GT Kombucha flavors and other brands on store shelves

Kombucha Benefits May Be Fake, With Dangerous Side Effects

[toc]Thanks to the internet, both the good and bad things about any given food are often exaggerated. Though at least most of the time, the things being said are rooted in some science. Say a cancer study done in the lab or a human weight loss trial.

Not the case with this funny-tasting sour beverage.

What people say about it deviates so far from reality, it’s hard to fathom where they are even coming up with the stuff.

Outright fabrication would be the only logical explanation for some of the alleged perks. Hair growth? That’s definitely a hoax or scam. Others are based on personal anecdotes which are put forth as evidence.

So might it actually be worth the $4 per bottle? Is it safe to drink kombucha everyday?

Let’s get to the bottom of this.

What is kombucha?

Kombucha is a fermented beverage made using green or black tea leaves. Bacteria and yeast are added to the tea and feed off of an added sugar. During this fermentation, the sugar is digested by these microorganisms. What remains after are high amounts of acid and a small amount of alcohol. This it why kombucha tastes like vinegar, because the sugar is mostly gone. If left unpasteurized, living probiotics will be inside the bottle too.

Health-Ade Kombucha nutrition facts label
This nutrition facts label for the popular Health-Ade brand is typical of what you will see. Normally it’s gluten free and vegan.

Some call it Manchurian mushroom tea. Not because it has mushrooms in it or because it’s made with mushrooms, but rather because yeast is a type of fungus. The mushroom moniker is used generically to describe them.

Manchuria, a large region spanning Northeast China and beyond, is where some believe it originated. Proponents and marketing by kombucha brands often claim the Qin dynasty (220 BC) hailed it as “the tea of immortality” but that is based on many assumptions and it’s not even clear if the standard recipe came from China.

In the 4th century AD, a Japanese physician named Kombu imported it to his country. He claimed it offered digestive benefits for the Emperor Inkyo. Doctor Kombu is where the name came from, but not the recipe itself.

Its history is murky. No one can say for sure where kombucha comes from originally. (1)

Health studies

No one expects a given food to undergo the same caliber of FDA registered clinical trials as a medication. Though some sort of human clinical trial to at least suggest the possibility of a health claim is quite common, even with food. Such studies are not adequate for proving a benefit, but they do provide preliminary evidence.

So what do the human scientific studies on kombucha have to say?

Not much…

clinical trials for kombucha in PubMed database

That’s right, out of the nearly 30 million medical citations in the PubMed database from across the world, there is not a single human study for this purported miracle drink.

Compare that to something like curcumin, the active ingredient in turmeric. There are over 180 clinical trials published for that. Even for relatively obscure superfoods, like rhodiola rosea, there are over 40. Often times, it is the food/supplement manufacturers which fund these studies, at least in part.

GT Cocokefir price of $15 at grocery store
GT even sells an insanely expensive “Cocokefir” drink at nearly $15 a bottle! Can’t they use some of that dough to fund medical research?!

According to Forbes, this product is expected to reach annual sales of $1.8 billion by 2020. It already occupies around 1/3 of the “functional beverage” refrigerated section of a Whole Foods store. The largest brand, GT Kombucha, is a private company so no one knows how much money they make, but by some estimates their revenue is around $500 million per year. (2)

Is kombucha good for you? Because if it really is, why aren’t these manufacturers ponying up a little cash to conduct some low cost human studies at a university. That doesn’t require millions. It can be done for tens of thousands of dollars, which is a drop in the bucket for some of these companies if they truly believe in their product and the health advantages.

It’s safe to say that there isn’t hundreds of millions in sales for rhodiola rosea supplements, yet there still seems to be funding available for human studies!

There’s zero human clinical data to support any claim about this fermented drink. So let’s take a look at the benefits being alleged and what science there may be – if any – to support a given claim.

10 benefits of kombucha

1. Probiotics

Are there probiotics in kombucha? Yes, but how much there is inside can be misunderstand. It’s made using SCOBY, which is the acronym for Symbiotic Colony of Bacteria and Yeast. It sounds diverse, but the probiotic profile after brewing paints a different picture.

As published in the science journal Food Microbiology, five different samples were tested and it was found that just one probiotic made up the vast majority of the content; Gluconacetobacter was around 90% of the total probiotic content in all tested samples.

Measured after ten days, here’s a full list of the probiotics in kombucha. Each number is the percentage out of the total probiotic content. Five different individual and commercial suppliers from around the world were used.

