Increasing evidence has shown that our gut microbiome plays an important role in our immune system.
When viruses are exposed to mucosal surfaces (e.g., vaginal, respiratory, or GI) they have three broad lines of defence to overcome: the mucus layer, innate immune defences and adaptive immune defences. Recent evidence has suggested that both commensal and probiotic bacteria influence each of these lines of defence.
The antiviral mechanisms responsible are both direct and indirect and include:
1) Enhanced mucosal barrier function 2) Secretion of antiviral antimicrobial compounds 3) Inhibition of viral attachment to host cells 4) Modulation of immune system
Image adapted from: Harper et al. Viral Infections, the Microbiome, and Probiotics. Front. Cell. Infect. Microbiol 2021 10:596166
When the communication between our gut microbiome and immune system becomes disrupted, it can have a negative impact on our response to viral infections. This can be caused when our gut microbiome becomes unbalanced, otherwise known as dysbiosis. This is when there is a decrease in organisms considered to be beneficial (e.g., Bifidobacterium, Akkermansia or Faecalibacterium species) or a reduction in diversity. The significance of this was demonstrated in a paper published in 2021 by YK Yeoh et al., which showed that differences in gut microbiome composition, including a decrease in Faecalibacterium, was correlated with Covid-19 diagnosis and severity (link to article).
Additionally, research has shown that a dysbiosis gut microbiome can affect the gut-lung axis, the two-way communication between our gut and lung microbiome (link to article). A healthy gut microbiome offers protection against respiratory infection by maintaining a normal immune response. Dysbiosis of the gut microbiome can affect the signalling between the gut and lung which as a result, can impact antiviral immune response in the lungs. Research has shown that taking beneficial bacteria supplements can help support and recovery effect immune function in the gut microbiome and also the lung.
Whilst this research is still relatively new, it demonstrates the important role our gut microbiome plays in the progression and severity of viral infections and therefore, how vital it is to look after our gut microbiome.
Harper, A., Vijayakumar, V., Ouwehand, A., ter Haar, J., Obis, D., Espadaler, J., Binda, S., Desiraju, S. and Day, R., 2021. Viral Infections, the Microbiome, and Probiotics. Frontiers in Cellular and Infection Microbiology, 10.