Recent studies state that probiotics may help flatten the curve by making people more resilient to viral infections. Certain probiotic strains are also hypothesized to reduce the risk of severe COVID-19 symptoms and complications, possibly by balancing the immune response. Prebiotics might play in by “feeding” probiotics and enhancing their beneficial effects.
Lactobacillus reuteri (L. reuteri) is a well-studied probiotic species that can secrete a cocktail of antimicrobial compounds. These compounds are meant to prevent viruses from spreading in the whole body—not just in the gut. For example, in one study, L. reuteri applied into the nose protected mice from a deadly respiratory virus that causes pneumonia.
Additionally, probiotics may reduce respiratory damage from COVID-19 by activating gut-lung communication. Studies have yet to investigate L. reuteri, but the results on similar probiotics (L. rhamnosus and B. Subtilis and E. faecalis) are promising. In two studies, COVID-19 patients on ventilators who were given probiotics were less likely to get pneumonia. However, more research is needed.