Probiotic Canadian Supplier #1 Canadian Supplier #2 Ireland Supplier UK Supplier US Supplier
Acetobacter 0 0 0.19 0 0
Gluconacetobacter 92.17 93.16 87.62 94.26 95.73
Lactobacillus 5.96 6.17 9.59 1.44 3.47
Lactococcus 0 0.23 0.19 0 0.18
Leuconostoc 0 0 0 0 0
Bifidobacterium 0 0 0 0 0
Thermus 0.66 0 1.62 3.73 0
Allobaculum 0 0 0 0 0
Ruminococcaceae Incertae Sedis 0 0 0 0 0
Other 1.22 0.45 0.79 0.58 0.61

As far as potentially beneficial yeast, over 95% of what was in these samples was found to be the Zygosaccharomyces species. (3)

It is true that some brands on the market claim to have more types of probiotics inside, but they are most likely adding those in after the fermentation process.

Wouldn’t it be much more cost-effective to simply buy a good probiotic supplement instead, rather than spend $3.50+ per drink?

2. Weight loss

You may hear testimonials and read reviews of it being a good diet drink, but without any human studies, there is no proof that kombucha is good for weight loss. The only confirmed benefits which may help are found can be found on the nutrition facts label:

  • How many calories there are in kombucha ranges from 25 to 50 calories per 8 ounce serving. This is a lower calorie count than any juice or sweetened soda.
  • The low sodium content – typically 10 mg or less – may help with reducing water weight, but only if you drank it as part of an overall low sodium diet.

3. Boosts energy

caffeine moleculeThis benefit has some merit. It’s made with tea leaves, which means there’s caffeine inside. Even decaffeinated will contain a little.

How much caffeine is in Kombucha GT Synergy? The manufacturer, Millennium Products, has entries for 9 of their flavors in the USDA National Nutrient Database. They provide details for calories, carbs, sugars, and some vitamins and minerals, but none of the entries list the mg of caffeine inside. (7)

Even though GT doesn’t publish the number, one website emailed the company to find out and the response reportedly said (8):

“GT’s Kombucha is considered naturally decaffeinated and contains anywhere from 8 mg to 14 mg per 8 oz. serving.”

That’s too little to provide noticeable energy for most people. Consider the fact that a Grande Starbucks Pike Place coffee contains 330 mg of caffeine per 16 oz. If compare that on an ounce to ounce basis, it’s about 1,100% to 2,000% more caffeine.

Owned by Pepsico, Kevita Master Brew kombucha reports 80mg of caffeine on the nutrition facts, but that’s an outlier. High caffeine is not the norm for a typical fermented tea recipe.

4. Detox

Whether it’s activated charcoal, apple cider vinegar, or some other superfood, detox claims are almost always pseudo-science. Yes, activated charcoal binds to certain toxins in the stomach, but that’s used during acute poisoning treatments. There’s no evidence of it pulling toxins from outside of whatever is sitting in your stomach or digestive tract.

When you compare kombucha vs. apple cider vinegar, one thing they have in common is they are made through fermentation. Another similarity? Both are claimed to be detoxing agents, despite no human studies to even suggest the possibility.

Although it would not be “detox” per se, there are animal studies which suggest kombucha might help protect the liver, which of course is an organ that plays an important role in filtering out toxins.

  • In a study with mice fed a known liver poison (carbon tetrachloride), it was claimed that the antioxidants in kombucha appeared to offer protective effects for their livers. (14)
  • Another study with mice found that it was able to reduce oxidative stress in the liver caused by the poison tertiary butyl hydroperoxide (TBHP). (15)

5. Better skin appearance

There are blogs which claim that drinking it can boost your skin’s elasticity and tone. Some even purport it can help with acne, eczema, psoriasis, rashes, warts, and athlete’s foot. Instructions range from drinking it daily, to applying it topically to your face. The latter advise includes recipes for lotions and toners.

The problem is there’s no validation for any of these. Some kombucha skin benefits might exist thanks to the B vitamins certain brands contain; B1, B2, B3, B6, B9, and B12. Depending on the brand, an 8-ounce serving typically offers 20-25% of your daily value for each. However unless you are deficient in those, it seems unlikely that you would be realizing skin care advantages above and beyond what you’re already getting from your dietary intake of these vitamins.

6. Faster wound healing

albino lab ratUsing 24 albino rats, scientists treated half of them with Nitrofurazone/Furacin ointment (a prescription antibiotic for burns) and the other half with kombucha fungus. They claimed that by day 20, the healing of both was comparable, with “no significant differences observed.”

The problem?

