How do you fix leaky gut? You identify the specific driver behind it — SIBO, dysbiosis, chronic stress, or dietary irritants — and remove that driver before attempting to repair the gut lining. A 7-step protocol (remove, replace, repopulate, repair, reinoculate, rebalance, retest) is the clinical standard, but sequence matters: repairing a lining while the driver is still active produces temporary results at best. Below is exactly how that works.
Quick Answer
Leaky Gut — What You Need to Know
- Intestinal permeability ("leaky gut") occurs when the gut lining becomes compromised, allowing undigested particles and bacterial fragments to enter the bloodstream
- Symptoms extend well beyond the digestive system — fatigue, brain fog, skin conditions, joint pain, and food sensitivities are common systemic presentations
- It is measurable through functional stool and urine testing, and identifiable on a comprehensive GI Microbiome Map
- The most common drivers are dysbiosis, SIBO, chronic stress, dietary irritants, NSAIDs, and alcohol
- A 7-step gut repair protocol — remove, replace, repopulate, repair, reinoculate, rebalance, retest — is the clinical standard in naturopathic practice
- Individual presentations vary considerably; the right protocol depends on identifying which drivers are most active in your specific case
In this article
Most people who come to see me about gut health don't come in saying "I think I have leaky gut." They come in exhausted, bloated, reacting to foods that never bothered them before, with skin that keeps breaking out and a brain that won't cooperate. Some have seen multiple GPs and specialists. Some have been told their tests are normal. Some have been managing symptoms with antihistamines, probiotics from the supermarket, and a growing list of foods they've eliminated.
What they have in common — almost without exception — is a gut lining that isn't doing its job.
Intestinal permeability, commonly called leaky gut, is not a fringe concept. It is a measurable physiological state with a well-documented research base, and it is one of the most consistent underlying findings in patients presenting with complex, multi-system, unexplained symptoms. The challenge is that it rarely announces itself with clear digestive symptoms. It hides in fatigue, skin reactions, mood changes, and a food sensitivity list that keeps getting longer.
What Is Leaky Gut?
The intestinal lining is a single layer of epithelial cells joined by tight junction proteins — structures that act as a selective barrier, allowing nutrients to pass through while keeping undigested food particles, bacterial fragments, and toxins out of the bloodstream.
When those tight junctions break down — through inflammation, dysbiosis, dietary irritants, stress hormones, or mechanical damage — gaps open in the lining. Substances that should remain in the gut now pass directly into circulation. The immune system encounters these as foreign particles and mounts a response. That response is not localised to the gut. It is systemic.
This is the mechanism behind why leaky gut produces symptoms across multiple body systems simultaneously. The gut is where the problem starts. The symptoms appear everywhere else.
What the research says
Intestinal permeability is well-established in the peer-reviewed literature and is recognised as a contributing factor in inflammatory bowel disease, coeliac disease, type 1 diabetes, non-alcoholic fatty liver disease, rheumatoid arthritis, and numerous neurological conditions. Research published in Frontiers in Immunology describes the intestinal barrier as "a critical interface between the external environment and the internal milieu" whose dysfunction underpins a wide range of chronic inflammatory conditions. This is not a diagnosis in the traditional sense — it is a physiological state that contributes to or worsens other conditions.
Symptoms of Intestinal Permeability
Leaky gut is a multi-system condition. Symptoms extend well beyond digestive discomfort, which is why it is so frequently missed on standard investigation. The presentation that should raise clinical suspicion isn't a single symptom — it's a pattern.
The clinical pattern — do you recognise this?
- Bloating, gas, or abdominal discomfort that worsens after eating — often without an identifiable trigger food
- A food sensitivity list that keeps expanding — foods you previously tolerated now cause reactions
- Persistent fatigue that doesn't improve with adequate sleep
- Brain fog — difficulty concentrating, slow word retrieval, mental heaviness
- Skin conditions — eczema, acne, rosacea, or unexplained rashes that fluctuate with diet and stress
- Joint pain or muscle aches without a clear musculoskeletal cause
- Mood changes — anxiety, low mood, or irritability linked to dietary patterns
- Frequent illness or slow recovery — immune dysregulation
- Histamine reactions — flushing, headaches, hives in response to fermented or aged foods
- Normal blood tests — standard pathology returns unremarkable despite significant symptoms
The expanding food sensitivity list is clinically significant. It doesn't mean more foods are genuinely problematic — it means the gut lining is increasingly unable to contain the immune consequences of ordinary dietary antigens. As permeability worsens, the threshold for immune reactivity drops. The list gets shorter not because the foods changed, but because the barrier did.
