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The Challenge
What can you do to support immunity as winter comes and seasonal viruses emerge once again?
Well, there are many potential answers to this!
Our immune status is constantly adjusting and is influenced by a matrix of factors:
- Our age
- Our health status
- Our stress levels
- Our nutrition status
- Our exercise levels
- Our gut microbiota profile
- Our vitamin D status
- Our sleep quality
This is not an exhaustive list, but hopefully, a helpful one.
Now, we understand it might be hard to make big changes right now. We are also mindful that winter is coming, and there will be a normal rise in seasonal viruses.
With this in mind, what simple areas can we focus on to support the breadth and depth of our immunity this winter?
One great area to focus on is gut health because our immune system interfaces closely with the gastrointestinal tract. Indeed, it’s been estimated that about 70% of immune-sensing cells reside in the gut.
In other words, you can’t really talk about the immune system without also talking about the gut.
"It's been found that about 70% of immune-sensing cells reside in the gut. In other words, you can't really talk about the immune system without also talking about the gut."
- Justin Buckthorp, MSc
The Gut-Covid Link
The first question to ask is why probiotics might be helpful in a viral infection like Covid-19?
There are many answers to this, but fundamental to all of them is emerging research that shows gut dysbiosis is a contributing factor that predicts disease severity with Covid-19.
Back in 2020, as the pandemic first unfolded, research out of Hong Kong found that a loss of beneficial microbes and an increase in opportunistic gut microflora was associated with worse outcomes in hospitals. Another study found that a fungal infection in the gut called Candida albicans also appeared to have affected Covid-19 outcomes.
On top of that, it was found very early in the pandemic that viral RNA from SARS-CoV-2 could be found in stool. This indicates the viral replication was also happening in the gut, which may explain some of the symptoms in those that contract Covid-19, such as diarrhoea.
The microbiome in the gut also communicates with the microbiome in the lung. This Gut-Lung Axis is important in Covid-19 outcomes. Perhaps this is why a recent meta-analysis of randomised controlled trials (the top of evidence-based medicine hierarchy) found that probiotics could shorten hospital stays for those with pneumonia compared to controls.
Evidence for Probiotics in Covid-19
There are insufficient published randomised controlled trials at the moment for us to really understand the potential efficacy of probiotics in preventing or ameliorating the effects of SARS-CoV-2.
Currently, 19 clinical studies are underway investigating the potential use of probiotics in Covid-19, and more will get underway over time. We need to understand not just efficacy but dose (how much to take), timing (when to take), and specificity (how different populations might need differing amounts or types of prebiotic and probiotic).
This does not mean we shouldn’t use probiotics as part of our toolkit in supporting wider immunity. There is clear evidence that probiotics can help with upper respiratory viral infections, of which Covid-19 is one.
For example, a recent systematic review of 31 studies found probiotics could reduce symptoms and duration of respiratory illness, support immune biomarkers, and increase anti-oxidant status.
There are also many ways that probiotics might be of value in supporting our defence networks in the body by:
- Preventing intestinal permeability
- Competing with unwelcome pathogens in the gut
- Producing anti-inflammatory short-chain fatty acids (such as butyrate)
- Modulating the immune system in the gut and lungs
For more information on this, check out a recent paper published in the World Journal of Gastroenterology. The authors of this paper concluded:
“In these trying times of the COVID-19 pandemic, the connotation of a healthy gut-healthy mind could translate into one’s ability to orchestrate a meaningful immune response that could limit SARS-CoV-2 infection and maintain systemic homeostasis and diminish side effects from virus exposure. Leveraging therapies currently being used to improve gut health could be exploited for better disease outcomes during severe disease.”
Gut health is central to our physical and mental wellbeing and can be a major force for good in supporting immune resilience in the presence of SARS-CoV-2.