This several year-old study out of Iran was eventually found to be flawed and therefore retracted. That was the only paper related to wound or scar treatment. (4) (5)

7. Antioxidants

Are there antioxidants in kombucha? It’s made with black or green tea, both of whose leaves come from the Camellia sinensis plant. Therefore it is a source of at least some epigallocatechin-3-gallate (EGCG), theaflavin, and gallic acid.

A couple years ago, the following paper was published which measured how much antioxidant activity the drink has (6):

Evaluation of the Stability of the Total Antioxidant Capacity, Polyphenol Contents, and Starch Hydrolase Inhibitory Activities of Kombucha Teas Using an In Vitro Model of Digestion

They reported that the amount of antioxidants increases the longer the beverage ferments. However like the last paper, this study was later found to be flawed and retracted. The ORAC value reported in it cannot be relied upon and we are aware of no other sources for it.

ORAC testing to measure antioxidant content is expensive, but a couple thousand dollars is a small price to pay for a manufacturer selling hundreds of millions worth of this drink. It would be cheap research for the bestselling brands like GT’s, Kevita, Lion Heart, and Health-Ade kombucha. Publishing such data would help lend credence to the antioxidant claims.

ORAC isn’t a measure of antioxidant activity inside a human body, as that is impossible to measure. But by having a measured value, it would at least provide some sort of scientific support for the “antioxidant-rich” claims that the media is making… based currently on almost nothing.

8. Good for diabetes

diabetes blood sugar test stripsThe unflavored raw and organic recipes will have low sugar content and therefore, a minimal impact on blood sugar. Glycemic Index (GI) testing to determine the exact effect has not been done.

There is a non-human study on the topic of diabetes.

Diabetic rats were orally given a daily dosage of kombucha, equal to 5mL (1 teaspoon) per kilogram (2.2 lbs) of their body weight. After doing this for 30 consecutive days, the scientists noted the following when comparing to rats who weren’t getting it.

  • An apparent delay in their absorption of LDL cholesterol, which is the bad kind.
  • A “significant increase” in the good kind, HDL cholesterol.
  • Positive changes were seen with liver and kidney markers; lower aspartate transaminase, alanine transaminase, gamma-glytamyl transpeptidase, creatinine, and blood urea nitrogen.

These would be considered protective benefits in type 2 diabetics, but remember this is only a rat study and it is unknown if the same happens in humans. (9)

9. Joint health

female runner with knee painAnyone who is familiar with joint healing/pain relief supplements is familiar with glucosamine. Even the US government’s MedlinePlus website says it’s “likely effective for” osteoarthritis based on the research published to date. (13)

The website of one internet celebrity doctor claims this drink is “loaded” with glucosamines. That appears to be a myth, because no published papers have reported finding glucosamine in kombucha.

It is true that for supplemental use, vegan glucosamine is made by fermenting corn or wheat (versus deriving it from shellfish) but there’s no data showing that the kombucha tea fermentation makes it. If this drink really does help with arthritis, knee or joint pain, it would have to be for another reason.

Where this rumor started might because of similar sounding compounds which really are inside, but are not glucosamine.

10. Cancer testimonials

Glucaric acid is a sugar acid which comes from D-glucose. This acid is naturally found in high amounts of many foods including apples, oranges, and cruciferous vegetables. Gut flora (i.e. probiotics) and fermented foods also produce it as a byproduct.

While not all glucoronic acid is directly oxidized into glucaric acid, the probability is that a large amount is, given that the act of fermentation is oxidizing substances.

There has been some research which suggests that glucaric acid might reduce cancer cell proliferation, especially those which are hormone-dependent, like prostate and breast cancer. However very little has been published on this topic and none specific to this drink. (10)

Despite that, kombucha cancer benefits are being claimed by bloggers because it contains some glucaric acid. (3) (11)

That’s quite an assumption and if you’re going to make it, then it would only be fair to also tout broccoli, apples, and the plethora of other glucaric acid food sources.

GT Synergy bottleThe founder of GT Kombucha is George Thomas “GT” Dave. He reportedly became interested in the beverage after his mother, Laraine Dave, came down with breast cancer in 1995. In “The Story Behind The Bottle” on the company’s website, the founder says (12):

“I was relieved to find out that her breast cancer had not spread and that the pungent tasting cultured tea that she had been drinking was part of the reason why.”

This drink was the reason why? What proof is there for that claim?