If this symptom pattern sounds familiar and standard testing hasn't given you answers, gut permeability may be worth investigating. A GI Microbiome Map measures gut barrier markers directly — a free discovery call clarifies whether it's the right starting point for you.
Talk to Domenic about your gut symptoms →Root Causes — What's Actually Driving It
Leaky gut is not a primary diagnosis in itself — it is a consequence of one or more identifiable drivers. Treating it without identifying those drivers is why many gut repair protocols produce temporary improvement followed by relapse. The following are the most clinically significant causes in order of frequency.
The gut microbiome is not passive. Certain bacterial species produce short-chain fatty acids (SCFAs) — particularly butyrate — that directly nourish colonocytes (the cells lining the gut) and maintain tight junction integrity. When beneficial SCFA-producing bacteria are depleted and pathogenic or opportunistic species overgrow, butyrate production drops. Tight junctions lose their structural support. The barrier weakens.
Dysbiosis also produces LPS (lipopolysaccharide) from gram-negative bacterial cell walls — one of the most potent activators of the innate immune system. When gut permeability is increased, LPS crosses into circulation and triggers a systemic inflammatory cascade. This is the mechanism connecting gut dysbiosis to fatigue, brain fog, and systemic inflammation in conditions well beyond the digestive tract.
SIBO occurs when bacteria migrate from the large intestine into the small intestine, where they ferment carbohydrates, produce gas, and directly damage the mucosal lining. The small intestine is where nutrient absorption occurs and where the vast majority of dietary iron is taken up. SIBO disrupts both simultaneously — producing malabsorption, nutrient deficiency, and gut permeability together.
SIBO is a significant and frequently missed driver of leaky gut. Standard GP investigations do not test for it. A lactulose or glucose breath test identifies the presence of bacterial overgrowth, and a comprehensive stool analysis identifies the microbial landscape driving it.
The gut-brain axis is bidirectional. Chronic psychological and physiological stress directly increases intestinal permeability through corticotropin-releasing hormone (CRH) — a stress hormone that activates mast cells in the gut wall, triggering inflammatory mediator release and tight junction disruption. This is why stress reliably worsens digestive symptoms, food sensitivities, and gut-related fatigue — even when diet hasn't changed.
In clinical practice, patients who have addressed diet and supplements without addressing stress physiology consistently see partial improvement. The gut cannot heal in a chronically activated nervous system.
Several dietary components have documented effects on gut barrier integrity:
- Gluten (gliadin): Research by Dr Alessio Fasano established that gliadin stimulates the release of zonulin — a protein that regulates tight junction permeability — in all individuals, not only those with coeliac disease. The magnitude of response varies, but the mechanism is universal.
- Alcohol: Directly increases intestinal permeability through acetaldehyde-mediated tight junction disruption and contributes to dysbiosis through its antimicrobial effects on beneficial bacteria.
- NSAIDs: Non-steroidal anti-inflammatory drugs inhibit COX enzymes that produce prostaglandins essential for maintaining the gut mucosal layer. Even short-term NSAID use measurably increases intestinal permeability in healthy adults.
- Highly processed foods: Emulsifiers including polysorbate 80 and carboxymethylcellulose — common in packaged foods — have been shown to disrupt the mucus layer and alter microbiome composition in preclinical and some human studies.
The relationship between leaky gut and autoimmune conditions runs in both directions — compromised gut barrier integrity is thought to be a contributing factor in autoimmune onset through exposure of the immune system to dietary antigens; and autoimmune conditions including Hashimoto's thyroiditis increase gut permeability through inflammatory mechanisms. Hormonal changes in perimenopause also affect gut microbiome composition and barrier function.
How Intestinal Permeability Is Tested
One of the main reasons leaky gut goes unidentified is that standard pathology panels don't assess it. The following functional tests provide clinically useful information about gut barrier integrity, microbiome health, and digestive function.
Why testing changes outcomes
Treating leaky gut without testing is like repairing a roof without finding where the leak is. The protocol varies significantly depending on whether the primary driver is SIBO, dysbiosis, candida overgrowth, or barrier damage from NSAIDs and stress. Testing identifies the driver — which determines the sequence and selection of interventions. The GI Microbiome Map is the most informative single investigation for most patients presenting with leaky gut.
Clinical Case Study — Composite Anonymised Patient
"I'd been told everything was normal for three years."
Sarah, 34, presented with a two-year history of bloating after almost every meal, fatigue that hadn't improved despite 8 hours of sleep, eczema that had been well-controlled for a decade but was now flaring constantly, and a growing list of food reactions. She'd had a standard blood panel, coeliac serology, and a gastroscopy — all normal. She was taking a probiotic from the supermarket and had eliminated gluten, dairy, and eggs without meaningful improvement.
