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5 Kombucha Dangers - Including Alcohol, FODMAPs & Mold

Researched and Written by:
Richelle Godwin, RDN Richelle Godwin, RDN Jenna Swift, APD Dietitian Jenna Swift, APD Dietitian

If you’ve seen kombucha in the news lately, it was probably because a reporter was more or less calling it moonshine for hipsters! And suggesting that if you drank it, you were basically drinking light beer. Well, in this article, I want to separate fact from fiction when it comes to the top 5 potential dangers of kombucha. And as a registered dietitian, I’m going to of course avoid the hysterical news reporting, and just serve you up the facts. Let’s go!

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Table of Contents

    Danger 1: Alcohol in kombucha

    So the number one issue that has damaged kombucha’s health credentials in recent years, are reports that it can have a lot more alcohol in it than people think. 

    But with so many conflicting stories, our research team at Essential Stacks and I decided to do some digging. 

    Alcohol in commercial kombucha

    When it comes to commercial kombucha - the kind you buy in a store - here are the simple facts we found...

      So yes, commercial kombucha does contain some alcohol.  But in order to be sold to the public it has to have Less than 0.5% alcohol.  Meaning you’d have to drink 3 liters - or nearly a gallon of kombucha - to match the alcohol in just 1 bottle of beer. 

      But with that said, there have been stories of commercial kombucha being tested in laboratories for alcohol content and coming in at much higher numbers. 

      The most noteworthy investigation occurred back in 2010 and was led by the FDA.  It revealed over the counter brands Ranged from 0.5 to 2.5% in alcohol content. 

      And additional studies not long after this found similar results.
      This was the scandal of the decade in the fermented drinks world...our very own Kombuchagate!   

        Some manufacturers were clearly understating their alcohol content.  While others were shipping and storing it at room temperature - because, well, it’s cheaper!  

        And in doing so they failed to take into account bottled Kombucha's amazing ability to continue fermenting after bottling - something that Increases the level of alcohol.  And with many manufacturers saving costs by shipping and storing at room temp, this was a big deal. 

        But just like Nixon, this controversial moment in kombucha history is largely a thing of the past.  

        It seems the watchful eye of the FDA, along with the Threat of large fines, encouraged manufacturers to modify their processes & prioritize refrigerated storage.  Thereby ensuring kombucha stays Below the 0.5% alcohol from time of bottling through to expiry.  

        And they even formed their own industry watchdog to police internally.  The brewers must have watched a lot of CSI Miami, because they decided to call their new organization...wait for it...Kombucha Brewers International - or the KBI for short!

          Meanwhile, other manufacturers took the easy way out and simply started Pasteurizing their kombucha.  This involves heating the kombucha to Kill all bacteria & yeast and thus end the fermentation process. 

          But with pasteurized kombucha, you’re Missing out on the probiotic benefits of real kombucha.  And although some companies do add probiotics back in after this process, they are more like a supplement, and not the same as probiotics made during the brewing process.

          Whichever brand you choose to buy, let’s remember that kombucha in all its forms is still a lot healthier than normal alcoholic beverages, not to mention sugar-laden sodas!

          Okay, so we’ve covered commercial kombucha.  But what about the alcoholic content of Homemade kombucha

          Alcohol in homemade kombucha

            Well, it depends on how long you ferment it, how much sugar you feed it, and what temperature it is kept at. 

            More time, more sugar and higher temperatures mean More fermentation, and thus Higher alcohol levels. 

            Generally speaking though, Homemade kombucha will have a Higher alcohol content than commercial kombucha, typically sitting between 1% to 3%.

            So to sum up here, there is some alcohol in kombucha and it does vary a lot depending on all the factors we just looked at.  But if this still remains a concern for you and you don’t want to drink pasteurized kombucha, I have a geeky idea for an alcohol measurer. 

            You may see them called hydrometers or refractometers, and they’re actually really inexpensive pieces of equipment suitable for at-home testing purposes.

            Danger 2: Drinking too much kombucha

            I know whenever we find a new health food our desire is to go full Cookie Monster on it, so we can get more and more of the goodies inside.  But drinking excessive amounts of kombucha can potentially cause some real problems.  

