Disclaimer: This article is for informational purposes only and does not constitute medical advice. Symptoms of gut issues should always be assessed by your GP or a registered health professional.
Leaky gut is one of those health terms that gets dismissed as wellness-industry pseudoscience by some doctors and treated as the root cause of everything by alternative practitioners. Intestinal hyperpermeability — the clinical term — is a real, measurable phenomenon. What is less clear is how often it causes the broad range of symptoms commonly attributed to it, and how much treating it actually helps in people who do not have a diagnosed gut condition.
What Is Intestinal Permeability (Leaky Gut)?
Your intestinal lining is a single layer of epithelial cells joined together by tight junction proteins. These junctions control what passes through the lining into your bloodstream — allowing nutrients through while keeping bacteria, undigested food particles, and toxins out. When these tight junctions become loose or damaged, larger particles can pass through that should not. This is intestinal hyperpermeability.
The condition is well-documented in people with coeliac disease, Crohn’s disease, ulcerative colitis, and other diagnosed gut conditions. It also occurs in response to factors like heavy alcohol use, NSAID overuse, high psychological stress, and certain medications. The more contested question is whether mild permeability changes in otherwise healthy people cause the wide range of symptoms — brain fog, skin issues, autoimmunity, food intolerances — that wellness content often attributes to leaky gut.
Signs That May Indicate Gut Barrier Issues
The following symptoms are associated with gut health issues generally and, in some people, with intestinal permeability specifically. They are non-specific — meaning they have many possible causes — so do not self-diagnose based on this list alone:
- Bloating, cramping, or discomfort after eating that does not resolve
- Multiple food sensitivities that have developed over time
- Chronic fatigue that is unexplained by sleep or other factors
- Skin conditions including eczema, psoriasis, or adult acne
- Brain fog — difficulty concentrating, poor memory, mental fatigue
- Frequent digestive upset with no clear diagnosis
- Autoimmune conditions (permeability is associated with some, though causation is not fully established)
What Actually Damages the Gut Lining
Before reaching for supplements, it is worth addressing the things most often linked to gut barrier damage:
- Chronic NSAID use: Regular ibuprofen and aspirin use is the best-recognised item on this list, and gut lining irritation is a known effect of taking them long-term. Discuss alternatives with your GP if this applies to you.
- Alcohol: Regular drinking is consistently linked to a more permeable gut lining. How much it takes appears to vary a good deal between people.
- Chronic psychological stress: The gut-brain axis is real, and gut symptoms commonly track with periods of stress. Exactly how stress acts on the barrier itself is still being worked out, so treat confident mechanistic explanations with some caution.
- Highly processed diet: Emulsifiers used in processed foods (particularly polysorbate 80 and carboxymethylcellulose) are the usual concern here, largely on the strength of animal work. What that means for people eating them at normal amounts is not settled.
- Antibiotics: Necessary when prescribed, but antibiotic courses disrupt the gut microbiome and can temporarily affect barrier function. Probiotic supplementation during and after a course is worth discussing with your doctor.
Approaches That May Help
L-Glutamine
Glutamine is the primary fuel for intestinal epithelial cells, which is why it turns up in almost every gut-repair formula. Most of the interest in it comes from its use in people with diagnosed gut conditions rather than from anything settled about healthy adults, so treat it as reasonable to try rather than proven. The safety profile is good. Products typically suggest 5g daily in powder form. Here, Radiance (New Zealand-owned, based in Auckland) makes Amino Glutamine, a plain L-glutamine powder: the label suggests one heaped teaspoon (5g) once or twice daily, and says it is not recommended for people at risk of kidney or liver disorders, or for diabetics. It is around NZ$65 for 300g from HealthPost (checked October 2026). GO Healthy’s GO Gut Soothe also contains glutamine, but only 500mg a day, a tenth of that dose, alongside kiwifruit powder.
Zinc Carnosine
Zinc carnosine is a different compound from the zinc in a standard supplement, and it is the form specifically sold for gastric and intestinal lining support. It is also the one item on this list with a proper randomised trial behind it, and that study is worth reading carefully.
Ten healthy volunteers took indomethacin, an anti-inflammatory known to damage the gut lining. On indomethacin alone, gut permeability tripled. With zinc carnosine at 37.5mg twice daily alongside it, permeability did not rise significantly (Mahmood et al., Gut, 2007).
