mere 100 grams of dried green tea leaves can pack up to 20 milligrams of polyphenols. Even if you brew this tea and let it undergo the transformation process to become kombucha with a scoby, you’ll still end up with relatively low polyphenol levels in a single glass of the final drink. This holds true even if you theoretically manage to extract all the polyphenols during brewing, which isn’t always the case in practice.”

Can Kombucha harm you?

Kombucha can not only harm but also kill, although this happens rarely. For example, in Iowa in 1995, two women were poisoned by Kombucha, which they had been drinking their homemade brew every day for two months. One of them died.

Non-lethal cases of poisoning occur more frequently. There are several stories of people suffering from food poisoning, liver damage, acute kidney failure, and even Siberian ulcers as a result of Kombucha poisoning.

In some cases, pathogenic microorganisms, such as aspergillus, have been found in the analysis of Kombucha. However, the cause of poisoning often remains unclear, possibly due to an individual’s reaction to this drink.

But there’s an important nuance: most of those who got poisoned drank homemade Kombucha. I didn’t find cases where someone got poisoned by store-bought Kombucha. However, since there are no standards for preparing this drink, it’s impossible to completely eliminate the risk of poisoning from “commercial” Kombucha.

How to properly drink kombucha tea

How much and how often can you drink kombucha tea?

After analyzing all reported cases of kombucha poisoning, experts from the American Center for Disease Control and Prevention have concluded that this beverage should only be consumed in quantities of 125 ml per day, which is not more than half a glass.

Can children consume kombucha tea?

Although in recommended doses, kombucha does not pose a health risk, it contains lead, which children are more susceptible to than adults. To minimize the risk, scientists recommend that parents give kombucha to children only occasionally – not more than once every one to two weeks.

Can pregnant and nursing women consume kombucha?

No one knows for sure whether it is harmful for pregnant women to drink kombucha since this has not been tested yet. Most specialists believe it is safer to abstain, as today it is considered that pregnant women should not consume alcohol even in the smallest quantities.

There is another reason as well. Although the microorganisms living in SCOBY successfully resist the invasion of pathogens, unpasteurized kombucha can become moldy. Or harmful bacteria may enter it after it is bottled. Healthy adults’ bodies are likely to handle this, but during pregnancy, the effectiveness of the immune response decreases – this is necessary to ensure that the mother’s built-in antimicrobial safety system does not harm the child. Therefore, it is safer to abstain from consuming kombucha during pregnancy.