            Let’s take a look at some of the Potential side effects...

            So the first one is abdominal discomfort - which could be in the form of bloating or diarrhea, or if you’re really lucky, both! 

            Kombucha can cause this feeling because it contains FODMAPs, which stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. 

            Put simply, FODMAPs are carbs that some people find hard to digest, such as people with irritable bowel syndrome.  The main FODMAPs you’ll find in kombucha are Fructans, and in some brands you’ll also find Sugar alcohols, which are used to flavor the kombucha. 

            If this is a problem for you, then Limit your kombucha to 6 oz or 180 ml / day, since this has been measured as a low FODMAP serving size by Monash University.  

              The next potential side effect of too much kombucha is tooth decay.  This is an interesting one.  You see, while kombucha doesn’t have much sugar, it is filled with organic acids that protect the drink from spoilage. 

              And these acids can potentially reduce enamel, while increasing Tooth sensitivity and discoloration

              If this is something you’re worried about, drinking your kombucha with a straw can make a big difference.

              Now, there are many other potential side effects that people have claimed are due to excessive kombucha consumption, such as weight gain, headaches and reflux.  But when you dig into the claims you quickly realize they are not really unique to kombucha.

              For example, yes kombucha may cause reflux in some people due to the way the fizzy bubbles can create pressure in the gut.  But so too can any other carbonated beverage.

              Meanwhile, we have seen other more serious side effects of kombucha consumption mentioned in research papers.

              • Suspected liver damage
              • Jaundice
              • Toxic hepatitis
              • Hyponatremia
              • Hepatotoxicity
              • Metabolic acidosis
              • Pellagra 
              • (Vitamin B3 niacin deficiency)
              • Symptomatic lead poisoning
              • Shortness of breath 

                Unfortunately, when you actually dig into the literature, there is Very little context around these cases, especially in terms of their connection to kombucha.  Also from what we could see they tended to Exclusively involve people with pre-existing conditions.  So more research is needed to confirm if any of these are true risks of kombucha.

                What we can say though is that there are certain groups of people who should avoid kombucha and we’ll look at that next. But otherwise, for healthy individuals we Just couldn’t find enough evidence to substantiate additional risks.  And hey, we are here for the research, not for the fear-driven clicks!

                So If you’re a healthy individual, kombucha is Safe to drink in moderation.  In fact, the CDC has confirmed this and stated 4 ounces or 120 ml, enjoyed 1 to 3 times a day, is fine. 

                Danger 3: At-risk people & kombucha

                Sadly, for a few people, kombucha is probably going to be a bad idea, even if it is fermented by the angels!  So if you fit into any of these groups, consider Avoiding kombucha.

                1. Pregnant or lactating - if baby is on board or on breast, then kombucha is arguably a danger given the Alcohol content and Risk of pathogens such as listeria.  And of course, as a tea-based drink, there are small amounts of Caffeine in kombucha, which is just another reason to hit the pause button... for now. 
                2. Histamine intolerance - if you have nightmares about being attacked by a bowl of histamine-laden sauerkraut, then add kombucha to your no list, as this fermented drink also contains histamines. 
                3. Any one suffering from a compromised immune system - for example due to cancer.  Should also consider avoiding kombucha as it has the potential - however low - of being contaminated by pathogenic microorganisms during the fermentation process.
                4. Alcohol addiction - if you suffer from this, then consider skipping kombucha, especially homebrewed kombucha, as even trace amounts of alcohol can greatly disrupt the recovery journey.
                5. Any individuals that have experienced kidney, lung or liver disease, or are otherwise at greater risk of acidosis - you should also avoid kombucha.  You see, acidosis is a condition where too much acid is in the blood.  And given that kombucha can be quite acidic, the two don’t go well together.  In fact, the only death we could find possibly linked to kombucha involved a person with kidney disease, who drank kombucha daily for 2 months, then developed severe acidosis and subsequently died from cardiac arrest.  Thankfully, the CDC and FDA report from the 1995 investigation into the death concluded kombucha did not cause the severe illness. So if you ever see someone suggest kombucha consumption can be fatal, demand they show you their research.

