What Happens to Your Gut When You Eat One Fermented Food a Day
Key Takeaways
- Eating one fermented food a day introduces live beneficial microbes that can improve digestion, reduce bloating, and support regularity as your microbiome balances out.
- A healthier gut microbiome supports immune function, helps regulate inflammation, and may even positively influence mood over time.
- Fermented foods deliver live bacteria alongside fiber and enzymes, making nutrients more absorbable—often with broader benefits than single-strain probiotic supplements.
Fermented foods have been staples in many traditional diets for centuries, and now they’re gaining attention all around the world for their impact on digestion, immunity, and overall health. But what actually is happening on your plate and in your gut when you add some kimchi or sauerkraut to your meal? We asked nutrition experts.
What Is Fermentation?
Fermentation is a natural process that transforms food through a chemical reaction with beneficial microbes, sometimes referred to as "good bacteria." “A food is considered fermented when bacteria or yeast break down sugars and starches over time, transforming the food and making its nutrients easier for the body to absorb,” says Meena Malhotra, MD, founder of Heal n Cure Medical Wellness Center. This microbial breakdown doesn’t just preserve the food—it completely changes it and enhances it. As fermentation happens, nutrients in the food also become more bio-available.
A registered dietitian notes that this transformation is what distinguishes fermented foods from non-fermented foods. “Fermentation happens when microbes like bacteria or yeast break down sugars and starches, improving digestibility and increasing the bio-availability of certain nutrients,” she says. This makes it easy for the gut to absorb all the beneficial ingredients. “The result is food that naturally supports the gut microbiome.”
One of the biggest ways fermented foods can impact someone’s body is through their relationship with the gut microbiome, which is the complex ecosystem of trillions of bacteria that influence digestion, immune function, inflammation, and sometimes even mood. “One of the biggest benefits of fermented foods is that they introduce live microbes, which help support a healthier, more balanced gut environment,” Dr. Malhotra says.
Unlike probiotic supplements, which typically contain only a few isolated strains, fermented foods deliver millions of live microbes alongside fiber and essential enzymes. “Fermented foods naturally combine fiber, enzymes, and beneficial bacteria, while supplements tend to be more targeted and strain-specific,” Dr. Malhotra adds.
What Happens When You Start Eating Fermented Foods Every Day
For many people, adding just one serving of fermented food per day can lead to noticeable changes in the digestive system. “When people start eating fermented foods regularly, they often notice better digestion, less bloating, and more regular bowel movements within a short period of time,” Dr. Malhotra says. These changes are signs that the microbiome is beginning to shift and regulate.
“Regularly eating fermented foods can help increase microbial diversity, which is one of the most important markers of a healthy gut,” Corwin says. She warns, however, that some people may experience mild discomfort if they’re not used to eating fermented foods. “Some may notice mild bloating as the microbiome adapts,” she says. “But this usually settles as the gut becomes more resilient over time.” Starting with small portions and rotating different fermented foods can help ease this transition. But the results aren’t just short-term: over time, the benefits of regularly eating fermented foods extend well beyond the digestive system. “A more diverse gut microbiome plays a critical role in immunity, inflammation regulation, and even mood,” Dr. Malhotra says.
Common Fermented Foods You’ll Find at the Grocery Store
Fermented foods are fairly easy to find on your trip to the grocery store. “Accessible fermented foods include yogurt with live cultures, kefir, sauerkraut, kimchi,miso, tempeh, and many types of pickles,” Dr. Malhotra suggests.
Corwin encourages shoppers to pay attention to labels and how foods are stored and shelved. “Look for yogurt or kefir that lists the bacterial strains on the label, and choose refrigerated sauerkraut or kimchi, which are more likely to contain live cultures,” she says. Other simple and easy-to-find options include kombucha and pickles that are fermented rather than vinegar-brined.