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Gut Issues and COVID-19: How are they related?


Written by: CDHF

Updated: November 29th, 2022

Since the beginning of the pandemic, there have been a few symptoms that have become synonymous with having COVID-19, including fever, cough, and fatigue. Additionally, a study retroactively revealed that another symptom is quite common – diarrhea. This news shines light on just how linked gut issues and COVID-19 may be. (1)

What gut issues could I have with COVID-19?

Symptoms of COVID-19 can differ greatly from person to person, in addition to varying between age groups. Variants (and the potential variants) of COVID-19 also play an important role, as the Omicron variant can present itself differently than the original virus. It is important to note that symptoms may take a full 14 days to appear after exposure. The Government of Canada indicates that common reported symptoms may be broadly categorized as “more frequent”, “less frequent” and “rare”. Gastrointestinal symptoms such as nausea, vomiting, and diarrhea fall into the more frequent category. (2)

As doctors learn more about COVID-19, a study has shown that digestive symptoms, in particular diarrhea, could be a symptom for people who have a mild form of COVID-19 (without difficulty breathing or low blood oxygen levels).  In a study published in the American Journal of Gastroenterology, patients in this unique sub-group showed that diarrhea can be the initial presentation of COVID-19, and patients may only later or never present respiratory symptoms or a fever. (1, 3)

In more detail, this study showed that 23% of patients were admitted with digestive symptoms, 43% with respiratory symptoms only, and 33% with both respiratory and gastrointestinal symptoms.

Among the patients with gastro symptoms, 67% of them had diarrhea, and 20% experienced diarrhea as the first symptom of their illness. Diarrhea lasted an average of 5 days, and about one-third of patients with gastro symptoms never experienced a fever. The study also found that those with gastrointestinal symptoms were much more likely to have the COVID-19 detected in their stool samples, with about 73% of patients testing positively compared with 14% of those with respiratory symptoms only. (3)

More recently, a study showed that nearly one in five people with COVID-19 may only have gastrointestinal symptoms. Gastrointestinal symptoms associated with COVID-19 vary widely but for this study they included loss of appetite, nausea, vomiting, diarrhea and generalized abdominal pain. Researchers reported that 18% of patients presented with such symptoms, while 16 per cent of COVID-19 cases may only present with gastrointestinal symptoms. (4)

Diagnosis should always be confirmed by laboratory testing, and you should seek medical consultation if experiencing new or worsening symptoms.

Can my gut health change the severity of my COVID-19 immune response?

Although COVID-19 is primarily a respiratory illness, there is mounting evidence suggesting that the GI tract is involved in this disease. The variety and volume of bacteria in the gut, known collectively as the gut microbiota, may influence both the severity of COVID-19 as well as the magnitude of the immune system response to the infection. Imbalances in the make-up of the gut microbiota may also be implicated in persisting inflammatory symptoms, otherwise referred to as ‘long COVID’. (5, 6, 7)

What is the gut microbiota?

Scientists have discovered that our entire bodies, both inside and out have been invaded! By microbes! These tiny visitors are collectively referred to as your microbiome. The majority of your microbiome sets up house in your digestive tract – specifically your colon. The gut microbiota is the population of bacteria, viruses, and fungi living all along the length of the intestines, and they work hard every day to keep you healthy and prevent disease. (7)

Immune cells in the gut interact with the gut microbiota and are directly influenced by an individual’s diet and lifestyle. Those gut microbes are healthiest and support strong immunity when their hosts (that’s us) consume a healthy, balanced and diverse diet. (8, 9)

Will I have gut issues after COVID-19?

Although severe COVID-19 illness typically lasts two to six weeks, some patients have reported debilitating symptoms persisting or recurring for weeks or months after COVID has ended. It was found that 83% of the individuals reported persistence or presence of one or more short-term symptoms and 56% reported long-term symptoms. The most common symptoms in both periods include fatigue, general pain or discomfort, sleep disturbances, shortness of breath, anxiety or depression, and long-term gastrointestinal effects.

Loss of appetite was the most common gastrointestinal long-term consequence. Others were nausea, acid reflux, diarrhea, abdominal distension (protruding belly), vomiting, abdominal pain, and bloody stools. These symptoms are common even 3 months after a patient has been considered free of COVID-19. (10)

Should I get the COVID-19 vaccine if I have gut issues?

The Canadian Association of Gastroenterology released guidelines for COVID-19 vaccines regarding people living with inflammatory bowel disease (IBD) specifically. They strongly recommended that people with IBD who are not receiving immunosuppressive therapies get the vaccine. If an individual is receiving immunosuppression therapy, they should consult their physician before receiving a vaccine.

It is important to note that an IBD diagnosis does not make an individual immunosuppressed, instead, some IBD treatments might cause immunosuppression. (11)


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