Nikhil Prasad Fact checked by:Thailand Medical News Team Apr 23, 2025 1 month, 21 hours, 57 minutes ago
Medical News: A major new review from an international team of researchers has spotlighted a surprising culprit behind COVID-19 complications and long COVID syndromes – an invisible army of trillions living in our guts. The study, conducted by scientists from Uppsala University in Sweden, Cihan University-Erbil, Salahaddin University-Erbil, Hawler Medical University, PAR Private Hospital and Erbil Polytechnic University in Iraq, and, outlines how SARS-CoV-2, the virus behind COVID-19, disrupts the gut microbiome, leading to immune dysfunction, systemic inflammation, and even neurological and respiratory complications.
Gut Microbiome Imbalance Drives COVID-19 Severity and Complicates Recovery
While SARS-CoV-2 has been largely considered a respiratory virus, mounting evidence now confirms its ability to infect the gastrointestinal tract. This
Medical News report sheds light on how the virus attacks intestinal cells, alters gut flora, and weakens the gut barrier, causing a domino effect throughout the body. Researchers found that the virus binds to the ACE2 receptors on intestinal cells, disrupts the protective gut barrier, and triggers inflammation. As a result, toxins and pathogens that would normally be confined to the gut leak into the bloodstream, overwhelming the immune system and contributing to multiple organ damage.
Gut Imbalance Linked to Immune Chaos and Severe Disease
The research team found that COVID-19 patients suffer from a clear state of dysbiosis—a microbial imbalance in the gut. Beneficial bacteria such as Faecalibacterium prausnitzii and Bifidobacterium spp. are drastically reduced, while harmful species like Escherichia coli and Enterococcus take over. This shift in the microbial population causes inflammation, damages the intestinal lining, and drives up immune overreaction, which is a hallmark of severe COVID-19 cases.
The study also reveals that the gut microbiome doesn’t just influence digestion—it plays a crucial role in regulating the immune system, protecting the lungs, and even maintaining brain health. When this microbiome is disturbed, as it is during COVID-19 infection, the damage spreads beyond the intestines.
The Gut Lung Axis and the Worsening of Respiratory Disease
A key highlight of the review is the concept of the gut-lung axis, a two-way communication highway between gut microbes and the respiratory tract. When SARS-CoV-2 damages gut health, this axis becomes disrupted. Bacterial toxins and inflammatory molecules released from the gut travel to the lungs via the bloodstream, worsening lung inflammation and increasing susceptibility to severe respiratory failure.
Studies show that patients with severe COVID-19 often have a disrupted gut microbiota and higher levels of endotoxins in their blood. The researchers highlight that this could be one reason some patients deteriorate so rapidly even after their lung infection seems under control.
Microbiome May Be the Missing Piece in Long COVID Puzzle
The
gut microbiome's role does not end with the acute phase of the illness. Many patients report lingering symptoms for months after clearing the virus, a condition now recognized as long COVID. This new review suggests that a disrupted gut microbiome could be a major contributor. Pro-inflammatory bacteria remain dominant in many long COVID patients, while beneficial, anti-inflammatory species are depleted. This continued imbalance may drive chronic fatigue, brain fog, gastrointestinal distress, and mood disturbances.
Interestingly, the review links long COVID symptoms to microbial signatures also found in other chronic conditions such as chronic fatigue syndrome and inflammatory bowel diseases. It even identifies certain oral and gut bacteria that might travel to the lungs or bloodstream, sparking inflammation far beyond their place of origin.
Hope Through Microbiome-Based Treatments
The researchers advocate for exploring microbiome-targeted therapies in both acute COVID-19 and long COVID. Probiotics, prebiotics, and synbiotics (a mix of both) may help restore microbial balance. In addition, fecal microbiota transplants (FMT) are being investigated as a way to repopulate the gut with beneficial bacteria from healthy donors.
A particularly promising study highlighted in the review showed that a synbiotic formula known as SIM01, when given to long COVID patients, significantly improved symptoms like fatigue, memory loss, and gastrointestinal distress while restoring microbiome diversity. Patients receiving the formula had reduced inflammation markers and better overall recovery.
The Gut Brain Axis and Neurological Symptoms
Another important link highlighted in the review is the gut-brain axis. COVID-19 patients with gut dysbiosis often report neurological issues such as anxiety, depression, cognitive fog, and sleep problems. Scientists suggest that inflammation and a lack of gut-derived neuroprotective compounds may underlie these symptoms.
Healthy gut bacteria produce short-chain fatty acids (SCFAs) like butyrate that help maintain brain function and protect against inflammation. When these microbes are depleted, SCFA production drops, impairing mood, cognition, and sleep. The study draws connections between gut disturbances and disorders like Alzheimer’s and Parkinson’s, which may be worsened by SARS-CoV-2-triggered dysbiosis.
Microbiome Monitoring Could Guide Diagnosis and Treatment
The authors emphasize the potential of using the gut microbiome as a diagnostic and prognostic tool. In one study, five specific gut bacterial strains were identified that could distinguish COVID-19 patients from healthy individuals. Another investigation found that the presence or absence of certain microbial species could predict which patients would suffer severe disease or develop long COVID.
This opens the door to personalized medicine approaches where doctors could tailor treatments based on a patient’s microbial profile. In the future, stool analysis might help forecast disease outcomes and guide therapeutic strategies to restore gut balance.
Conclusion
This groundbreaking review makes it clear that the gut microbiome plays a central role in shaping the course of COVID-19 and its aftermath. Disruption of gut bacteria leads to widespread immune imbalance, inflammation, and multi-organ involvement. By influencing the lungs, brain, and metabolic functions, gut dysbiosis may be the hidden engine behind both severe acute illness and the lingering symptoms of long COVID.
Addressing this microbial chaos through microbiome-restoring therapies offers a promising new frontier in COVID-19 treatment. But more clinical trials and long-term studies are needed to refine these interventions and integrate microbiome monitoring into mainstream care.
The study findings were published in the peer reviewed journal: Frontiers in Cellular and Infection Microbiology.
https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2025.1537456/full
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