This is one of the first things I work to help new clients understand – because without it, people get stuck in an exhausting and fruitless loop.
Trying to identify the offending food. Eliminating one thing, then another. Keeping food diaries. Running allergy tests. And yet the pattern remains inconsistent, confusing, and demoralising.
Here’s what’s actually going on.
If you’ve ever eaten the exact same food and had it flare your symptoms one day – then eaten it again another day with no reaction at all – that inconsistency is not random. It is one of the most important clinical clues you can give me. Because it tells us clearly that the food is not the root cause. It is a symptom of something deeper: gut-brain axis dysfunction and vagus nerve dysregulation.
What’s Really Going On
Your gut and brain are in constant, real-time communication via the vagus nerve. This nerve regulates digestion, immune signalling, and your gut’s tolerance to food. When you are under stress – even low-level, chronic, or entirely subconscious stress – this communication becomes dysregulated, and digestion is one of the first things to suffer.
Here is what that dysregulation looks like in the gut:
- Reduced digestive secretions – less stomach acid, bile, and enzymes available to properly break down food
- Altered motility – for some, stress slows transit time, producing constipation; for others it accelerates it, producing urgency and loose stools
- An inflamed mucosal lining – where nerve endings become hypersensitive, producing what we call visceral hypersensitivity
- Increased gut permeability – or leaky gut, where particles that should remain in the digestive tract cross into circulation and trigger an exaggerated immune response
Your Body in Survival Mode
When the brain perceives threat – whether that threat is physical, emotional, relational, or operating entirely below conscious awareness – the body shifts into survival mode. Stress hormones surge. Blood flow is redirected away from the digestive tract toward the muscles. Sugar is dumped into the bloodstream to fuel a fight-or-flight response. And digestion, because it is not a priority in a survival state, effectively shuts down.
So even if what you’re eating is perfectly healthy, your gut simply is not primed to handle it in that moment. The food isn’t being broken down, absorbed, or tolerated properly – not because the food is inherently the problem, but because your nervous system is prioritising survival over digestion.
That is why the same food causes symptoms one day and is completely fine the next. The food didn’t change. Your nervous system state did.
The Role of Stomach Acid and Digestive Enzymes
One of the most overlooked pieces of this puzzle is the role of hydrochloric acid (HCL) and digestive enzymes. When the nervous system is dysregulated and the body is in a stress response, production of both drops significantly. This means food is not being broken down adequately – proteins in particular – before it moves further through the digestive tract. The result is fermentation, bloating, reactivity, and the appearance of a food intolerance that may not be a true intolerance at all.
Supporting your body’s natural production of HCL and digestive enzymes is one of the most practical and impactful things you can do alongside nervous system work. I’ve put together a free practical guide that walks through exactly how to do this – from the cephalic stage of digestion and the role of sunlight and protein, through to bitter foods, zinc, electrolytes, herbal bitters, and targeted supplementation.
Download the free Practical Guide: Optimising HCL & Digestive Enzyme Production →
Why the Question Changes Everything
This is why, with many of my clients, while we absolutely need to address dysbiosis and treat the gut directly, I place equal – if not greater – emphasis on restoring nervous system balance. Because healing the gut starts with calming the brain.
In practice, that means:
- Supporting deep sleep and circadian rhythm regulation
- Correcting the nutrient deficiencies that impair neurotransmitter function
- Incorporating breathwork and gut-directed hypnotherapy to gradually rewire gut-brain signalling
- Drawing on herbal medicine to calm, repair, regulate, and restore
- Addressing SIBO and gut dysbiosis where present, in the correct sequence
The question that changes everything isn’t “which food is causing this?” It’s “why is my gut reacting to food in the first place?”
Chronic food intolerances and sensitivities are some of the most common concerns I hear from clients – and I know how challenging they can be. For many people, these reactions become genuinely debilitating. Eating out becomes a source of fear rather than pleasure. The constant vigilance required to manage symptoms takes a real toll on quality of life.
But food reactions don’t happen in isolation. There are almost always multiple factors at play, which is precisely why a comprehensive, root-cause approach is so important – and why endlessly eliminating foods rarely gets people where they want to go.
By taking a strategic and tailored approach – with the right testing and treatment – you can uncover what is actually driving your sensitivities, begin reintroducing foods, and enjoy eating again without fear.
Food should nourish and delight you. Not cause stress.
