I particularly wanted to look at this article as it is often quoted as evidence that kombucha is dangerous and shouldn’t be recommended as a health food. I think it is worth having a closer look at what it is actually saying so we can make up our own minds about it.
For the full text of today’s paper, follow the link:
Probable Gastrointestinal Toxicity of Kombucha Tea – Is this beverage healthy or harmful? by Radhika Srinavasan and colleagues, J Gen Intern Med, 1997
Key Take home points
- This paper is about four people who were admitted to hospital with distressing symptoms after drinking kombucha. It does seem that their kombucha was to blame for their symptoms.
- Be careful about contamination and make sure you are brewing your kombucha in glass, not in ceramic or lead crystal.
- Any substance that has an effect on the body can have unpredictable results. Just because a food or drink is generally safe, there is no guarantee that you personally will have no ill effects. Think of how many people you know who have had a bad reaction to seafood, for instance.
Background information for this study:
These researchers are presenting their findings from four patient case-studies. The four patients each presented at the hospital with a variety of symptoms, and in each case kombucha was settled upon as the likely probable cause of their symptoms.
This paper was published in 1997, when very little verifiable research had been conducted into kombucha and its effects.
What the researchers already knew:
Kombucha use was popular as a tonic for a wide variety of ailments, none of which had yet been proven.
Popular (non-scientific) literature referred to the “kombucha retch factor” when consuming more than 4oz per day (about half a cup).
What these researchers were investigating in this study:
Basically, they were looking for a probable cause of the symptoms experienced by these patients. They were also looking for some indication of how common these symptoms are among kombucha drinkers.
- This patient had a history of heavy alcohol consumption. She presented with jaundice and other symptoms that her liver was under severe stress.
- She had been drinking kombucha for 2 months when the jaundice began. When she noticed her jaundice, she stopped drinking kombucha, but 6 weeks later was still showing symptoms and went to the hospital. Examination showed abnormal liver function results, but ruled out all the usual suspects, including alcoholic liver disease. A further 7 weeks later, her laboratory results had returned to normal.
- This patient had symptoms of dry mouth, dizziness, nausea, vomiting, headache and neck pain. She had been drinking half a glass of kombucha every day for several months. She was treated for symptoms and released. When she drank kombucha again, the symptoms reappeared and she went back to hospital, where she also fainted three times. The only significant blood test result was a very high caffeine level (about twice what you’d expect from normal coffee consumption). Her scoby was examined and found to contain caffeine but no other suspicious ingredients.
Patients 3 and 4
- Both patients presented with symptoms consistent with an allergic reaction shortly after consuming kombucha. They were treated for allergy and discharged.
What they did:
The researchers looked at scientific literature to explain what they saw in these patients, but conducted no experiments themselves. Patient 2 had retested herself with kombucha and confirmed that her symptoms returned when she drank it. They considered it unethical, given their symptoms, to ask the other patients to re-challenge themselves with kombucha.
What they found:
Looking at published research, they found three studies, describing a total of four examples of people with bad reactions to kombucha, two involving abnormal liver function, and two of severe metabolic acidosis (where the body gets too acidic, causing heart failure and neurological symptoms). Of the two women with metabolic acidosis, one recovered while the other died.
One study had traced other kombucha drinkers using scobys from the same source as the women with metabolic acidosis. They found 115 other people, none of whom showed ill effects.
The researchers noted that the FDA had found no disease-causing bacteria or hygiene violations in commercial producers. They speculated that home-brewed versions might be more susceptible to contamination, and noted that a 1995 survey of home-brewed scobys had found contamination by Penicillium and Candida yeasts in three of the tested scobys.
They pointed out that when the tea is made properly, it should be highly acidic, and so most disease-causing organisms would not survive in it. But that high acidity also means it should not be brewed or stored in ceramic or lead crystal vessels, as heavy metals can leach into the tea.
They conclude their paper by saying that a half glass of kombucha is likely to be perfectly safe for most people, but that potential health risks are unknown for people drinking more than that, or for those with underlying health conditions.
So what does that mean for us?
For two of these patients, the problem seems to have been a previously unknown allergy.
But because the exact causes of the other patients’ symptoms couldn’t be pin-pointed, we are left with the researchers’ speculations as to the causes. It might be contamination, it might be heavy metal poisoning, or it might be some other unknown aspect of kombucha coming into play for these individuals. It might be pesticide residue on their tea leaves. It might even have been nothing to do with the kombucha at all. We just don’t know.
Regarding the liver failure cases, it happens that just this week I saw a news report of a young woman having liver failure due to drinking 3 cups of green tea per day, which highlights that sometimes even the most innocuous substance can cause problems. Of course, kombucha is made from tea, so the liver failure is perhaps even caused by the same thing.
When trying something new be sensible and cautious – especially if you expect it to have some effect on your body or if you have underlying health conditions. Be doubly cautious if you have a history of allergy to mold, yeast, penicillin etc.
Just because something is good in small doses there is no guarantee that it will be good in large doses. Harald Tietze, one of the early authorities on kombucha, recommended a standard dosage of half a cup, and taking a rest from it about 1 week in 4. He did also note that he drank 1 to 2 litres per day for 6 weeks to test for ill effects and felt none, so ymmv, as they say.
If you do have any strange symptoms, stop drinking kombucha and go get checked out.
One other thing:
Sometimes when you start taking a probiotic you can have an upset tummy for a while as your system gets used to the new microbes. If this happens to you when you drink kombucha, start with only a small amount each day and work your way up to a half glass. If your symptoms last for what feels like too long, then stop drinking it. I’d probably stick it out for a week before deciding to stop, but that’s just my gut feeling – there is no science to support that as far as I know 🙂 There are plenty of other probiotic foods and drinks for you to try instead!
NOTE: No part of this site constitutes medical opinion or advice. Please see your doctor for all health concerns
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