Probiotics & immunity: A review on how to select the right strains for a safe and effective supplement


Formerly area sales manager and Product Development at Probiotical, Italy


In the context of the coronavirus pandemic, more and more attention is brought to the impact of gut microbiota dysbiosis on the severity of the disease.

Probiotics can also play a role, as strains have demonstrated to reduce the prevalence, severity and duration of other viral infections. While no probiotics to date have demonstrated benefits against COVID-19 infection, some probiotic bacteria present very interesting traits for the balanced stimulation of the immune system and protection from viral and bacterial infections. 

This article’s objective is to summarize the main characteristics such probiotics should present, and describe the clinical efficacy obtained with carefully selected strains. The discussed synbiotic formulation was found to significantly reduce the number of episodes, severity and duration of acute respiratory infections and colds.


The global Covid-19 crisis led to increased attention towards preventative health leading to a surge in demand for immune defense supplements, including in the probiotics category.

Indeed, we now know that over 70% of our immune cells are situated in the gut, and through the immune system’s co-evolution with our gut microbiota, a significant part of the education and maturation of our immune cells is carried out by their interaction with our microbes. Such contacts hone the immune system’s capacity to recognize friend from foe (1-5) and even improve the response to vaccination (6, 7).

The modern way of life is disturbing the symbiosis, and more than ever we need to re-establish microbes as key partners of our health to ensure that our immune system, our first line of defense is functioning at its best. One of the ways to support this balance is through probiotics.

At the beginning of 2020, the year the Chinese authorities made an official recommendation for patients with Covid-19 to take probiotics in order to maintain the gut microbiota balance and to prevent secondary bacterial infections (8, 9). Actually, the m ...