Diseases, Gut-Lung Axis

The Gut-Lung Axis and GERD

Below, I’ll provide additional details on the link between gut dysbiosis, acid reflux (GERD), and asthma, focusing on recent research (2023–2025) on the gut-lung axis and practical strategies for managing GERD in the context of dysbiosis, tailored to a client’s situation (Candida overgrowth, leaky gut, long-term PPI, corticosteroid, antibiotic, and thyroid medication use).
I’ve incorporated relevant insights from recent studies to deepen the understanding of these connections and offer actionable guidance.

Expanded Insights on the Gut-Lung Axis and Disease Connections
The gut-lung axis is a bidirectional communication pathway between the gut and lungs, mediated by microbial metabolites, immune responses, and systemic inflammation. Recent research (2023–2025) strengthens the evidence linking gut dysbiosis, GERD, and asthma, with implications for your client’s health.

  1. Gut Dysbiosis and GERD:
    • Mechanisms: Gut dysbiosis, such as your client’s Candida overgrowth, disrupts the gut microbiome, reducing beneficial bacteria (e.g., Lactobacillus, Bifidobacterium) and increasing pathogens. This imbalance can impair gut motility, increase intra-abdominal pressure, and weaken the lower esophageal sphincter (LES), promoting GERD. Long-term PPI use (like Prilosec) exacerbates dysbiosis by reducing stomach acid, allowing overgrowth of fungi like Candida or bacteria linked to small intestinal bacterial overgrowth (SIBO), which can worsen reflux symptoms.
    • Recent Research:
      • A 2023 study in Respiratory Medicine Research found that dysbiosis and leaky gut in COPD patients (relevant to asthma) were associated with increased GERD prevalence, suggesting that gut microbial imbalances contribute to esophageal inflammation and reflux.
      • A 2024 Heliyon study highlighted that gut dysbiosis alters tight junction proteins (e.g., claudin-2), increasing intestinal permeability and systemic inflammation, which may exacerbate GERD by promoting esophageal irritation.
    • Our Client’s Context: A history of antibiotics, corticosteroids, and PPIs likely worsened dysbiosis, contributing to GERD.
      Candida overgrowth may further drive inflammation, weakening the LES and perpetuating reflux.

  2. Gut Dysbiosis and Asthma:
    • Gut-Lung Axis: The gut microbiome influences lung immunity via metabolites like short-chain fatty acids (SCFAs, e.g., butyrate), which reduce airway inflammation. Dysbiosis reduces SCFA production, promoting Th2-mediated inflammation (common in asthma) and airway hyperresponsiveness.
    • Recent Research:
      • A 2024 Clinical and Translational Allergy review emphasized that early-life antibiotic exposure (relevant to your client’s history) disrupts gut microbiota, increasing asthma risk by altering immune cell maturation and Th1/Th2 balance. Probiotics may mitigate this risk by restoring gut flora.
      • A 2024 Oxford Open Immunology study noted that gut mycobiome dysbiosis (e.g., Candida overgrowth) can exacerbate asthma by triggering immune responses via fungal cell wall components (e.g., β-glucans), which activate inflammatory pathways in the lungs.
      • A 2025 Frontiers in Immunology article highlighted that gut dysbiosis in allergic asthma patients correlates with reduced SCFA levels, increasing airway inflammation.

    • Our Client’s Context: Candida overgrowth and PPI-induced dysbiosis may contribute to systemic inflammation, potentially worsening asthma (if present) via the gut-lung axis.

