Kombucha: Everything You Need to Know

Kombucha is a fermented beverage that may offer health benefits.

Kombucha is made by mixing tea, sugar, and probiotics together and then letting the mixture ferment for one to two weeks. During the fermentation process, various bioactive substances are formed. These substances are thought to account for the purported health benefits of kombucha. Small amounts of caffeine and alcohol may also be present.

Components of kombucha have also been linked to anti-inflammatory, antidiabetic, and antimicrobial effects, among others.

Green, black, or oolong tea is typically used to make kombucha. The probiotics used to make kombucha are known as SCOBY, which stands for "symbiotic culture of bacteria and yeasts." Various probiotic strains may be used.

There are many methods for making kombucha. The type of tea used and how long the drink is fermented is thought to have a significant impact on the potential health benefits of the final kombucha product.

This article will discuss the scientific evidence supporting the uses of kombucha. It will also examine any side effects, precautions, drug interactions, and other things you should know about kombucha.

Uses of Kombucha

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease. 

Kombucha has been found to contain beneficial active ingredients, including polyphenols, flavonoids, and catechins. These and other active substances act as antioxidants.

Preliminary research has shown that kombucha possesses various properties that may benefit human health. According to one review, these properties include:

• Antioxidant
• Anti-inflammatory
• Antimicrobial
• Antihypertensive
• Anti-aging
• Anticancer
• Neuroprotective (brain protective)
• Wound healing
• Antidiabetic
• Hepatoprotective (liver protective)
• Antihypercholesterolemic (high cholesterol)

However, the recipe for making kombucha has not been standardized. This means that the potential health benefits may vary from one kombucha product to the next.

Nevertheless, kombucha continues to be researched for its potential health benefits. Following is a look at some of the popular uses of kombucha.

Gut Health

Fermented foods and beverages contain probiotics, or "good" bacteria, that can help improve the health of your gut.

As a fermented beverage, kombucha has been found to reduce gut dysbiosis, or an imbalance of the gut microbiome.

In one study, rats were fed a standard diet or a high-fat, high-fructose diet for eight weeks before receiving kombucha (made with either green tea or black tea) for 10 weeks. After the first eight weeks, the high-fat, high-fructose diet was found to cause metabolic changes in the rats, which included an increase in gut dysbiosis.

At the end of the study, both types of kombucha were associated with improvements in the gut microbiome of the rats fed the high-fat, high-fructose diet, which was thought to be caused by the various phenolic compounds in the fermented drinks.

Unfortunately, human trials on this topic are limited. While many people assume that kombucha improves gut health, this has yet to be proven through solid scientific evidence.

Bacterial Infections

Many people use kombucha for its supposed antibacterial properties.

Some research has found kombucha to be effective against various bacteria strains, such as Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Klebsiella pneumonia.

Researchers from one in vitro (lab) study compared the effects of various forms of black tea kombucha (fermented, unfermented, neutralized, and heat-treated) on a number of bacteria. The fermented kombucha showed the most effects against the bacteria. Fermented kombucha was also found to inhibit E. coli and Staphylococcus aureus more than the other kombuchas.

Multiple compounds, including acetic acid and catechins, are thought to be responsible for kombucha's possible antibacterial activity.

Studies need to be performed on humans to confirm and strengthen these claims.

Hypoglycemic Effects

Kombucha is thought to have a hypoglycemic (blood sugar–lowering) effect, but the research supporting this theory is weak.

In one study, mice were induced with type 2 diabetes via diet and medications and then given green tea kombucha for four weeks. Next, the researchers performed fecal studies and found that kombucha intake positively altered the gut microbiome, leading to decreased inflammation and insulin resistance in the mice. Kombucha intake was also associated with an increase in short-chain fatty acids (SCFA) in subjects, which promoted the secretion of hormones needed to lower blood sugar.

Another study was performed on 11 healthy adults in which participants ate a high-glycemic meal (containing foods high in carbohydrates that cause a rapid increase in blood glucose) with either soda water (the control), diet lemonade, or unpasteurized kombucha.

Compared to the other two beverages, kombucha showed a greater impact on post-meal blood sugar. The study participants who drank kombucha had significant reductions in blood sugar and insulin after their meal.

