PROBIOTICS

What are probiotics?

Probiotics are helpful microorganisms that can benefit the body when eaten or applied. They include bacteria, such as those from the group Lactobacillus, or other microorganisms, such as yeasts, including Saccharomyces boulardii [^[1]].

What do probiotics do in the body?

Probiotics are a range of different microorganisms, so each probiotic may work differently. They can affect the immune system, help one’s body have a normal level of gut microorganisms, or even produce compounds beneficial for the body [^[1]]. Probiotics can have immunomodulatory, antioxidant, and antiviral effects. They can improve cognitive function, reduce physical and mental fatigue, regulate brain health, improve sleep quality, and boost mood [^[2]].

How can probiotics help alleviate certain Long COVID symptoms and pathophysiology? 

The acute COVID-19 phase is associated with gastrointestinal systems such as diarrhea, nausea, vomiting, and loss of appetite. Furthermore, SARS-CoV-2 RNA can be found in stool samples even after the virus clears the respiratory tract [^[3]]. Changes in gut microorganisms are linked to COVID-19 severity, possibly resulting from a post-COVID-19 “leaky gut” [^[3]].

The gastrointestinal system is implicated in acute COVID-19 infection and Long COVID [^[4]]. The severity of gut and lung microbiomes in COVID-19 and the effect of probiotics on these microbiomes remain under investigation by researchers. A systematic review showed that COVID-19 altered the microbiome, making opportunistic pathogens more prevalent. Furthermore, stress, hospitalization, and the actions of the SARS-CoV-2 virus directly on receptors in the gastrointestinal system are linked to gut microbiome imbalance. The altered microbiome may also change the lungs’ response to respiratory infections by modulating immune responses, and these changes may persist way after acute COVID-19 infection. Therefore, improving or supplementing the gut-lung microbiome axis is of interest in Long COVID. Probiotics such as Bifidobacteria and Lactobacilli may modulate immune function in the gut-lung axis [^[5]].