I don’t understand how anyone can call kombucha tea a ‘health beverage’.
In a nutshell, here is the problem: The so-called ‘health drink’ weighs in with less than one hundred research studies behind it. When you eliminate the studies that associate kombucha tea with anthrax, death, ICU admissions and then discount the studies on ducks, rats and mice; all that remains are the studies that calls it ‘dubious’ or ‘not recommended’.(Sadjadi, No author CDC, SungHee, Majchrowicz, Ernst).
A recent blogger bragged about the ‘unbelievable health benefits’ of kombucha tea. ‘Unbelievable’ is exactly right. And yet kombucha tea is growing in popularity every day.
Now, just in case I didn’t have you at ‘anthrax’ or ‘death’, let’s go back to the very beginning and take a closer look at kombucha tea from a scientific perspective.
What Is Kombucha?
The term ‘kombucha’ refers to a combination of yeasts and bacteria which are held together in a semi-permeable membrane. It is sometimes called a ‘kombucha mushroom' or the ‘manchurian mushroom’. The reason for this is because the mixture of bacteria and yeast looks a bit like a mushroom. However, strictly speaking, it is not a real mushroom.
Commonly used microorganisms found in kombucha are Acetobacter ketogenum, Pichia fermentans, Torula and Zygosaccharomyces kombuchaensis (Kurtzman). However there can be unexpected little surprises like anthrax too (Sadjadi).
The mixture of bacteria and yeasts is sometimes referred to as a SCOBY which stands for ‘Symbiotic Colony Of Bacteria and Yeast’.
The kombucha or SCOBY is added to a mixture of sugar and tea and left to ferment at room temperature for 7 to 10 days. When prepared correctly, the pH of the tea drops down to 1.8 in 24 hours which theoretically should prevent the growth of pathogenic bugs.
The tea should not be prepared in plastic or glazed ceramic containers as there is a risk that chemicals or lead may leach out of the containers and contaminate the tea.
The end result is a mixture of tea, sugar along with the by-products of fermentation such as vinegar, B vitamins, alcohol and some other chemicals.
The theory is that the end result is high in probiotics, antioxidants and acids which should be good for you. As such it is called a ‘functional food’ meaning that it is has health benefits over and above the nutritional content. As we will see, this is a theory which is just not backed by evidence.
The usual dose of kombucha tea is 4oz to 8oz of tea per day. The tea is described as an ‘acquired taste’ and can be flavored with lemon, lime or ginger as desired.
Kombucha tea originated in China and is known as the ‘Immortal Health Elixir’. I found this confusing. I consulted with a good friend of mine who is a Traditional Chinese doctor. I asked for her opinion on kombucha tea. Dr Jing answered diplomatically (as always) and told me that ‘Some things get lost in translation between our cultures’. ‘Let’s say’ she added ‘the benefits of kombucha tea are overstated here’.
Does Kombucha Have Caffeine?
Many people ask if kombucha tea contains caffeine and the answer is yes. Kombucha tea is usually made with black tea or sometimes green tea and so does contain caffeine.
There is nothing special about the caffeine levels in kombucha tea. It just has the same amount of caffeine as you would expect in an equivalent serving of regular black or green tea.
Is Kombucha Alcoholic?
Another common question that people ask is whether kombucha tea contains alcohol and again the answer is yes. Alcohol is a natural by-product of the fermentation process. The amount of alcohol varies depending on the specifics of the fermentation process used but is usually in the range of 0.5%. The alcohol content of kombucha tea can even reach the level of alcohol in beer if it is left to ferment for long enough.
In 2010, the Whole Foods chain withdrew kombucha tea from it shelves as some of the tea had alcohol levels above the legally acceptable standard of 0.5%. (‘Honestly officer, I just had a few cups of tea!’). The suppliers have now standardized the preparation processes for kombucha tea to keep the alcohol content at 0.5% and kombucha tea is now back on the shelves.
Does Kombucha Help Detoxify?
That said, let's look at the details. The kombucha spin doctors use an article from Latvia as the key reference to back up the claims of detoxification (Vina). I really wanted to understand the data behind the claims and reached out to the corresponding author for more information. Shout out to Dr Semojonovs in Riga, Latvia who generously sent me the data.
The Latvian paper does not contain any original research but is a very thorough synthesis of available studies on kombucha. The paper suggests that kombucha tea can help the body eliminate xenobiotics such as pharmaceutical drugs and as such is good at detoxifying the body.
The authors quote studies where rats and mice were given toxic doses of acetaminophen or paracetemol along with kombucha tea. The kombucha tea was noted to have some liver protective effects (Pauline, Jayabalan).
They also looked at studies on the protective effects of kombucha tea on aflatoxin and carbon tetrachloride toxicity in rats (Jayabalan, Murugesan).
The problem is that there were no human studies. And that they were only studying actual poisons. If you haven't overdosed on acetaminophen, these results are even less relevant.
Additionally, there have been case reports of people on pharmaceutical medications who did not have the predicted detoxifying xenobiotic elimination effect. In fact, patients on medications for diabetes and HIV who took kombucha tea developed life threatening metabolic acidosis. (CDC, SungHee). This all suggests that things are not as straight forward as it might seem from studies in our four legged friends.
Does Kombucha Relieve Joint Pain?
There is only one paper quoted in the Latvian overview to support the use of kombucha tea for joint pain in humans. Unfortunately, it is only available in the Russian language (Daneilan). As such, I can’t really comment on the details of the paper.
The are no published papers in the English language on kombucha tea in arthritis in humans.
In summary, there is no evidence to support a role for kombucha tea in joint pain or arthritis.
Does Kombucha Aid Digestion?