In Laraine’s story, she says:

“I was diagnosed with a rare and aggressive form of breast cancer, known for moving quickly to the lymph nodes and bones, and based on the size of the tumor (almost that of a golf ball) doctors could not even give me a year to live. I was tested again a week later, and to everyone’s surprise, my cancerous cells had not metastasized. My physicians asked me if I was doing anything special. “Drinking Kombucha everyday” I replied…”

The cells not metastasizing that week is definitely NOT proof or evidence that kombucha is good for cancer prevention, nor that it’s a cure.

It has been claimed that Ronald Reagan drank it as part of his regimen for battling stomach cancer, but that’s all heresay, as there’s no documentation or quotes from the former President doing that. The best kombucha brands in terms of popularity don’t infer that Reagan used it for cancer, but many fan sites and even a book on this topic infers or says that he did.

Until there’s more than personal testimonials, it’s highly misleading for people to claim that it has any benefit for cancer. This is a life and death disease and people who have it don’t have time to be misled with false hopes or marketing.

Is kombucha safe?

Even if some of the health advantages are for real, there also are dangers to be aware of. How much kombucha is too much? One serving per day is believed to be safe for most people, but even with that, adverse reactions may occur.

Side effects of kombucha:

  • Stomach ache or cramps
  • Yeast infections
  • Nausea
  • Vomiting
  • Gas and bloating
  • Abnormal bowel movements
  • Diarrhea
  • Alcohol poisoning
  • Metabolic acidosis (excessive acid buildup)
  • Unknown pregnancy safety
  • Unknown breastfeeding safety

Alcohol content

How much alcohol there is in kombucha can range from 0.5% to 3% depending on how long it ferments. The longer the SCOBY ferments, the more alcohol it will produce. However anything above 3% would require additional grains to be added.

Back in the days when people actually knew who Lindsay Lohan was, you may recall the fiasco of her favorite non-alcoholic drink being pulled from Whole Foods stores because actually, it was alcoholic!

GT Kombucha and Whole Foods settled a class-action lawsuit for $8.25 million because of that alleged mislabeling. (16)

More recent testing (2017) evaluated 8 different products from 6 different brand names. Only KeVita unflavored tea was identified by name, while the others were identified by flavor only. The amount of kombucha’s alcohol ranged from 0.11% to 2.18% for these store bought products. (17)

Kombucha Sample Alcohol Percentage
Elderberry flavor 2.18%
Berry flavor 0.11%
Raspberry flavor 2.22%
Unflavored 1.56%
Ginger-lemon flavor 1.21%
Apple flavor 1.30%

At most, you’re getting about half as much alcohol as beer. Still though, whether fans want to admit it or not, at least this ethanol component of kombucha is not healthy for your liver.

Does it cause gas and diarrhea?

young woman with nausea holding upset stomachThere are two reasons why after drinking kombucha, you may experience gas and bloating. The first is carbonation. It’s not artificially carbonated in the same way that a soda is, but fermentation of the yeast and bacteria lead to this being a lightly carbonated drink.

Regardless of source, all carbonation can increase farts and burps, as the air has to escape somehow.

The second reason has to do with probiotics. Again, you can’t blame the beverage on this, as any source of probiotics can do this. Especially when you first start using them.

These things make some people feel sick, but for most, if the side effect is even noticeable, it will dissipate over time with regular consumption.

Is kombucha safe for a Candida diet? Probably not, as avoiding all sources of yeast is generally recommended.

Is it good for irritable bowel syndrome (IBS) and Crohn’s disease? That probably isn’t safe or ideal, either. Just the carbonation and caffeine alone can trigger adverse reactions in many and as with Candida sufferers, the probiotics and yeasts can further upset the GI tract.

In short, you should consult your doctor before drinking this if you have any sort of GI motility issue.

Dangerous during pregnancy

Why is kombucha bad during pregnancy? There are three possible reasons why.

1. Pregnant women have not yet been studied

Not only has kombucha never been directly studied during pregnancy, but there is not even a post hoc analysis to evaluate birth defects, miscarriages, and so forth and whether or not those rates differ for mothers who drank this during the first, second, or third trimester.

2. Contains alcohol

pregnancy warning on GT Kombucha bottle
This is the warning you will find on a bottle of GT.

You may have heard that it’s okay to have one beer or glass of wine while you have a baby in the womb.

One drink at a time might not be enough to cause Fetal Alcohol Syndrome (FASD), but regardless, alcohol alters the levels of neurotransmitters in the brain of all humans, regardless of their age. That can’t possibly be good for your fragile developing baby.

To measure the potential damage that minor alcohol consumption may cause is currently impossible, since only major abnormalities like FASD and mental retardation can be detected after birth.