More vigorous, well-designed studies are needed to support using kombucha for type 2 diabetes.

High Cholesterol

Substances found in kombucha have been shown to exhibit cholesterol-lowering effects in lab and animal studies.

A study performed on rabbits found a link between kombucha consumption and lower cholesterol levels. In the study, rabbits were divided into four groups; normal diet, high-cholesterol diet, normal diet plus kombucha, or high-cholesterol diet plus kombucha. After 40 days, blood cholesterol was significantly reduced in the rabbits who received kombucha.

Other studies have found similar results, with research pointing to kombucha's ability to decrease both triglycerides and low-density lipoprotein (LDL) cholesterol (considered "bad" cholesterol) in various animal models.

At this time, most studies on kombucha for high cholesterol have been performed on animals rather than humans. Until human trials are successfully completed, kombucha cannot be recommended as a treatment for high cholesterol.

Liver Health

Kombucha has been touted as a natural remedy for liver protection, with some going as far as to say that the fermented tea has a detoxifying effect.

While liver detoxification effects have not been proven regarding kombucha, it may offer some form of protection for the liver (hepatoprotection).

In a mouse model study, kombucha showed hepatoprotective effects by lowering both liver enzymes and fat accumulation in the liver. The study also revealed that mice given kombucha had less inflammation and liver scarring than mice who did not receive kombucha. While researchers from the study didn't believe kombucha could cure liver disease, they felt that it could at least stabilize liver disease in some cases.

More research is needed on the potential role of kombucha in liver health.

What Are the Side Effects of Kombucha?

Kombucha is generally considered safe. But consuming kombucha may come with potential side effects that could be mild or severe.

Common Side Effects

The safety of kombucha has been questioned because it contains live, active bacteria cultures (probiotics). Some researchers worry that using the wrong probiotics, incorrectly fermenting kombucha, or preparing kombucha in unclean conditions may make side effects more likely. Reported side effects of kombucha include:

• Dizziness
• Headache
• Allergic reaction
• Upset stomach

In general, kombucha is only thought to cause side effects if it was incorrectly prepared or if the person drinking it has a weakened immune system.

Severe Side Effects

Although extremely rare, kombucha has been linked to severe side effects. In most cases, severe side effects were noted due to overconsumption or consuming improperly prepared homemade kombucha.

Large-scale studies or reviews have not been performed on kombucha's safety, so much of the information on potential severe side effects is from case reports.

In one case report, a woman who drank 32 ounces of kombucha per day (8 times the recommended amount) plus 10 to 15 ounces of wine for three months developed liver necrosis (death of tissue). Renal (kidney) failure, lactic acidosis, and hepatitis have also been linked to kombucha consumption, but only in rare cases.

For best practice, choose reputable brands and only drink the recommended amount of kombucha.

Precautions

Not enough human research has been done on kombucha to determine whether it is safe for everyone. Some people may need to avoid or limit the consumption of kombucha.

There is some concern that kombucha may cause toxic effects in certain populations due to its acidity and trace amounts of alcohol and caffeine. Therefore, kombucha should be avoided in:

• Infants
• Children under 4 years of age
• People who are pregnant
• People with kidney failure
• People with human immunodeficiency virus (HIV)

It is not clear if kombucha is safe for people who are breastfeeding.

Talk with a healthcare provider if you have a health condition and are wondering if kombucha is safe for you.

Dosage: How Much Kombucha Should I Drink?

The Centers for Disease Control and Prevention (CDC) has declared 4 ounces of kombucha daily to be a safe dose.

Additional dosage guidelines are not available for kombucha. More evidence is needed to determine safe kombucha dosing for various health benefits.

You may notice that many kombucha brands come in bottles and serving sizes much larger than 4 ounces. To be safe and to lower your risk of side effects, stick with four ounces of kombucha daily.

What Happens If I Drink Too Much Kombucha?

It's important to monitor your intake of kombucha, as drinking too much may have consequences.