There is really nothing to suggest that kombucha aids digestion. The theory is that kombucha tea has probiotics which would be good for digestion in general. There are no studies to back this up and most medical sources recommend yoghurts over kombucha tea because yoghurts have a much better safety profile.
Does Kombucha Increase Energy?
The scientific literature suggests that the increased levels of energy that people report on kombucha tea are probably due to the caffeine and sugar content of the original ingredients (Majchrowicz). Sounds like Red Bull to me and no one claims that Red Bull is a health drink!
Does Kombucha Improve The Immune System?
There are no studies to support an immune boosting effects of kombucha tea in humans.
There are definite risks to taking kombucha tea as an immune booster. Most people agree that kombucha tea should not be taken by people who are immunosuppressed.
Pregnant woman have a lowered immune system and are not supposed to take anything unpasteurised such as soft cheese. This means that pregnant women should avoid kombucha tea too.
There is a risk that kombucha tea may become contaminated by the mould aspergillus during the fermentation process (No author Clin Path AIDS Proj). Aspergillus can cause life-threatening illnesses in people who are immunocompromised. Hospitals are really careful about regularly sampling the environment to ensure that there is no aspergillus in patient rooms. Kombucha tea cannot be safely recommended to people who are immunocompromised in any way.
It is also worth noting that acidosis is a side effect of commonly prescribed antiretroviral therapy. Lactic acidosis is also reported side effect of kombucha tea. This means that the cumulative risk of lactic acidosis would be higher in someone on antiretroviral therapy who is also taking kombucha tea. There is at least one case report of lactic acidosis in a HIV positive patient (SungHee)
Does Kombucha Prevent Cancer?
This would be funny if it were not so serious.
The main result that shows up for kombucha tea in cancer is called ‘Dr Sklenar’s Kombucha mushroom infusion – a biological cancer therapy.’ (Hauser). Even better, it was published in Schweiz Rundsch Med Prax! Need I say anymore?
Even this article concludes that ‘there is no evidence so far to support the claim that kombucha tea offers effective biological treatment of cancer.'
Does Kombucha Help Weight Loss?
Except for one review that considered weight loss, it hasn't even been looked at. Anyone claiming a weight loss benefit from Kombucha is trying to persuade via anecdotes.
The one Latvian review paper says that there is little information available on weight loss with kombucha tea apart from personal reports. A study in 64 mice suggested that kombucha tea taken over three years did reduce body weight (Hartman). The authors of the study in mice warned against extrapolating the results to humans and also cautioned about the risks of fatalities with the tea drink.
Is Kombucha Good For You?
So just to re-cap and be super nerdy about this. There are only 79 published studies on kombucha. Interestingly, the most recent article that has been published on kombucha is actually a retraction of an earlier kombucha study (Barati). The study was retracted because of plagiarism and general unprofessional practices. So that whittles the total evidence base on kombucha down to 77 articles!
Let’s compare this to another health beverage like green tea. Green tea has over 2000 publications.
In summary, there are very few studies on kombucha. The vast majority of the published studies are very negative about kombucha.
And just to be clear, I am not the only clinical researcher saying this. A 2019 review from the University of Missouri reviewed 310 (pre-clinical and clinical) studies and found only one positive clinical study (Kapp). The paper suggested that the mass of pre-clinical claims relating to kombucha really need to be tested in actual humans.
Bottom Line: Not only is it not "good for you" in any meaningful sense, it is potentially very dangerous, as you're about to read.
What Are The Side Effects Of Kombucha?
The side effect profile of kombucha is not good at all.
In 1995, the CDC, FDA and the Iowa Department of Public Health investigated two cases of unexplained illness which were thought to be due to Kombucha tea. One was a 59 year old lady who died of lactic acidosis (CDC, MMWR). An autopsy did not reveal any cause of death. She had been drinking Kombucha tea daily for the two months prior to her death.
Less than two weeks later, a second lady was admitted to the same hospital with lactic acidosis. She also had been taking kombucha tea for the previous two months. Fortunately, she was resuscitated from a cardiac arrest and survived. Both women were home brewing kombucha tea and had sourced their kombucha mushroom from the same person. Coincidence maybe? The CDC, FDA, Iowa Department of Public Health and I don’t think so!
There are other case reports of life-threatening lactic acidosis and hepatoxicity with kombucha tea (SungHee, Geleda).
An Iranian clinic reported ten cases of skin anthrax which were found to be related to unhygienic preparation of kombucha (Sadjadi).
Clinicians in Texas also published four case reports of patients who were admitted with kombucha related jaundice, gastrointestinal upset and presumed allergic reactions (Srinivasan).
Kombucha tea can exacerbate peptic ulcer disease and can effect medications which are sensitive to the pH environment of the stomach.
So yes, there are possible side effects. Really bad ones.
Where Can You Get Kombucha?
Kombucha tea can be brewed at home, ordered online or bought from a number of health food stores.
Home brewing of kombucha seems to be pretty popular. The two ladies who had kombucha related toxicity in Iowa had brewed their own kombucha tea from SCOBY disks sourced from the same person.
Here is the odd thing. Most people would not eat food without knowing who had prepared it and whether it had been hygienically prepared. I can’t begin to imagine ordering a SCOBY disk online from any randomer!
Seriously, if you've read this far you get how important this is... please do not buy it.
The currently available data on kombucha shows that this it is in no way a ‘health drink’. I can’t think of any single situation where the possible benefit of this drink would outweigh the known risks.
I never imagined that I would recommend Red Bull. Things change! Given a choice between kombucha tea or Red Bull with a yoghurt, I would pick the ‘wings’ without the anthrax any day.