Helen Edwards, Nutritional Therapist, New Roots Herbal
Clinicians and therapists across the UK and Europe are increasingly encountering clients with chronic, low-grade digestive complaints, such as bloating, erratic bowel movements, unexplained fatigue, nutrient depletion, skin reactions and persistent food intolerances. Intestinal parasites such as Giardia lamblia, Blastocystis hominis and even candidiasis are often identified as contributing to this picture. Yet the more important clinical question may not be how to treat these, but why the gut allowed them to colonise in the first place.
The Root Cause: Compromised Lines of Defence
Looking through a functional medicine lens immediately draws attention to the health of the terrain rather than the pathogens. A resilient gastrointestinal tract possesses multiple layers of innate protection, and when any of these lines of defence become compromised, the risk of pathogenic colonisation, whether by protozoa, opportunistic yeast or dysbiotic bacteria, rises dramatically.
The three most overlooked lines of defence are gastric acid,bile production and the diversity of the microbiome. Adequate stomach acid (pH < 3) provides a powerful antimicrobial barrier: it denatures parasitic cysts, inhibits bacterial overgrowth and triggers the cascade of downstream enzymatic activity needed for proper digestion. When gastric acid is insufficient from chronic stress, proton pump inhibitor use, H. pylori infection, or simply ageing – Giardia cysts, Candida spores and pathogenic bacteria that would otherwise be neutralised in the stomach pass through intact and colonise the small intestine. Similarly, bile secretion from the gallbladder serves as a natural antiparasitic and antifungal agent: bile acids disrupt the lipid membranes of protozoa, inhibit Candida biofilm formation and maintain an environment hostile to bacterial dysbiosis. Reduced bile flow, common in clients with sluggish liver function, low-fat diets, or prior cholecystectomy (removal of the gallbladder) is a clinically overlooked factor for both parasitic colonisation and intestinal Candida overgrowth.
The Microbiome: A Third Line of Defence
If gastric acid and bile represent the gut’s chemical defences, the commensal microbiome represents its ecological defence, and arguably the most sophisticated of the three. A diverse, well-populated microbiome creates conditions that are simply inhospitable to parasitic colonisation, Candida overgrowth and pathogenic bacteria, through mechanisms that operate continuously and simultaneously throughout the intestinal tract.
Commensal bacteria physically compete with pathogens for mucosal adhesion sites – there is no room for Giardia trophozoites (the active, feeding form of the parasite) or Candida hyphae (invasive thread-like filaments produced when the yeast turns pathogenic) to anchor when there is a diverse microflora that already occupies the space. Strains such as Lactobacillus acidophilus and Bifidobacterium longum produce organic acids that lower the pH of the gut environment, making it unfavourable for pathogenic bacteria and fungi to survive. Bifidobacterium breve has demonstrated specific inhibitory activity against Candida, offering a further layer of antifungal protection within a healthy balanced microbiome.
Unfortunately, this third line of defence is the one most vulnerable to insult by the modern living environment. Antibiotic use, ultra-processed diets, chronic psychological stress, environmental toxin exposure and even proton pump inhibitor use all selectively deplete the commensal flora, leaving it open to opportunistic pathogens. This is why even clients with no exotic travel history, and no obvious risk factor are still presenting with Giardia and Blastocystis – their gut ecology has become compromised. Restoring microbiome numbers and diversity is therefore not just a post-therapy step; it is a primary preventive strategy in clinical practice.
In practice, New Roots Herbal’s Pro-Boulardii Plus combines the clinically researched transient yeast Saccharomyces boulardii – proven to directly inhibit intestinal parasites and Candida colonisation and enhance secretory IgA – with twelve resident probiotic strains including Lactobacillus rhamnosus, Bifidobacterium longum and Lactobacillus acidophilus, delivering broad-spectrum microbiome restoration and targeted antimicrobial defence in a single formula.
Restoring the Gut Barrier: The Final Layer of Recovery
Once the pathogenic load has been addressed and microbiome restoration is underway, attention turns to the intestinal barrier itself. The gut epithelium – a single layer of cells separating the gut lumen from the systemic circulation – is both the primary target of parasitic damage and the ultimate measure of a successful recovery. Parasites such as Giardia disrupt the tight junction proteins that hold epithelial cells together, while Candida hyphae can penetrate the mucosal layer directly, driving localised inflammation and increasing intestinal permeability. The clinical consequences are well recognised: food reactivity, systemic inflammation, immune dysregulation, skin conditions and on-going fatigue and cognitive symptoms long after the original infection has resolved.
In most cases, active gut healing is best introduced after the pathogenic burden has been addressed. Attempting to rebuild a mucosal lining while parasites or Candida continue to damage it is somewhat counterproductive. The exception is the client presenting with significantly compromised barrier function from the outset: severe food reactivity, markedly elevated zonulin, a history of prolonged antibiotic use or inflammatory bowel disease. In these cases, mucosal support should come first or run concurrently during the cleansing and biofilm-disruption phase before antimicrobials come into play. Nourishing a stressed gut so it has the structural resilience to tolerate and respond to therapy, rather than being further destabilised by it.
This is where targeted nutritional support becomes essential. New Roots Herbal’s GI Repair was formulated specifically for this stage of recovery. L-Glutamine fuels the regeneration of enterocytes and helps restore tight junction integrity, while Zinc Carnosine supports the slower work of epithelial healing. Deglycyrrhizinated liquorice (DGL) and Slippery Elm nourish the protective mucus layer that parasites and dysbiosis compromise, and N-Acetyl Glucosamine reinforces the mucosal integrity that chronic dysbiosis progressively erodes. Together, these nutrients address the gut not just as a site of infection, but as a tissue that needs rebuilding.
Parasites and Candida do not thrive in a healthy gut, and the most long-lasting clinical outcomes come not from therapy alone, but from rebuilding the terrain that made colonisation possible in the first place.
References
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