What you should know about fermented foods

Fermentation is a process in which natural microorganisms (bacteria and yeast) break down food components, thereby preserving it. Traditional fermented foods are found in many cultures, such as yogurt, kimchi, sauerkraut, Indian idlis and dosas, tempeh, and others. Historically, fermentation was a way to preserve food without refrigeration, and today it is also valued for its potential benefits for the gut microbiome.

The benefits are twofold:

• Pre-digestion of components — microbes “pre-digest” food, changing its composition and making individual substances more accessible.
• Maintaining the balance of the microflora — live bacteria from fermented foods compete with less beneficial microorganisms in the intestines and help maintain the balance of the microbiome.

However, not all fermented foods contain live probiotics. For example, yogurt contains live probiotics, but sourdough bread contains few, as heat treatment kills microorganisms. Moreover, not every product labeled “probiotic” is actually beneficial. Beer and wine are also fermented beverages, but their impact on the microbiome is more negative.

Experts recommend focusing on whole fermented foods, such as yogurt, kefir, kimchi, sauerkraut, tempeh, and fermented vegetables (beets, green beans). When purchasing, look for the label “with live cultures” rather than simply “probiotic,” as the latter is often used for marketing purposes.

Special care should be taken with industrial probiotic versions of sodas, chocolate, and other processed foods, as well as with sugar-containing options. According to gastroenterologist Lisa Ganju (NYU Langone Health), excess sugar feeds unwanted bacteria and negates potential benefits.

The optimal strategy is to regularly and variably include fermented foods in the diet. Nutritionist Dalia Perelman (Stanford University) suggests focusing on two servings per day, while Barbara Olenchock, director of the Center for Applied Nutrition at the University of Massachusetts Medical School, advises combining different categories, such as dairy (yogurt, kefir) and fiber-rich (kimchi, sauerkraut). It is important to note that fermented foods should be part of a balanced diet, as beneficial bacteria require prebiotics and fiber-rich foods.

For most individuals, fermented foods are safe and provide a unique flavor experience. But there are nuances:

• People with a weakened immune system or with irritable bowel syndrome should consult a doctor before actively introducing such products into the menu.
• At first, temporary reactions are possible – bloating, gas and discomfort while the intestine adapts. If the state of health worsens, it is better to reduce the amount or temporarily abandon the product.

The effect of fermented products strongly depends on individual characteristics, what is great for one person, another may not fit. Therefore, the main advice is to proceed gradually, monitor your well-being, drink enough water, and consider these foods as part of a balanced and varied diet, rather than as a magic solution.