Is there a link between Covid-19 and gut health?
Research in recent years has certainly pointed heavily towards there being a link between immunity and gut health. It follows that a poor gut microbiome may increase susceptibility to a virus attack. Once a virus is resident does the quality of the gut microbiome protect you from the severity of the attack?
Covid -19 has been seen to affect the gastrointestinal tract in the form of diarrhoea, nausea and vomiting. Researchers have shown there seems to be a clear connection between altered gut microbiome and severe COVID-19. They have also indicated a dysbiotic gut microbiome composition in patients with Covid -19 persists long after the virus is gone.
Role of gut microbiota in immunity
Studies have suggest that SARS-CoV-2 infected patients first develop a fever, then respiratory symptoms, followed by GI tract symptoms. The virus spike protein interacts with cells in the epithelial lining of the organs especially the lungs, but also the GI tract via a molecular pathway of angiotensin-converting enzyme (ACE2) leading to a series of chemical reactions resulting in intestinal inflammation. This has been seen in the post mortem pathology of Covid -19 patients.
A growing body of studies have looked at the gut microbiome of the healthy vs the COVID-19 patient. It seems that those with underlying conditions including hypertension, diabetes and obesity as well as the elderly have a microbial dysbiosis and an inflamed gut lining resulting in a disrupted gut barrier integrity. This allows the virus to gain access to the enterocytes leading to the extensive organ damage seen in severe COVID-19.
Conversely a healthy GI tract with a high butyrate content and a subsequent increase in T cells results in the virus being contained in the GI tract and excreted in the faeces.
In a recent study it was shown that this gut dysbiosis extended up to 30 days post Covid and could be a contributor to the pathogenesis of ‘long-Covid’ and its on going health complications.
Which specific gut bacteria are we talking about?
In Covid -19 patients across the research there was a reduction in certain bacteria known to be beneficial. These are the Ruminococcaceae or Lachnospiraceae, a single species F. prausnitzii, and the class Clostridia .These are some of the major butyric acid-producing bacteria in the gut.
Butyric acid is a short-chain fatty acid (SCFA), which, along with propionic and acetic acids, is a fermentation product of the microbe and dietary fibre that plays a pivotal role in gut health. It aims to maintain gut barrier integrity by serving as an important energy source for colonocytes, allowing these cells to activate an anti-inflammatory and anti – allergic response.
Depletion of certain butyric acid producers in the gut microbiota has been identified in a few chronic diseases, including allergies, inflammatory diseases, colorectal cancer, and Crohn’s disease.
Possible interventions to improve gut health and protect the gut in Covid -19 have been considered:
- Faecal Microbiota transplant – an option that has been suggested for severe COVID -19 but not investigated.
- Next generation probiotics with a focus on butyrate producers are also considered novel microbial therapeutics and still under scrutiny.
- Increased dietary fibre intake – the simplest way to improve gut health , fibre being directly utilized by the butyrate producers amongst other beneficial bacteria.
Eating to boost your gut immunity
We know it is possible to increase the diversity of your microbiome by eating lots of plant-based foods.
The Mediterranean diet has been linked to improved gut diversity and reduced inflammation which may indeed protect from pathogens like the Covid-19 virus
The Mediterranean diet contains a diverse mix of fruit and vegetables , wholegrains, legumes, pulses, nuts and seeds. These contribute important vitamins and minerals for supporting immunity but also act as a fuel source for the gut microbiome.
Probiotic rich foods may also support the microbiome like yoghurt, cheeses and fermented foods.
This is just the start
We are starting to understand more about our complex microbiological world. The impact of the status of our gut health goes far beyond the Covid-19 pandemic . In the future we will continue to deal with an ever increasing incidence of chronic diseases. The links between these and a damaged microbiome are becoming more and more prevalent. It seems that an improved diverse fibre rich diet is going to become more and more important in disease prevention.