Her GI Microbiome Map revealed significantly elevated zonulin (a direct marker of intestinal permeability), severely depleted beneficial Lactobacillus and Bifidobacterium species, elevated Klebsiella pneumoniae, and markedly reduced secretory IgA — indicating compromised mucosal immune defence. Her organic acids test showed dysregulated arabinose (a marker of yeast overgrowth) and impaired mitochondrial function markers. A SIBO breath test confirmed hydrogen-dominant SIBO.
This wasn't a problem with the foods she was avoiding. It was a problem with the gut environment that was driving her reactions to them.
At six months, her repeat GI Microbiome Map showed normalised zonulin, restored secretory IgA, and a significantly improved microbiome profile. She reintroduced gluten, dairy, and eggs without reaction. The foods were never the problem.
Composite case for educational purposes. Individual results vary. This is not a treatment guarantee.
The 7-Step Gut Repair Protocol
The 7R protocol is the clinical standard for gut repair in naturopathic and functional medicine. Sequence matters — attempting to repopulate a gut that hasn't been cleared of pathogens, or repairing a lining while the drivers are still active, produces incomplete results. Each step builds on the last.
A personalised gut repair protocol begins with identifying which of the seven drivers is most active in your case. That requires testing — not assumption. A free discovery call identifies the right starting point.
Book a free gut health review →Diet for Gut Healing
Diet is a meaningful component of gut repair — but it works differently depending on the stage of healing. Trying to repopulate the microbiome with fermented foods while SIBO is active, for example, can worsen symptoms significantly. The dietary guidance below is for the repair and maintenance phases — after primary pathogen removal.
Foods That Support Gut Barrier Integrity
- Bone broth: Provides collagen, glycine, and glutamine — direct structural support for the gut lining
- Cooked vegetables: Easier to digest than raw; provide prebiotic fibre for microbial diversity
- Oily fish (salmon, sardines, mackerel): Omega-3 fatty acids reduce gut inflammation and support mucosal integrity
- Fermented foods (once SIBO is cleared): Kefir, kimchi, sauerkraut, miso — support Lactobacillus and Bifidobacterium populations
- Blueberries and polyphenol-rich fruits: Polyphenols support microbial diversity and reduce inflammatory cytokine production
- Extra virgin olive oil: Oleocanthal has anti-inflammatory properties; supports beneficial gut bacteria
- Resistant starch (cooled rice, green banana, cooked and cooled potato): Selectively feeds SCFA-producing bacteria
Foods to Minimise During Active Gut Repair
- Alcohol — directly damages tight junctions
- Refined sugar and processed carbohydrates — feed pathogenic and yeast species
- Emulsifiers in packaged foods — disrupt the mucosal layer
- Gluten-containing grains during the removal phase — particularly where zonulin is elevated
- NSAIDs where avoidable — consider paracetamol instead; discuss alternatives with your GP
On elimination diets
Extensive elimination diets are frequently used — and frequently overused — in gut health management. Removing 10 foods does not heal the gut lining. It temporarily reduces the antigenic load on an already-compromised barrier. The goal is to repair the barrier so that previously reactive foods can be tolerated again. If your safe food list is getting shorter, that is a sign the barrier is worsening — not that more foods need to be eliminated.
Important — medical disclaimer
This article is for general educational purposes and does not constitute medical advice. Significant digestive symptoms — including unexplained weight loss, rectal bleeding, persistent severe abdominal pain, or symptoms that are worsening rapidly — require urgent GP assessment to exclude serious conditions. Naturopathic gut health support is intended to complement, not replace, conventional medical care.
Related reading — conditions driven by gut permeability
Your gut health is fixable — with the right sequence
Normal Blood Tests Don't Rule Out Gut Permeability. The Right Testing Does.
A GI Microbiome Map measures zonulin, secretory IgA, microbiome composition, inflammatory markers, and digestive function — all in one test. Results are reviewed with Domenic in a comprehensive consultation. You leave with a protocol built around your specific drivers, not a generic gut health plan. A free 20-minute discovery call is the right starting point.
Frequently Asked Questions
About the Author
Domenic Pisanelli, BHSc Naturopathy, is a Melbourne naturopath with 25 years of clinical experience specialising in gut health, chronic fatigue, autoimmune conditions, and women's hormonal health. He uses advanced functional testing including the GI Microbiome Map and Organic Acids Test through NutriPath (NATA #20770) to identify the specific drivers of gut dysfunction in each patient. He practises at Vital Health and Natural Medicine, 195A Sunshine Ave, Kealba VIC 3021, and offers telehealth consultations nationally. ATMS registered. This article is for general educational purposes only and does not constitute medical advice.
