What Are the Health Benefits of Kombucha and Fermented Drinks?

From kimchi and sauerkraut to yogurt and tempeh, fermented foods and drinks have existed for centuries in cultures around the world. Fermentation began as a way to preserve food and keep it safe. But, more and more, research is showing fermented foods come with certain health benefits, like improved gut health and lowered risk of heart disease. 

Recently, kombucha and other fermented drinks have become especially popular, partly because of the many health claims surrounding them. But is kombucha actually good for you, and is it safe to drink?

What is fermentation?

Fermentation is a natural process in which certain organisms, like bacteria and yeasts, convert raw food into different substances that help preserve the food and keep harmful organisms from growing. 

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Robert Hutkins, a fermentation expert and professor of food science at the University of Nebraska, spoke with GoodRx on the topic of fermentation. He explained that food spoilage and fermentation are similar processes, but that fermentation results in products that we want. 

In addition to food preservation, Hutkins highlighted other possible benefits of fermentation, such as adding vitamins and probiotics to food. Studies also show that people who eat certain fermented foods may have a lower risk of developing diabetes, heart disease, and obesity.

What are kombucha and other fermented drinks made from?

Fermented tea — which we now call kombucha — and other fermented drinks have been around for thousands of years. Kombucha is usually made from:

• Brewed black tea

• Sugar

• An active kombucha culture, or SCOBY (symbiotic colony/culture of bacteria and yeast), which contains different types of yeasts and bacteria 

As the popularity of kombucha continues to grow, there are many variations on this basic recipe available to consumers.

In addition to kombucha, there are many popular fermented drinks made from other raw foods, like kefir, which comes from milk.

Is kombucha good for you?

There are many claims about the health benefits of kombucha, including that drinking it improves gut health, metabolism, and immunity. But are they true?

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As it turns out, there isn’t solid data that backs up these claims. Much of the evidence that supports kombucha’s benefits comes from animal studies or from evaluating the beverage’s individual components. So what's being studied isn't necessarily the same kombucha you drink from a bottle.

Keep in mind that this doesn’t mean kombucha isn’t healthy. Rather, it means more research is needed. Fortunately, there are some promising studies on kombucha’s health benefits currently underway. 

For most people, there is nothing wrong with drinking kombucha, especially if they enjoy it. But, if you’re looking for proven health benefits, “don’t believe all the hype,” as Hutkins put it.

Are there any benefits to kombucha?

While we don’t have studies proving its health benefits, kombucha has been found to contain these potentially healthy ingredients: 

• Polyphenols: These plant compounds have been associated with a decreased risk of some cancers, heart disease, and diabetes.

• Vitamins: This includes vitamin B12, which helps keep your nerves and blood cells healthy, and vitamin C, which supports a healthy immune system.  

• Minerals: This includes copper, which supports your nerves and immune system, and zinc, another immune-system booster.  

• Antioxidants: These compounds help prevent or delay some types of cell damage.

• Prebiotics: These carbohydrates can help good bacteria grow in your gut. 

What fermented drinks are good for you?

There have actually been many studies on other fermented drinks that show evidence of possible health benefits. “The data for cultured dairy products far exceeds that for any other category,” Hutkins said.

Consuming kefir and fermented milk products, like yogurt, has been associated with:

• Reduced risk of certain cancers (like breast and colon)

• Improved weight maintenance

• Decreased risk of Type 2 diabetes and cardiovascular disease

• Improved gut health and reduced symptoms of irritable bowel disease

Is kombucha safe?

There have been some safety concerns raised about kombucha, including the risk of contamination and toxicity. Brian Nummer, a food microbiologist at Utah State University who studies food safety, spoke to GoodRx about these concerns.

Kombucha is often made at home and, as Nummer pointed out, there is no government regulation when dealing with consumer-made products. So it’s important that people are informed about the possible risks. “One of the things that we do is to educate consumers on things that could harm them,” Nummer said about his work in food safety.

When kombucha is made correctly, it is safe to drink. But there are a few things to keep in mind, especially if you’re brewing at home. To make kombucha safely at home, Nummer recommends:

• Starting with a store-bought SCOBY, so that you know what you’re getting 

• Sticking to raw kombucha instead of adding things like fruit juice, which will make it less acidic 

• “Back-slopping,” or using the SCOBY from your previous batch to make the next one

Can kombucha be bad for you?

If kombucha isn’t made correctly, it can cause some potentially serious health problems. So if you drink homemade kombucha, make sure you know how it was produced. 

It’s also important to note that many commercial kombuchas are not pasteurized and require refrigeration. If you want to make sure kombucha is safe, make sure it’s pasteurized. Being careful about what kombucha you drink will help you avoid the potential health risks, which we discuss below. 

Contaminants

The acidity of kombucha is very important. The acid in kombucha kills potentially harmful pathogens and prevents conditions like botulism, a rare but serious illness caused by a bacterial toxin that can be found in home-canned foods.

The acidity of a food is measured on the pH scale. Nummer explained that raw kombucha has a pH of about 2.8, which means that it’s pretty acidic. (For reference, lemon juice has a pH of about 2.0 to 2.6).  

When different products are added to enhance raw kombucha — like fruits and juices — they can make it less acidic. And that could mean that pathogens in the kombucha don’t get killed, Nummer pointed out.

Toxicities 

There have been reports of lead poisoning associated with kombucha, likely due to the type of container that was used for brewing. Metal and stainless steel containers can react with the acid in kombucha, causing lead to seep into the drink. Using a container that is approved for home fermentation can help prevent this issue.

Added sugar

Although they’re marketed as healthy drinks, many store-bought varieties of kombucha have a lot of added sugar. This sugar is added for taste after the fermentation process, during which the SCOBY feeds on the sugar in tea. So if you’re watching your sugar intake, check the nutrition label of kombucha carefully.

Are there any side effects of drinking kombucha?

People have reported having symptoms after drinking kombucha. These symptoms include::

• Dizziness

• Nausea and vomiting

• Head and neck pain

• Allergic reactions

These effects may be from kombucha that wasn’t made properly. But if you’re trying kombucha for the first time, it’s a good idea to try a small amount first and see how you do. 

Who shouldn’t have kombucha or fermented drinks?

Because kombucha contains low levels of alcohol and caffeine and because it may not be pasteurized — which can be unsafe, especially without refrigeration — it is generally not recommended for:

• People who are pregnant or breastfeeding 

• People with lower immunity, such as people with HIV

• Children

People who have heartburn or acid reflux may also want to limit their intake of kombucha, since it is acidic. If you have any specific health concerns or questions about kombucha, talk to your healthcare provider for more information.

Why trust our experts?

Written by:

Maria Robinson, MD, MBA

Maria Robinson, MD, MBA, is a board-certified dermatologist and dermatopathologist who has practiced dermatology and dermatopathology for over 10 years across private practice, academic, and telehealth settings. She is a fellow of the American Academy of Dermatology and the American Society of Dermatopathology.

Edited by:

Samvida Patel, MNSP, INHC

Samvida Patel, MNSP, INHC, is a health editor at GoodRx. She is a nutritionist and integrative nutrition health coach with over 8 years of experience in health communications.

Reviewed by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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