Leaky Gut Is Real: Here's How to Know If You Have It and What to Do About It
The gut lining is remarkable. It's one cell layer thick, roughly the diameter of a single hair, and it has to do two apparently contradictory things at once: let nutrients through while keeping everything else out. Bacteria, food proteins that haven't been fully broken down, and inflammatory compounds produced by certain gut bacteria need to stay on the gut side. When they don't, the whole system goes into a kind of low-grade alert.
The symptoms don't always look obviously gut-related, which is part of why intestinal permeability is so often missed.
What's Happening in the Gut Wall
The cells lining the intestine are held together by protein structures called tight junctions. Think of them as the mortar between bricks. When these junctions are working well, they control what passes through with precision. When they're compromised, the seal breaks down, and things that shouldn't enter the bloodstream start to do exactly that.
There are two distinct mechanisms by which this happens, and they behave quite differently.
Paracellular permeability is the more common of the two. This is where the tight junctions themselves break down, driven by a protein called zonulin. It triggers a milder inflammatory response and is the mechanism most commonly associated with what's called leaky gut in functional medicine. Gluten, certain bacterial infections, stress, and alcohol are all known zonulin triggers.
Transcellular permeability is more serious. Here, the intestinal cells themselves lose structural integrity. This drives more severe inflammation and isn't associated with zonulin. It's more indicative of significant mucosal damage.
The most problematic scenario is when either of these mechanisms occurs alongside gut dysbiosis (an imbalanced microbiome), because the bacteria that dominate an unhealthy gut produce highly inflammatory compounds called lipopolysaccharides (LPS). When LPS enters systemic circulation, it triggers a significant immune response throughout the body, contributing to joint pain, brain fog, skin flares, fatigue, and over time, the conditions that precede autoimmune disease.
Symptoms That Point to Intestinal Permeability
The signs are wide-ranging, which is exactly why this tends to be attributed to unrelated causes:
Increasing frequency of food reactions, or reactions that seem to be getting more unpredictable
Aches, pains, and swelling throughout the body
Unpredictable abdominal bloating
Frequent distension after eating, regardless of what's been eaten
Intolerance to sugars and starches
Multiple chemical sensitivities, reacting to smells, jewellery, shampoos, detergents, or skincare that previously felt fine
Constant skin breakouts or rashes
A sense that your immune system is overreacting to more and more things
That last cluster, multiple chemical sensitivities, new environmental reactions, skin that's constantly flaring, is often a signal that the immune system has started to lose tolerance. This is a significant moment to intervene. If it continues unchecked, the immune system can begin producing antibodies against zonulin itself, pushing the process further towards autoimmunity.
Testing
There are tests that distinguishing between paracellular and transcellular permeability and to understanding if you have circulating LPS, dysbiosis and inflammatory compounds in your system that shouldn’t be there. These are tests that typically need to be ordered via a registered practitioner, so do get in contact with us if you’d like this arranged for yourself.
What Heals the Gut Lining
This is where Western and TCM thinking converge. In Chinese medicine, rebuilding the gut's integrity is fundamentally about tonifying the Spleen and Stomach qi, restoring the digestive centre's capacity to hold, transform, and protect. Nutritionally, this maps precisely onto what the research supports.
The core of any permeability repair protocol focuses on regulatory T cells (T-regs), the immune system's peacekeeping cells. They restore tolerance and calm an overactive inflammatory response. Three things are critical for T-reg function: vitamin A, vitamin D, and glutathione.
A diverse microbiome is equally important. Short-chain fatty acids (SCFAs), the compounds produced when gut bacteria ferment fibre, directly feed the intestinal lining cells and are among the most important factors in repairing permeability. This is why microbiome diversity is so central to gut repair. A practical goal is fifteen to twenty different plant foods per day. A useful approach is to chop a wide variety of vegetables, herbs, and seeds, freeze them in ice cube trays, and add a cube daily to soups, stews, or smoothies.
Consistent, steady exercise supports T-reg function too, another reason movement is gut medicine, not just cardiovascular insurance.
Gut healing is layered work. It requires looking at the whole picture: what's driving the permeability, what the microbiome looks like, what the immune system is doing, and what dietary and lifestyle changes will be sustainable long-term. If any of this resonates with your experience, a consultation with me is the best place to start building a clear, personalised plan.