                Danger 4: Contamination of kombucha

                If you’re making kombucha at home or buying it from say the farmers market, you should give a little thought to the risk of contamination.  Just like you would with any fresh food.  For kombucha, contamination can come from 3 main sources.

                • Firstly, poor handling of ingredients, especially the SCOBY - we’re mainly talking about potential contaminants coming from unhygienic hands and nails here.  So to avoid this risk when brewing, pretend you're Dr McDreamy in Grey’s Anatomy and scrub your hands and nails like you’re doing surgery. 
                • Contamination can also come from poorly cleaned equipment - meaning brewing jars or utensils that haven’t been washed in boiling hot soapy water or haven’t been washed for long enough.  So once again, really let your inner clean freak out when brewing kombucha!
                • The third source of contaminants comes from using unsafe equipment - this is really interesting (and actually quite scary!).  So as we talked about before - kombucha is really acidic.  And it turns out if you brew it in certain containers, this acidity can cause chemicals and heavy metals to leach from the container itself!  In fact, cases of lead poisoning have been reported when kombucha was brewed in a ceramic pot over an extended period of time.  Safe to say, stick to glass jars for all your kombucha brewing adventures!

                Danger 5: Mold in kombucha

                The other potential danger when making kombucha at home is mold, which can grow in your brewing vessel, usually on top of your SCOBY. 

                The most common types of mold found in kombucha are Aspergillus and Penicillium.  And as toxins, they are obviously not good for our health, and have indeed been found to create acute and long term problems in people.  

                To help you avoid this danger, here are my 2 big tips...

                • First, Check your SCOBY regularly for any signs of mold.  Think dry and fuzzy patches - either blue, green, white or black in color.  And it kinda looks like this. 
                • Second, Measure the pH of your kombucha regularly.  Okay, so this one is worth explaining!  You see, as kombucha brews over 1-3 weeks the bacteria produce organic acids, which make the liquid more and more acidic.  And these smart little guys do this because they know mold or other harmful pathogens can’t survive in highly acidic environments.  In other words, the kombucha works to protect itself!  Now, you can actually measure the acidity of your kombucha with strips that test for pH levels.  A lower pH level means more acidity.  And so, ideally your kombucha should Start brewing at or under <4.5 pH and then drop further to 2.5 - 3.5 pH over the brewing period.  If you can see that, then your organic acid superheroes are doing their job and you likely don’t have to worry about the potential danger of mold. 

                Our conclusion

                So now you’ve seen the real facts about kombucha.  And weighing it all up, it doesn’t look that scary right?!  Particularly if you take into account all the potential health benefits of kombucha, which I discuss here.

                And so for healthy people, 4 - 12 oz / day - which is roughly 120 - 360 ml / day - is perfectly fine.  Meanwhile, for those of you with IBS, or those who experience some abdominal discomfort when drinking too much kombucha, Limiting yourself to around 4 - 6 oz / day  or 120 - 180 ml / day  a day - can work. And of course, for those at-risk individuals we talked about before, kombucha does present some real risks and is worth avoiding.  

                And for those of you that want to make it at home, just make sure to be extra hygienic to avoid the potential risks of contamination or mold growth.  But at the same time, don’t stress too much - after all, us humans have been making kombucha at home for centuries!

                Evidence Based

                An evidence hierarchy is followed to ensure conclusions are formed off of the most up-to-date and well-designed studies available. We aim to reference studies conducted within the past five years when possible.

                • Systematic review or meta-analysis of randomized controlled trials
                • Randomized controlled trials
                • Controlled trials without randomization
                • Case-control (retrospective) and cohort (prospective) studies
                • A systematic review of descriptive, qualitative, or mixed-method studies
                • A single descriptive, qualitative, or mixed-method study
                • Studies without controls, case reports, and case series
                • Animal research
                • In vitro research

                1 comment

                • Hi i keep looking for info if kombucha has heavy metals in it. Ive read that even organic green tea may have over the safe amounts. And plenty of brands use organic green tea. Do you have any knowledge about this possibly?

                  Jeri Balco

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