That is a genuine, peer-reviewed, placebo-controlled result in a good journal. It is also ten people, all healthy, protected against a specific drug injury, measured by a laboratory marker rather than by how anyone felt. A promising signal, not proof it repairs an everyday unsettled gut.
Two other things are worth knowing. Zinc carnosine is not a supplement-industry invention — as polaprezinc it has been a prescription medicine in Japan for gastric ulcer since 1994, at 150mg a day (Li et al., 2021). And the dose on the shelf matches the dose in the research: zinc carnosine supplements typically provide 75mg a day, the same as the Mahmood study and half the Japanese prescription dose. A 75mg daily dose also delivers about 16mg of elemental zinc, so count it towards your total zinc intake rather than on top of it.
What does not exist is a systematic review supporting the gut-lining claim. The only meta-analysis we could find on zinc carnosine covers H. pylori eradication rather than the gut lining — three trials, 396 participants, better eradication when it was added to standard triple therapy, and authors who say plainly that “the evidence is still scarce” (Mahmoud et al., Nutrients, 2022). We could not find a standalone zinc carnosine supplement from a New Zealand or Australian brand, so we are not naming one. If you want to try it, talk to your GP or pharmacist first.
Bone Broth
Bone broth contains collagen, gelatin, and glycine, which is the basis for the claim that it supports the gut lining. That claim rests on a tradition of use rather than clinical trials, so we would not put it forward as a treatment. It is a food rather than a supplement, it is safe, it is NZ-relevant (accessible from local butchers and NZ brands like Mitchells Nutrition), and it is a useful dietary addition on those terms. Ready-made bone broth powders are also available on HealthPost from brands such as Nutra Organics.
Probiotics and Prebiotics
A healthy, diverse gut microbiome produces short-chain fatty acids (including butyrate) that directly nourish the gut lining and support tight junction integrity. A quality probiotic combined with prebiotic fibre is one of the more evidence-supported general approaches. See our Best Probiotics NZ guide for specific product recommendations.
Dietary Changes
Increasing dietary fibre, reducing processed food, adding fermented foods (Raglan Food Co coconut yoghurt, kombucha, sauerkraut), and reducing alcohol are the foundational changes with the strongest evidence base — before any supplement is considered. Our complete guide to gut health in NZ covers those foundations in more detail.
What to Be Sceptical About
The leaky gut supplement industry sells a lot of products — many with very little evidence behind them specifically for intestinal permeability. Colostrum, high-dose quercetin, and various herbal blends are marketed aggressively for leaky gut with limited robust human trials. This does not mean they do nothing, but the evidence is thin relative to the marketing claims. Be particularly sceptical of products that claim to cure or fix leaky gut completely — the honest answer is that management is gradual and multi-factorial. Digestive enzymes are often marketed for the same purpose, and our guide to the best digestive enzymes in NZ explains who actually needs them.
The Bottom Line
Intestinal permeability is real, but the evidence for treating non-diagnosed leaky gut in otherwise healthy people is mixed. If you suspect gut issues, the most important first step is a GP assessment to rule out coeliac disease, IBD, and other diagnosed conditions. From there, the foundational approach — reducing known irritants, increasing dietary fibre, adding fermented foods, managing stress, and supporting microbiome diversity with probiotics and prebiotics — has the strongest evidence and the fewest risks. Our guide to the best prebiotic supplements in NZ covers the fibres worth starting with.
Sources
- Mahmood A, FitzGerald AJ, Marchbank T, et al. “Zinc carnosine, a health food supplement that stabilises small bowel integrity and stimulates gut repair processes.” Gut, 2007;56(2):168–175. pubmed.ncbi.nlm.nih.gov/16777920
- Li M, Sun Z, Zhang H, Liu Z. “Recent advances on polaprezinc for medical use (Review).” Experimental and Therapeutic Medicine, 2021;22:1445. spandidos-publications.com/10.3892/etm.2021.10880
- Mahmoud A, et al. Nutrients, 2022;14(19):4126 — systematic review and meta-analysis of zinc carnosine in Helicobacter pylori eradication. pmc.ncbi.nlm.nih.gov/articles/PMC9573391
This article does not contain affiliate links as we do not recommend specific products for diagnosed gut conditions without professional guidance.