But just because you can’t detect potential side effects, all you have to do is consider the facts of what alcohol does to the adult brain to conclude it’s bad for babies and children to be exposed to it.

For the same reason, you should also forgot sipping that Synergy Kombucha while breastfeeding! You don’t want to risk the infant being exposed to any alcohol which might end up in the breast milk.

3. Contains caffeine

Among the three infant risks, this is probably the least concerning, since the caffeine content in the fermented tea is generally quite low.

200 mg of caffeine per day or less is currently recommended by the American College of Obstetricians and Gynecologists (ACOG). Not even a serving of matcha green tea is likely reach that, but any coffee drinker can easily exceed that limit with just a morning cup of Joe.

Is kombucha acidic?

This may be the strongest argument against even healthy adults drinking it daily. When making it homemade, pH test strips for kombucha are used to help determine when it’s ready. The “ideal range” according to Kombucha Kamp is somewhere between 2.5 to 3.5 on the pH scale. This is largely due to the acetic acid created by the bacteria during fermentation.

While it will vary by recipe, here’s how its typical pH compares to other beverages…

bar graph showing pH of kombucha, soda, Coke, coffee and water

That’s right, when it comes to the decay of tooth enamel from acid, you’re not much better off drinking it versus a Coke or Pepsi.

How does kombucha compare to apple cider vinegar? The latter has been found to range from 3.1 to 5. Even though it’s acidic, unlike other vinegars, it has been reported to have an alkalizing effect on the body. For more details, see Patricia Bragg’s Miracle Health System.

Now ACV is still dangerous to your teeth, which is why you should never drink it straight. But people are drinking kombucha straight. Just like with soda, that acidic exposure might erode away the surfaces of your teeth over time. Especially if you drink it everyday for years on end.

Its sugar content is a tiny fraction of a Coke or 7 Up. At least that aspect is healthy for you.

Too acidic for the body?

Aside from being terrible for your teeth, you also don’t know if the acid is good for your body.

The fact that it is an acid is not the problem, since acidic foods can have an alkaline effect after digestion. Fruits and vegetables are good examples of this.

There is not good medical evidence that kombucha is alkalizing in the body. It might be, but we cannot find any scientific evidence of that theory.

What has been reported though is the opposite; metabolic acidosis. That’s where you have too much acid in your body.

A case-study out of Cedars-Sinai Hospital in Los Angeles documents a 22 year-old man with HIV who experienced high levels of lactate and creatinine within 12 hours after drinking the tea. His temperature reached 103° F. The doctors notate that: (17)

“Several case reports exist of serious, and sometimes fatal, hepatic dysfunction and lactic acidosis within close proximity to ingestion.”

Is kombucha an alkaline drink? That quote sure doesn’t lend support for that benefit!

One side effect that is exaggerated is that it can kill you. “Death” is listed under the safety information for the drink on WebMD, but it appears they are basing that off of a 20+ year-old CDC report about one case of death and one case of severe illness. Those occurred in a rural Iowa town after people drank what the CDC called kombucha mushroom tea (yes, it was that long ago, when people still called it mushroom tea).

metabolic acidosis symptoms listAfter drinking approximately 4 ounces per day for 2 months straight, a 59 year-old woman was found unconscious by her neighbor and diagnosis revealed severe metabolic acidosis; her blood’s pH was 6.9 instead of the normal 7.37 to 7.43. She eventually suffered cardiac arrest and died. (18)

A similar episode happened nine days later in the same town with a 48 year-old woman. She too had severe acidosis and suffered cardiac arrest, but was able to be resuscitated.

It turns out this 2nd person was also drinking the tea and she had obtained it from the lady who died.

Of the 21 people in the town who reported drinking kombucha, only one of them was purchasing it for sale at a store/commercial supplier. The others were using homemade kombucha which likely is the culprit, as other pathogenic organisms may have multiplied during fermentation.

This is a reason why making it yourself can be dangerous. You don’t have access to the same safety testing methods that the big commercial brands do.


Sure, kombucha is vegan, gluten free, and non-GMO. But that doesn’t mean it’s good for you!

There may be benefits associated with the probiotic content, but there’s no evidence that getting them from this drink offers additional advantages versus other sources.

However there is evidence that kombucha may be unsafe for your body and bad for your teeth.

Spending $4+ per day on a bottle will cost you nearly $1,500 per year. To add insult to financial injury, most of the probiotics you’re getting might only be the Gluconacetobacter strain (remember this represented around 90% in the tested samples). You’re better off just getting a good probiotic supplement.

We recommend the Hyperbiotics brand of PRO-15 time release pearls available on Amazon.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.