COVID-19 pandemic has plagued the entire world since early 2020 and has been ongoing for more than 2 years now. As of 2022 July, over 500 million cases and 6 million deaths due to COVID-19 has been reported [1]. With the evolution of new variants and sub-variants of COVID-19, this virus is here to stay with us. How can we reduce the severity of COVID-19 infection and the risks of developing long COVID [2]?

Recent studies have shown that severity of infection and symptoms of long COVID are associated with certain compositions of our gut microbiota. How are they related, and what can you do to lower your risks? Read on to find out more.

Understanding the gut microbiota

The gut microbiota is the unique collection of the microorganisms residing in our gut, mainly the large intestines. It includes bacterial, viral, and fungal species. The health of our digestive system is largely affected by the health of our gut microbiota, which in turn have beneficial effects on other body systems such as blood sugar [3], blood pressure [4], blood cholesterol [5], immune health [6], and many more.

This innate set of gut microbiota is thought to be the most optimum for oneself. The composition and amount of gut microbiota are affected by several factors, ranging from environmental, lifestyle, dietary habits, and antibiotics consumption [7]. The composition of good gut bacteria largely falls as we age, along with modern-day diets lacking in prebiotics (i.e., food for the good gut bacteria) and increased consumption of antibiotics.

The gut microbiota feeds on prebiotics to form metabolites such as short-chain fatty acids (SCFAs) and butyrate which confers health benefits to us. These benefits include maintaining healthy levels of blood sugar, blood pressure, blood cholesterol, and supporting immune health.

Dysbiosis refers to a change of the composition of gut microbiota due to factors like diet, toxins, drugs, and pathogens [8]. This phenomenon has been described in multiple diseases, such as obesity, diabetes, and inflammatory bowel disease (IBD). How are the composition and amount of gut microbiota going to affect the risks of contracting severe COVID-19 infection and long COVID?

Gut microbiota and its effects on severity of COVID-19 infection

It has been shown that severity of COVID-19 infection is highly associated with immune responses and inflammatory markers [9]. One study published in the medical journal Gastroenterologyin 2020 first found that there were altered gut microbiota compositions in 15 COVID-19 patients as compared to controls [10]. These patients had increased number of bad gut bacteria and reduced number of good gut bacteria [10].

In another study conducted and published in Gut(official journal for the British Society of Gastroenterology), 100 COVID-19 patients were recruited and analyzed for their gut microbiota composition in relation to their disease severity as well as levels of inflammatory markers [11]. The gut microbiota composition was hypothesized by the authors to contribute to COVID-19 severity. It was found that the number of beneficial bacterial species such as Bifidobacterium bifidum (a common probiotic species) was negatively associated with severity of disease. Increased inflammation markers were also found to be linked with altered gut microbiota composition that reflects more severe disease. This suggests that our gut microbiota could possibly play a role in modulating immune responses and COVID-19 disease severity.

Gut microbiota and its effects on Long COVID

Long COVID, also known as post-COVID conditions, can last for weeks, months and even up to years [2]. This can include a wide range of problems [2]:

• General fatigue
• Difficulty breathing
• Cough
• Chest pain
• Diarrhea

Research has also shown that composition and amount of gut microbiota affect your chances of developing long COVID. In a paper published in Gutin 2022, patients without post-acute COVID-19 syndrome (PACS) were shown to have recovered gut microbiota profile at 6 months, which is comparable to that of non-COVID-19 controls [12]. Butyrate-producing bacteria such as Bifidobacterium pseudocatenulatumwere also found to be inversely related with PACS at 6 months [12].

What can you do in this COVID-19 pandemic?

As the world move into this ‘new normal’ of living together with the COVID-19 virus, it may not be enough to simply rely on mask wearing and safe distancing. It is worthwhile to build up our gut health which is heavily involved in many other areas and systems of our body including immune health.

One way to improve the composition and health of our gut microbiota is by consuming prebiotics. A prebiotic is defined by the International Scientific Association for Probiotics and Prebiotics (ISAPP) as ‘a substrate that is selectively utilized by host microorganisms conferring a health benefit’ [13]. Prebiotics encourage the healthy balance of your unique set of resident gut microbiota, creating an environment where the beneficial bacteria (such as Lactobacillus and Bifidobacterium) flourish and crowd out unwanted and harmful bacteria. Taking prebiotics can also help to promote survival of your probiotic supplements and allow them to proliferate in your large intestines. Sources of prebiotics include food sources like wholegrains, onions, and garlic and supplements.

Conclusion

The composition and amount of gut microbiota have been shown to be associated with long COVID and disease severity in various studies. Research has demonstrated that dysbiosis is associated with increased inflammatory markers and more severe disease. Taking prebiotics can help improve the composition and health of your gut microbiota, which can potentially lower your risk of long COVID and disease severity.

Related Articles

Prebiotic: Gut Microbiota, Gut Health, and Beyond

Gut-Brain-Immune Axis: An Introduction

What is the Gut Microbiota?

References

1. World Health Organization (WHO). WHO Coronavirus (COVID-19) Dashboard.
2. Centers for Disease Control and Prevention (CDC). Long COVID or Post-COVID Conditions. 2022 Jul
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