Can fermented food products and pickled vegetables be replaced with probiotic supplements?

In the past, the health benefits of acidified and fermented products were not known, which is why people primarily used acidification and fermentation to extend the shelf life and improve the taste of food. Over 100 years ago, Russian microbiologist Ilja Miecznikow proposed a theory that health can be improved and aging delayed by manipulating the gut microbiota with the friendly bacteria found in yogurt (P. A. Mackowiak 2013). Acidified and fermented products have become an important nutritional component in various food cultures, and in time, they have been linked to evidence of health benefits of food products such as iron and fertilizers. The fermentation process can be applied to many foods. The most commonly available products on the market are yogurt, kefir, milk, cheese, sauerkraut, pickles, and tempeh, natto, miso, kimchi, or kombucha. The most widely studied fermented food is kefir, and scientific evidence suggests its beneficial effect on improving lactose digestion (due to the enzyme beta-galactosidase produced by lactic acid bacteria) and supporting the treatment of Helicobacter pylori infection. Fermented dairy products have positive effects on blood pressure, cholesterol levels, and infection control (K. Ohsawa et al. 2015; V. K. Shiby, H. N. Mishra 2013). The fermentation process usually takes place in the presence of fungi or bacteria. During this process, microorganisms produce a variety of compounds: organic acids, carbon dioxide, diacetyl, hydrogen peroxide, phenyloctanoic acid, bacteriocins, and peptides. The process aims to extend the shelf life of fruits, vegetables, meat, and fish. In addition, it plays a significant role in food preservation by creating metabolites that can inhibit the growth of pathogenic or spoilage bacteria (such as lactic acid, acetic acid, formic acid, propionic acid, ethanol, carbon dioxide, diacetyl, reuterin, bacteriocins, and others). The beneficial effect of fermentation also lies in reducing the content of antinutrients in the product, such as phytic acid and protease inhibitors. However, there are very limited clinical evidence supporting the effectiveness of acidified and fermented foods on the digestive tract. Given the convincing results of in vitro studies, the need for high-quality clinical studies to investigate the health benefits of acidified and fermented foods seems justified (E. Dimidi et al. 2019).

According to the FAO/WHO definition, live microorganisms, given in appropriate quantities, have a positive impact on the host organism. Probiotic strains registered as probiotics must meet specific functional and technological conditions. These strains should primarily come from the human microbiome and have a specific affinity for the type and species that have been confirmed using molecular biology methods. Probiotics must not exhibit pathogenic, invasive, or antibacterial effects on the human body. Clinical studies confirm the positive effect of probiotics on many diseases, including gastrointestinal diseases and allergic diseases.

Fermented foods and yogurt often contain probiotic bacteria, but unfortunately they do not meet the same qualitative and quantitative criteria as preparations. They do not show the same effectiveness and, above all, the same safety of use that is characteristic of products registered as probiotics. On the market, available preparations contain a specific bacterial strain - a specific genus and species (e.g. Lactobacillus plantarum 299v). Unlike probiotic preparations, the bacteria present in fermented products do not have the ability to colonize the mucosa over time, and their metabolic activity in the digestive tract is short-lived. The health properties of probiotics are specific to a given strain. Each contains a specific amount of live bacteria that show proven effectiveness until the expiration date of the preparation. Often, in fermented and cultured products, there are no live bacteria or they are present in much smaller amounts and do not survive the gastrointestinal passage. We cannot expect yogurt or cultured products to restore the gut flora, e.g. during the prevention of unwanted side effects of antibiotic therapy. The process of probiotic supplementation often lasts several weeks or even months, and the repetition of the dose in probiotic therapy is very important.

Fermented products and pickles have health-promoting properties and are undoubtedly worth incorporating into the diet, primarily due to their high lactic acid content and the presence of vitamins and minerals. However, fermented food does not substitute probiotic preparations available in pharmacies that possess specific properties verified by research. In this way, we can be certain of the strain type we will consume and if it will be resistant to stomach acid or bile, which will enable the bacteria to endure the gastrointestinal passage and generate the desired health effect.