UNC Health Care
A photograph of jars with pickled vegetables.

4 Reasons to Eat Fermented Food

Fermented foods have been consumed throughout time and across cultures. What started thousands of years ago as a means to preserve food is now understood to help balance the good and bad bacteria in the gut—a key to good health. 

Andrea Azcarate-Peril, PhD, is the director of UNC School of Medicine’s Microbiome Core and an expert on the gut microbiome. 

“A fermented food is a food product that has gone through the process of fermentation, and as a result, has different characteristics from its original form,” Dr. Azcarate-Peril says. 

Fermentation is the chemical breakdown of a substance—say milk, cucumbers or cabbage—by microorganisms like bacteria and yeast that turn them into yogurt, pickles and sauerkraut. (Beer and wine are fermented products, but they don’t have the same positive effect on the gut because of their alcohol content.) 

Here are four reasons Dr. Azcarate-Peril says fermented foods should be part of your diet.

1. Fermented foods can prevent bad bacteria from growing in your gut. 

You might say a yogurt a day keeps the bad gut bacteria away. Fermented foods like yogurt, kefir and sour pickles have lactic acid bacteria in them as a result of the fermentation process. Lactic acid bacteria are a type of good bacteria that lower the pH level of whatever environment it lives in, making it less hospitable for bad bacteria—the stuff found on kitchen sponges, raw poultry and toilet seats. Having a lower pH in your gut means that if and when you do consume sickness-causing bacteria, it won’t be as likely to make you ill. 

2. Fermented foods can prevent bad bacteria from attaching to your gut. 

Not only does lactic acid bacteria lower the pH of your gut to prevent bad bacteria from growing, it also prevents bad bacteria from attaching to the walls of your gastrointestinal tract. Lactic acid bacteria compete with bad bacteria, such as E. coli, for space. The battle is called competitive exclusion, and it prevents the bad bacteria that does get into your gut from staying there. If it can’t attach to the walls of your gut, it gets passed through your digestive system and out of your body.

3. Fermented foods deliver more probiotics to your body. 

“Not all fermented foods have probiotics in them, but many of them do, which is another reason why eating them is good for you,” Dr. Azcarate-Peril says.

Probiotics can help your body in multiple ways: They help alleviate gastrointestinal symptoms, prevent viral infections, and decrease anxiety and stress levels. Some fermented foods that include probiotics are yogurt, sauerkraut, kimchi, miso and kombucha. Probiotics are important in maintaining a balanced gut microbiota—the balance between good and bad bacteria—especially during periods of life when the balance is most fragile, which includes childhood and later years. 

4. Fermented foods may reduce the risk of developing colon cancer. 

“The research we’ve seen leads us to believe that eating more fermented foods helps lower chances of developing colon cancer,” Dr. Azcarate-Peril says.

That’s because consumption of fermented foods results in increased intestinal butyrate, a short-chain fatty acid that is essential in feeding the cells that line your digestive tract, which keeps them healthy. Butyrate also prevents toxins from damaging your colon and helps your system cleanse itself of those toxins.

Dr. Azcarate-Peril says one serving of fermented foods a day can help keep you healthy. She also says to be conscientious about which fermented food items you choose to incorporate into your diet. When looking for a good yogurt to buy, make sure it is low in added sugar and the ingredient label says “live active bacteria.” 

Also, it’s important to know that not all pickled foods have been through the fermentation process. Look on the label for “fermented” or “probiotics” to be sure the fermented food you are choosing is the best choice for your gut health.


Learn three simple ways to enjoy fermented foods.