The Gut Microbiome & Long COVID: Interview with Dr. Leo Galland

Hosted by the Microbiome Foundation, this discussion with Dr. Leo Galland explores the critical connection between the gut microbiome and Long COVID, focusing on how SARS-CoV-2 alters gut health and how microbiome-targeted interventions may help recovery.

The Gut Microbiome: A Key Player in Health & Immunity

Dr. Galland describes the gut microbiome as an integrated, dynamic ecosystem, influencing immune function, metabolism, gene expression, and inflammation.

What is the Gut Microbiome?

✅ Covers every surface of the body, especially the gastrointestinal (GI) tract.
✅ Produces molecules that regulate immunity, inflammation, and gene expression.
✅ More microbial cells & DNA exist in the gut than human cells & DNA.
✅ Functions like a "bioreactor", shaping metabolism and immune responses.

Key Microbiome Factors That Affect Health:

✔️ Dysbiosis → An imbalance in gut bacteria that disrupts immune and metabolic functions.
✔️ Leaky Gut (Intestinal Hyperpermeability) → A weakened gut lining that allows toxins & microbes to enter the bloodstream, triggering inflammation.
✔️ Stress & Microbiome Interactions → Stress hormones like adrenaline promote harmful bacterial growth, contributing to inflammation and gut permeability.

How COVID-19 Impacts the Gut Microbiome

1. SARS-CoV-2 Directly Infects the Gut Lining

• ACE2 receptors (the virus's entry point) are highly expressed in the small & large intestines.

• Virus attachment damages ACE2, impairing amino acid absorption, serotonin production, and immune defense peptides (defensins).

• COVID-19 viral RNA persists in the gut for up to 7 months in some patients, even after recovery.

2. COVID-19 Alters Gut Bacteria Composition

🔹 Decreases beneficial bacteria (e.g., Faecalibacterium prausnitzii, Bifidobacteria).
🔹 Increases inflammatory bacteria (e.g., Ruminococcus gnavus, Candida albicans, Aspergillus flavus).
🔹 Leads to a persistent state of inflammation & microbiome dysfunction seen in Long COVID.

3. The Gut Microbiome at Infection Onset Predicts Long COVID Risk

🔍 A study found that patients who later developed Long COVID had:
❌ Lower levels of beneficial bacteria (Faecalibacterium prausnitzii and Bifidobacteria).
❌ Increased inflammatory microbes (Ruminococcus gnavus, Bacteroides species).
❌ Higher gut permeability ("leaky gut"), allowing microbial toxins into the bloodstream.

The Gut Microbiome & Long COVID Symptoms

1. Persistent Inflammation & Autoimmune-like Reactions

• Loss of Faecalibacterium prausnitzii reduces butyrate production, leading to:
  🔴 Increased inflammation
  🔴 Weakened gut barrier function
  🔴 Higher risk of autoimmune activation

2. Neurological Symptoms ("Brain Fog")

• COVID-related dysbiosis leads to reduced production of butyrate, which normally:
  🧠 Supports brain function
  🧠 Promotes neuroplasticity via BDNF (Brain-Derived Neurotrophic Factor)
  🧠 Reduces neuroinflammation

• Overgrowth of toxic microbes like Ruminococcus gnavus produces neurotoxic compounds linked to cognitive dysfunction.

3. Increased Gut Permeability ("Leaky Gut")

• COVID-19 weakens the gut lining, allowing microbial toxins & fungal components (β-glucans) to enter the bloodstream, which:
  ⚠️ Triggers systemic inflammation
  ⚠️ Worsens Long COVID symptoms (fatigue, neuropathy, joint pain, nausea, insomnia)

4. Increased Susceptibility to Other Infections

• Post-COVID microbiome disruption reduces immune defense peptides (defensins), making people more prone to:
  ❌ Bacterial infections
  ❌ Fungal overgrowth (Candida, Aspergillus)

Strategies to Restore Gut Health & Manage Long COVID

1. Diet: The Foundation for Microbiome Recovery

✅ Pesco-Vegetarian / Mediterranean Diet → Increases Faecalibacterium prausnitzii and butyrate production.
✅ High-Fiber & Polyphenol-Rich Foods → Found in berries, green tea, olive oil, dark chocolate.
✅ Prebiotic Foods → Support beneficial bacteria (onions, garlic, leeks, bananas).
❌ Avoid Processed Sugars & High-Fructose Corn Syrup → Prevents inflammatory bacterial overgrowth.

2. Key Probiotics & Supplements

SupplementBenefitsBifidobacterium (BB536, Wangam 51A)Supports immune balance & gut barrier integrityFaecalibacterium prausnitzii-supporting prebioticsIncrease butyrate production, improve gut functionSodium Butyrate (Postbiotic)Directly restores gut barrier integrity & reduces inflammationOmega-3 Fatty AcidsReduce gut inflammation & improve microbiome diversityCurcumin & QuercetinCombat gut inflammation & enhance gut lining repair

3. Targeted Treatments for Gut Inflammation

• Probiotics (e.g., Bacillus subtilis, found in Tundrex) help restore gut microbiome balance.

• Quercetin, Curcumin, Magnolia Bark, and Mastic Gum help reduce gut inflammation & repair intestinal lining.

• Bovine Immunoglobulins (Serum IgG) can neutralize gut toxins and support immune balance.

4. Anti-Viral & Gut-Specific Therapies

• Paxlovid (Antiviral) reduces Long COVID risk by 40%.

• Natural antivirals (e.g., green tea polyphenols, EGCG, and resveratrol) may help reduce viral persistence in the gut.

Final Takeaways: The Microbiome’s Role in Long COVID Recovery

🔹 COVID-19 alters the gut microbiome, leading to persistent inflammation, gut permeability, and immune dysfunction.
🔹 Loss of beneficial gut bacteria (especially Faecalibacterium prausnitzii) is linked to Long COVID symptoms.
🔹 Restoring gut health through diet, probiotics, and anti-inflammatory supplements may help alleviate Long COVID symptoms.
🔹 Polyphenol-rich, fiber-heavy diets & microbiome-supporting supplements are promising interventions.

By targeting the gut microbiome, we may improve Long COVID outcomes and promote faster recovery.