  3. GERD and Asthma:
    • Mechanisms: GERD can exacerbate asthma through:
      • Microaspiration: Refluxed acid or gastric contents enter the lungs, causing airway irritation and bronchoconstriction.
      • Vagal Reflex: Esophageal acid stimulates vagus nerve-mediated bronchospasm.
      • Inflammation: Reflux triggers cytokine release, increasing airway inflammation.
    • Recent Research:
      • A 2023 Medicina study found that COPD patients (with similar airway dynamics to asthma) had a 1.165-fold higher risk of erosive esophagitis (EE), a severe GERD form, due to reflux-induced airway inflammation.
      • A 2023 AGA Clinical Practice Update noted that 30–80% of asthma patients have GERD, with microaspiration and vagal reflexes as key mechanisms. It emphasized that GERD may lack classic symptoms (e.g., heartburn) in asthma patients, complicating diagnosis.
      • A 2024 Heliyon study confirmed that GERD worsens asthma via tracheal acid exposure, which increases airway resistance more significantly than esophageal acid alone.
    • Our Client’s Context: The GERD (managed with Prilosec) may contribute to respiratory symptoms if asthma is present, especially if microaspiration occurs. The lack of morning hunger suggests possible hypochlorhydria, which may exacerbate dysbiosis and GERD.

  4. Bidirectional Interactions:
    • Asthma can worsen GERD by increasing lung hyperinflation, reducing LES pressure, and promoting reflux. Medications like corticosteroids (used previously by your client) can relax the LES, further aggravating GERD.
    • Dysbiosis amplifies both conditions by driving systemic inflammation, creating a feedback loop where gut, esophageal, and airway health deteriorate together.

Practical Strategies for Managing GERD with Dysbiosis

Given our client’s Candida overgrowth, leaky gut, and PPI use, here are evidence-based strategies to manage GERD while addressing dysbiosis, complementing the existing L-glutamine gut healing protocol and anti-Candida diet plan:

  1. Optimize Gut Health to Reduce Dysbiosis:
    • Continue L-Glutamine: The 5g three-times-daily dose is well-supported for leaky gut repair and may reduce dysbiosis-driven inflammation, indirectly improving GERD. A 2020 study in Nutrients showed L-glutamine reduces acid injury in the esophagus, supporting its role in GERD management.
    • Probiotics: Introduce a high-potency, multi-strain probiotic (e.g., Lactobacillus rhamnosus, Bifidobacterium longum, or Saccharomyces boulardii) taken at night, away from meals and PPIs, to restore gut flora. Since many clients have issues processing gelatin capsules, you can open it and pour the powder in an adequate quantity of room temperature water and drink it.
      An alternative is to spread it on salads or food, or mix it in yoghurt or smoothies.
      A 2024       Clinical and Translational Allergy study found probiotics reduced asthma severity by modulating the gut-lung axis, which may also help GERD.

      • Dose: 10–50 billion CFU/day, starting low to avoid bloating.
      • S. boulardii: Particularly effective against Candida overgrowth, as it inhibits fungal adhesion.
    • Prebiotics: Include prebiotic fibers (e.g., inulin from chicory root or resistant starch from green bananas or boiled brown rice or baked potatoes consumed the second day – so the starch can become resistant). Add fiber from these starches, in small amounts to feed beneficial bacteria, Candida patients should introduce this fiber gradually, to avoid gas.
    • Anti-Candida Diet: Continue low-sugar, low-carb foods (e.g., leafy greens, eggs, avocado) to starve Candida. Add antifungal foods like garlic, oregano oil (in capsules, under medical guidance), or coconut oil (1–2 tbsp/day), which a 2023 Frontiers in Microbiology study linked to reduced fungal dysbiosis.
  2. Manage GERD Symptoms:
    • Review PPI Use: Long-term PPIs like Prilosec worsen dysbiosis and Candida overgrowth, potentially perpetuating GERD. Discuss with your doctor whether PPIs can be tapered (e.g., switch to H2 blockers like ranitidine or lifestyle interventions: sleep and moderate exercise – avoiding any processed foods, vegetable seed oils, fast foods, fried foods, pesticides, fungicides, etc – buy organic.
      Discuss with your doctor if you can try apple cider vinegar in water -1 tablespoon in an 8 oz glass of water after meals) to restore stomach acid and reduce dysbiosis.
      A 2023       AGA Clinical Practice Update suggests evaluating GERD’s extraesophageal symptoms (e.g., cough, asthma) to determine if PPIs are necessary.