Typically, adverse events occur if you overconsume kombucha for more than a couple of weeks. Drinking too much kombucha may lead to:

• Liver toxicity
• Allergic reactions
• Nausea
• Vomiting
• Headache
• Jaundice (yellowing of the skin and whites of the eyes)
• Kidney failure
• Lactic acidosis (pH imbalance)

Remember that an intake of just 4 ounces a day of kombucha has been deemed safe.

To avoid toxicity and side effects, only use kombucha as directed.

Kombucha Interactions

As with many herbs and dietary supplements, kombucha may interact with various medications, foods, or supplements.

Kombucha may lower blood sugar, which means people on antidiabetic and other blood sugar–lowering medications may need to avoid using it. If blood sugar gets too low, hypoglycemia may occur. Hypoglycemia may cause fatigue, irritability, heart arrhythmia, headache, and other adverse events.

Other interactions may exist, so talk to a healthcare provider about any medications, herbs, or supplements you take before adding kombucha to your diet.

Carefully read the ingredients list and nutrition facts panel of any kombucha product to know which ingredients and how much of each ingredient is included. It's advised that you review the nutrition label with a healthcare provider to discuss any potential interactions with foods, other supplements, and medications. 

How to Store Kombucha

For quality purposes, it's important to store kombucha properly.

Ready-made or homemade kombucha should be stored in the refrigerator. Unrefrigerated kombucha may continue to ferment, which could lead to changes in taste and potential health benefits.

Keep kombucha away from small children, who may accidentally consume too much. Children under 4 years old should not drink kombucha.

Discard kombucha as indicated on the packaging or once it expires. Kombucha may be safe to drink for up to four months, but after that time it may lose its potency and flavor.

Similar Products

Various dietary supplements and products may work similarly to kombucha. These include:

• Probiotics: Regarding gut health, probiotic supplements (like capsules, gummies, powders, etc.) are another potential option. Although research is mixed on the use of probiotic supplements for gut health, there is some evidence that certain probiotic strains positively change the gut microbiome. Like kombucha, however, probiotics may not be appropriate for everyone, including those who are immunocompromised.
• Ginger: Active ingredients in ginger, like gingerol, are thought to provide antibacterial effects. Lab studies have shown that ginger helps prevent the growth of bacteria. In particular, ginger exhibits antibacterial activity against E. coli, Salmonella typhi, and Bacillus subtilis.
• Artichoke extract: The extract from artichokes may benefit people with high cholesterol. According to one review of nine trials, using artichoke extract has been associated with significant reductions in total cholesterol, LDL cholesterol, and triglycerides.
• Dandelion: Similar to kombucha, some studies have examined dandelion's effects on the liver. In one animal study, dandelion was found to decrease fat accumulation in the livers of mice. This may help prevent nonalcoholic fatty liver disease (NAFLD).

Many healthcare providers recommend taking just one supplement at a time for a health condition. Talk with a healthcare provider to learn which supplement may be best for you.

What to Look For When Choosing Kombucha

Besides beverages, other forms of kombucha are available.

Kombucha drinks are probably the most popular option, but you can also find kombucha as a powder or capsule supplement. However, there isn't solid scientific evidence behind these other supplement forms, as most studies have been performed on kombucha beverages.

Most kombucha brands are naturally vegan and gluten-free. Organic options are also available. Read the product label to ensure the kombucha you choose fits your dietary preferences.

It's important to understand that kombucha is largely unregulated. In fact, some believe that products should be standardized to improve both the safety and efficacy of kombucha as a whole.

Typically, kombucha products are not tested by third parties for quality or truth in advertising. It's best to buy kombucha from reputable brands and understand that the ingredients may vary from one product to the next.

If you're making kombucha at home, follow directions closely and take extra measures to keep your work area clean. It's also vital to ferment and store kombucha at proper temperatures.

Summary

Kombucha is a fermented beverage made with tea, sugar, and SCOBY.

It is touted as a natural remedy for many health conditions, including type 2 diabetes, bacterial infections, and high cholesterol. However, scientific evidence on these and other uses of kombucha is weak and more research is needed.

Kombucha may not be right for everyone, and side effects are possible. Talk with a healthcare provider before adding kombucha to your diet to make sure it's a good fit.