FORUM   

Medicina dello Sport 2021 March;74(1):175-96

DOI: 10.23736/S0025-7826.21.03903-X

Copyright © 2021 EDIZIONI MINERVA MEDICA

language: English, Italian

A step forward in the defense against infections: from gut microbiome to postbiotics

Attilio PARISI ^{1, 2} ✉, Eliana TRANCHITA ^{1, 2}, Elisa GRAZIOLI ¹, Claudia CERULLI ^{1, 2}, Antonio GIANFELICI ², Gianfranco BELTRAMI ^{2, 3}

¹ Foro Italico University of Rome, Rome, Italy; ² Federazione Italiana Medicina dello Sport (FMSI), Roma Tre University, Rome, Italy; ³ University of Parma, Parma, Italy

The immune system is extraordinarily complex and efficient, capable of distinguishing pathogenic microorganisms from those that reside normally in our intestines, better known as gut microbiota. Unlike pathogenic microbes, the microbiota microorganisms are not attacked by our immune system due to the complex, dynamic interaction between these special microorganisms and the human organism itself. It is now recognized that the human immune system is closely dependent on the instructions it continuously receives from its microbiota, which plays a key role in the development, training and functioning of our defenses. Furthermore, it has also been repeatedly reported that regular physical activity combined with a balanced diet rich in fruit and vegetables, dairy products, nuts and fish can keep our immune system functioning properly. In addition, the aging process is somehow linked to a reduction in the ability to have an adequate immune response when needed. Many studies have shown that a disruption in the balance of the gut microbiota (called dysbiosis) can lead to major alterations in the immune system, thus promoting autoimmune diseases, allergies and diminished pathogen defenses. This is why it is important to maintain a healthy microbiota through three possible strategies: use of prebiotics, probiotics and postbiotics. Postbiotics consist of substances that act indirectly on the tissues of the host organism and/or on other bacterial strains, thus helping to convey the positive effects of the probiotics. It is important to emphasize that postbiotics do not contain live microorganisms and therefore have beneficial effects similar to those of probiotics without the risk of adverse reactions as may occur when taking live microorganisms. Among the most widely used and investigated substances in the literature is a natural yeast, Saccharomyces cerevisiae, which goes through a process of fermentation and drying. In several in-vitro studies, this dried fermentate has been shown to activate natural killer cells and provide immune support against colds, flu and allergies. This can be partly explained by the documented rapid effects on immune status, which generally occur within 1-2 hours after consumption. Human studies show that these substances may play a part in reducing the severity of viral infections of the respiratory tract and shortening the duration of the infection. Strengthening the microbiota, therefore, results in improved immune system capabilities. Taking postbiotics, therefore, could help improve the body’s response to viral respiratory tract infections and probably also play a role in defending against SARS-CoV-2. This review shows that Saccharomyces cerevisiae is not only effective and simple, but also virtually free of side-effects, which is why it is recommended both for people with impaired immunity and for the healthy, as it helps to strengthen the entire immune system and maintain perfect health.

KEY WORDS: Gastrointestinal microbiome; Infections; Review