    • Dietary Adjustments:
      • Small, Frequent Meals: Eat 4–5 small meals to reduce stomach pressure and LES strain. Avoid trigger foods (e.g., spicy, fatty, citrus, caffeine, alcohol). Try the raw apple cider vinegar method. 
      • Timing: Avoid eating 2–3 hours before bed to minimize nighttime reflux, as recommended by the Asthma and Allergy Foundation of America.
      • Digestive Aids: Under medical supervision, try apple cider vinegar (1 tsp in water before meals) or bitters to stimulate digestion, especially if low HCl is suspected. Avoid with active ulcers or PPI use unless cleared by a doctor.
    • Lifestyle: Elevate the head of her bed 6–8 inches and maintain a healthy weight to reduce abdominal pressure. Stress reduction techniques (e.g., meditation, prayer, singing, nature walks, focusing on self) can help lower the overstimulation of the vagal nerve, which can worsen GERD.
  3. Support Asthma (If Present):
    • Monitor Respiratory Symptoms: If asthma is confirmed, track symptoms (e.g., wheezing, shortness of breath) alongside GERD management.
      A 2023       Medicina study suggests treating GERD can improve asthma control in 30–80% of cases.

    • Probiotics and SCFAs: Probiotics that increase SCFA production (e.g., butyrate) may reduce airway inflammation, as shown in a 2023 Mucosal Immunology study.
    • Avoid Triggers: Minimize exposure to allergens or irritants (e.g., dust, pollen) that could exacerbate asthma, especially if GERD-induced microaspiration is a factor.
  4. Monitoring and Testing:
    • Track Symptoms: Use a journal to monitor GERD (heartburn, regurgitation), gut symptoms (bloating, Candida-related issues), and asthma (if present) over 4–8 weeks. Note improvements with L-glutamine, probiotics, and diet.
    • Functional Testing: If GERD or dysbiosis persists, suggest:
      • SIBO Testing: Breath tests to rule out SIBO, common in PPI users and linked to GERD.
      • H. pylori Testing: H. pylori can exacerbate GERD and dysbiosis.
      • Comprehensive Stool Analysis: To assess gut microbiome diversity and Candida levels.
      • Nutrient Levels: Check B12, iron, and zinc, as PPI-induced low HCl may cause deficiencies, worsening dysbiosis.
    • Thyroid Check: Ensure Synthroid dosing is optimal (via TSH, T3, T4 tests), as hypothyroidism can slow gut motility, worsening dysbiosis and GERD.
  5. Long-Term Strategy:
    • Gradual PPI Reduction: Work with the doctor to explore PPI alternatives if GERD stabilizes, as prolonged use may perpetuate dysbiosis and Candida issues. A 2023 AGA Clinical Practice Update recommends multidisciplinary evaluation for extraesophageal GERD symptoms to avoid over-reliance on PPIs.
    • Sustain Gut Healing:
      – Continue L-glutamine (15g/day) for 8–12 weeks, then reassess.
      – Add zinc carnosine (75–150mg/day with meals) or collagen (10–20g/day in water) to further support gut lining repair, discuss these additions with your doctor before taking them.
    • Reassess Candida: After 8 weeks, evaluate Candida symptoms (e.g., bloating, fatigue) to determine if antifungal supplements (e.g., caprylic acid) or medications are needed, under medical guidance.

Conclusion

Recent research (2023–2025) confirms that gut dysbiosis, driven by factors like PPI use and Candida overgrowth, exacerbates GERD and potentially asthma via the gut-lung axis.
Dysbiosis promotes systemic inflammation, weakens the LES, and increases airway reactivity, while GERD worsens asthma through microaspiration and vagal reflexes.
In our client’s case, the key steps are:
– Continuing L-glutamine (5g three times daily),
– Adopting an anti-Candida diet,
– Adding probiotics and reviewing PPI use with the doctor.
These interventions address dysbiosis and GERD, potentially improving asthma (if present) and overall gut health.
– Monitor symptoms and consider functional testing if progress stalls.

Source: Grok XAI

Read more about the effects of Apple Cider Vinegar, Stomach Acid and Candida