If you have heard the term leaky gut and wondered what it actually means, and whether it might be behind your symptoms, let us walk through it clearly.

What Is Intestinal Permeability?

Your gut lining acts like a protective wall. Its job is to let the good stuff in, such as nutrients and water, while keeping unwanted particles like toxins, bacteria, and undigested food out.

When that barrier becomes more permeable than it should be, larger particles can slip through into the bloodstream. The immune system can then treat them as invaders, which may contribute to inflammation, irritation, and a wide range of symptoms. This is what people commonly refer to as leaky gut.

Why Does It Matter?

Intestinal permeability has been studied for many years and has been linked with a range of gastrointestinal and systemic conditions. Not everyone with these conditions has gut barrier dysfunction, but when it is present it can make symptoms more intense or harder to resolve.

• Crohn’s disease
• Ulcerative colitis
• Irritable bowel syndrome
• Skin and inflammatory conditions
• Some autoimmune and metabolic presentations

What Can Contribute to Leaky Gut?

• A low-fibre, highly processed diet
• Excess alcohol or sugar
• Food additives such as some emulsifiers
• Regular antibiotics, oral contraceptive pill use, or long-term NSAID use
• Chronic stress and poor sleep
• Heavy or intense exercise
• Low vitamin D levels
• Gut infections or illnesses

Common Symptoms

Symptoms can vary from person to person, but common signs include:

• Bloating, gas, diarrhoea, or constipation
• Food sensitivities
• Fatigue or brain fog
• Joint pain or inflammation
• Skin issues such as acne, eczema, or rashes

What Can You Do?

The good news is that the gut lining is resilient and can improve with the right support. Some of my favourite strategies include:

1. Eat more whole plant foods: aim for variety, colour, fibre, and plenty of water.
2. Reduce gut irritants: cut back on alcohol, ultra-processed foods, and unnecessary gut-disrupting medications where appropriate.
3. Use targeted supplements carefully: nutrients and products such as glutamine, zinc, probiotics, or vitamin D may help, but should be tailored to the individual.
4. Manage stress: your nervous system and gut are deeply connected.
5. Recover well after exercise: hydration, fuelling, and sleep matter.

How Long Does Healing Take?

A healthy gut lining can begin repairing quite quickly, but meaningful improvement usually takes time. For many people, that means anywhere from a few weeks to a few months depending on health history, diet, stress, and underlying conditions.

Can You Test for Leaky Gut?

Yes. The Lactulose:Mannitol urine test is widely used to assess intestinal permeability and can give us clear, actionable information to guide your plan.

If you have been struggling with ongoing gut or whole-body symptoms and wondering whether leaky gut could be part of the picture, explore our Leaky Gut Testing and Consult Package or book a consult to discuss the right next step.

References

• Leech R, et al. Intestinal permeability in gastrointestinal and systemic disorders: Current evidence and clinical implications. Frontiers in Nutrition. 2019;6:26.
• Fasano A. Leaky gut and autoimmune diseases. Clinical Reviews in Allergy and Immunology. 2012;42(1):71-78.
• Camilleri M. Leaky gut: Mechanisms, measurement, and clinical implications in functional gastrointestinal disorders. Neurogastroenterology and Motility. 2019;31(10):e13620.
• Bischoff SC, et al. Intestinal permeability: A new target for disease prevention and therapy. BMC Gastroenterology. 2014;14:189.
• Mu Q, Kirby J, Reilly CM, Luo XM. Leaky gut as a danger signal for autoimmune diseases. Frontiers in Immunology. 2017;8:598.
• Hollander D. Leaky gut in clinical practice. Clinical Gastroenterology and Hepatology. 2009;7(11):S12-S14.

Written by Naturopath Chae

It is not always talked about openly, but it matters. Intense exercise can temporarily make the gut more permeable. Here is what that means, why it happens, and when it may need more support.

What Happens to the Gut During Intense Exercise?

During heavy, prolonged, or high-intensity exercise, the body diverts blood away from the gut and toward working muscles. While this supports performance, it also means the gut lining receives less oxygen.

The result is that the tight junctions that normally hold the gut lining together can loosen, making the barrier more permeable for a period of time.

When Is It Most Likely to Happen?

This is usually not an everyday gym-session issue. It is more commonly seen during:

• Marathons and ultramarathons
• Triathlons and Ironman events
• Long-distance cycling
• Intense training in hot or dehydrating conditions

Research suggests many endurance athletes experience some increase in gut permeability during or after prolonged exercise.

Does It Fix Itself?

For most otherwise healthy athletes, yes. This increase in permeability is often temporary and self-limiting. Once you rehydrate, refuel, and recover, the gut lining generally settles again within hours to days.

When Does It Become a Concern?

It becomes more relevant if:

• You notice ongoing digestive symptoms such as bloating, cramping, diarrhoea, or food sensitivities
• You are training hard but recovering poorly
• You already have an underlying gut condition such as IBS, coeliac disease, or IBD

That is often the point where runner’s gut stops being a one-off inconvenience and starts becoming a sign the gut needs support.

Supporting Gut Recovery

• Hydrate well, including electrolytes when appropriate
• Refuel with gut-friendly, anti-inflammatory foods
• Avoid NSAIDs around training and events where possible, as they can worsen gut permeability
• Prioritise rest and sleep, because the gut heals when you do

If symptoms persist, short-term targeted support may help under practitioner guidance. This can include glutamine, zinc carnosine, colostrum, selected probiotics, or deeper gut investigation.

The Key Point

A temporarily leaky gut during intense endurance exercise is often normal and usually nothing to panic about. But if symptoms continue, or if you have an underlying gut condition, it is worth getting support so training does not come at the expense of your gut health.

Because a stronger gut often supports a stronger athlete.

If symptoms keep lingering, you can book a consult or explore our consult and testing packages to investigate what else may be going on.

References

• Lamprecht M, et al. Exercise and gut permeability in endurance athletes. Current Opinion in Clinical Nutrition and Metabolic Care. 2012;15(6):582-587.
• Jeukendrup AE. Nutrition for endurance sports: Marathon, triathlon and road cycling. Journal of Sports Sciences. 2017;29(sup1):S91-S99.
• Leech B, Schloss J, Steel A, et al. Association between increased intestinal permeability and disease: A systematic review and meta-analysis. Neurogastroenterology and Motility. 2019;31(4):e13565.

Written by Naturopath Chae