The Microbiome and COVID-19
Although COVID-19 is primarily a respiratory illness, there is strong evidence suggesting that the gut is involved. Associations between gut microbiota composition and levels of inflammatory markers in patients with COVID-19 suggest that the gut microbiome affects the severity of the disease.
A study conducted by researchers at King’s College London looked at samples of gastrointestinal tracts from patients who had died after being diagnosed with COVID-19 during the first wave of the pandemic. The researchers found that the system that normally regulates the composition of microbial communities in the gut, known as Peyer’s Patches, were disrupted in severe COVID-19. This was irrespective of whether there was evidence of virus present in the gut or not.
The Gut, Immunity and Long Covid
Patients with long Covid tend to have impaired immunity and reduced microbial diversity alongside an increase in opportunistic bacteria, viruses and fungi such as Candida. These may affect the gut microbiome post COVID-19 and lead to persistent symptoms (1,2,3). Improving gut microbiota profile through personalised nutrition and supplementation could help to minimise the impact of the disease in old people and immune-compromised patients in particular (4,5).
Dysbiosis leads to a leaky gut. This increased intestinal permeability means bacterial products and toxins enter the circulatory system and further exacerbate the systemic inflammatory response (6). Poor prognosis in COVID-19 infection is seen in patients with underlying co-morbidities who have increased gut permeability and reduced gut microbiome diversity.
Diet, Probiotics and Prebiotics
Probiotics improve the gut microbiota and the immune system by regulating the innate immune system and production of anti-inflammatory cytokines. It’s suggested that probiotics could decrease susceptibility to viral respiratory infections, such as COVID-19, and simultaneously enhance vaccine efficiency.
Probiotics vary in their effectiveness depending on the conditions. Their efficacy can be improved through combining with supplements such as prebiotics, postbiotics, nutraceuticals, berberine, curcumin, lactoferrin and vitamins and minerals such as vitamins C and D and zinc (7).
These combined with a more diversified diet alongside probiotics and prebiotics could help to strengthen the intestinal barrier and lower inflammation and thus may mitigate the effects of respiratory infections such as Covid (8,9).
The gut microbiome plays a significant role in immune regulation, inflammation and the ability to challenge pathogens meaning it may be pivotal in influencing the immune response to COVID-19 and other infections. The gut microbial ecological network is significantly weakened in patients with severe COVID-19. Supporting the gut through diet and supplements is recommended to prevent further infections and to aid recovery from past infections.
For more information on how the microbiome can be impacted by what we eat read the blog post Food for the Microbiome. The blog post Microbiome, Stress and Anxiety highlights the interaction between the gut microbiome and the brain.
1. Genomics Proteomics Bioinformatics. 2021 Sep 21;S1672-0229(21)00206-0. Gut Microbiome Alterations in COVID-19. Zuo T et al.
2. 2021 Apr;70(4):698-706. Gut microbiota composition reflects disease severity and dysfunctional immune responses in patients with COVID-19. Yeoh YK et al
3. Trevelin SC et al. Disrupted Peyer’s Patch Microanatomy in COVID-19 Including Germinal Centre Atrophy Independent of Local Virus. Frontiers in Immunology, 2022; 13
4. Virus Res. 2020 Aug;285:198018. Gut microbiota and Covid-19- possible link and implications. Dhar D, Mohanty A.
5. Therap Adv Gastroenterol. 2020 Nov 24;13:1756284820974914. The gut microbiome: an under-recognised contributor to the COVID-19 pandemic? Segal JP et al.
6. Front Immunol. 2021 Oct 14;12:765965. Role of Gut Microbiome in COVID-19: An Insight Into Pathogenesis and Therapeutic Potential. Hussain I et al.
7. Recent Pat Biotechnol. 2021 Oct 4;15(2):112-136. Probiotics/Prebiotics in Viral Respiratory Infections: Implication for Emerging Pathogens. Heidari Z et al.
8. Trends Food Sci Technol. 2021 Feb;108:187-196. Review article: Probiotics, prebiotics and dietary approaches during COVID-19 pandemic. Hu J et al.
9. Br J Nutr. 2021 Jul 28;126(2):219-227. Mechanisms linking the human gut microbiome to prophylactic and treatment strategies for COVID-19. Walton GE et al.