By Annette Pinder

According to the National Library of Medicine, fermented foods have become popular due to their potential health benefits, especially for digestion and gut health. From yogurt and kefir to sauerkraut, kimchi, miso, and kombucha, these foods have been part of traditional diets worldwide for centuries. But are fermented foods truly healthy for everyone? The answer is yes for most people—when eaten thoughtfully and in moderation.

What is fermentation?

Fermentation is a natural process in which microorganisms, such as bacteria or yeast, break down sugars and starches in food. This process helps preserve food, enhances flavor, and can improve nutritional value. In many cases, fermentation produces beneficial bacteria known as probiotics, which support the gut microbiome—the diverse community of microorganisms living in the digestive tract.

One of the most well-known benefits of fermented foods is their ability to support gut health.

Foods that contain live and active cultures may help increase microbial diversity in the gut, which is associated with improved digestion, better immune function, and reduced inflammation, according to Stanford Medicine and Harvard Health. According to Verywell Health, a healthy gut microbiome has also been linked to improved metabolic health and even mood.

Fermented foods may also make digestion easier.

The fermentation process partially “pre-digests” food, breaking down compounds that can be difficult for some people to tolerate. For example, fermentation reduces lactose in dairy products, which is why yogurt and kefir are often better tolerated by people with mild lactose intolerance. Another benefit is improved nutrient availability. Fermentation can increase levels of certain vitamins, including B vitamins and vitamin K2, and can improve the absorption of minerals such as iron and magnesium. These nutrients play important roles in energy production, bone health, and cardiovascular health.

Although fermented foods offer benefits, they are not a one-size-fits-all solution.

Not all contain live probiotics. Products like shelf-stable pickles or pasteurized sauerkraut may be heat-treated, which kills beneficial bacteria. Checking labels for “live and active cultures” is important. Some people may also experience side effects, especially when consuming large amounts. Bloating, gas, or digestive discomfort can happen, particularly for those with irritable bowel syndrome (IBS), small intestinal bacterial overgrowth (SIBO), or histamine intolerance. In such cases, gradually introducing fermented foods—or avoiding certain types—might be necessary. It’s also important to note that some fermented foods are high in sodium or added sugars. Kimchi, sauerkraut, and miso can be rich in sodium, while kombucha might contain added sugars. Moderation and portion control are essential.

Fermented foods can be a healthy and flavorful part of a balanced diet, offering benefits for gut health, digestion, and nutrient absorption. However, they are not a cure-all. Small, regular servings—often just one or two portions a day—are enough to gain potential benefits without overwhelming the digestive system. As with any dietary change, listening to your body and choosing minimally processed options is the best approach.