The Real Reason Behind Food Sensitivities — And How to Fix Them at the Root
Food sensitivities have become one of the most confusing and frustrating issues people deal with today. One week you’re fine, the next week you react to foods you’ve eaten your whole life. Add in a food sensitivity test that lists 20–40 “trigger foods,” and it’s easy to feel like your body is rejecting everything.
But here’s the truth most people never hear:
In the vast majority of cases, food sensitivity isn’t about the food.
It’s a sign of underlying gut dysfunction — specifically the gut barrier and the gut microbiome.
Once you understand what’s really going on inside the gut, the symptoms suddenly make sense — and so does the path to healing.
1. Your Gut Barrier: The System That Keeps You Safe
Your gut lining is one of the most powerful protective systems in your entire body. The cells in the gut lining are held together by “tight junctions,” which act like tiny gates. Their job is simple:
Let properly digested nutrients through
Keep everything else inside the digestive tract where it belongs
But stress, poor sleep, blood sugar spikes, alcohol, antibiotics, ultra-processed foods, and chronic inflammation can all weaken these tight junctions. When this happens, the gut becomes more permeable — often called increased intestinal permeability or “leaky gut.”
What does this mean for food sensitivity?
Undigested food particles can slip through the weakened barrier and enter the bloodstream. Your immune system doesn’t recognise these larger particles, so it flags them as “foreign” and mounts a response.
You feel this as:
Bloating
Fatigue
Brain fog
Headaches
Rashes or skin issues
IBS-like symptoms
Joint pain
This immune reaction has nothing to do with the food being “bad” — it means the gut barrier isn’t doing its job.
2. The Gut Microbiome: The Inflammation Amplifier
Running alongside the gut barrier is your gut microbiome — the trillions of microorganisms that influence digestion, immunity, mood, and inflammation.
When beneficial bacteria are thriving, they produce short-chain fatty acids like butyrate that:
Strengthen the gut lining
Reduce inflammation
Support the immune system
But when the microbiome becomes imbalanced (a state called dysbiosis) — from stress, medications, poor diet, or infections — harmful bacteria increase. These bacteria produce inflammatory compounds that weaken the gut barrier even more.
The result?
A more inflamed gut + a more reactive immune system = more food sensitivities.
This is why two people can eat the same meal and have completely different reactions. The difference isn’t the food — it’s the microbiome.
3. Why Food Sensitivity Tests Are Often Misleading
Many tests measure IgG antibodies. IgG goes up when the gut is inflamed — not when you have a true allergy or intolerance.
So when a test shows a long list of “reactive foods,” it’s not diagnosing permanent sensitivities.
It’s telling you the gut needs healing.
As the gut barrier repairs and the microbiome rebalances, IgG responses typically drop, and foods that once caused issues become well tolerated again.
4. How to Heal the Gut Barrier (Food-First Approach)
Collagen & Gelatin (for repair)
These support the structural integrity of the gut lining.
Food sources: bone broth, slow-cooked meats, oxtail, gelatin-rich cuts.
Zinc (for tight junction strength)
Zinc is essential for repairing intestinal tissue.
Food sources: beef, lamb, eggs, oysters.
Omega-3s (for inflammation control)
EPA calms immune overactivity in the gut.
Food sources: salmon, mackerel, anchovies, sardines, chia, flax.
5. Rebalancing the Microbiome (Your Microbial Toolkit)
Polyphenols (feed beneficial bacteria + reduce inflammation)
Polyphenols act like “fertiliser” for good bacteria.
Top sources: berries, olive oil, dark chocolate, green tea, turmeric, oregano, rosemary, red cabbage.
Prebiotic Fibre (builds butyrate + strengthens the gut lining)
Prebiotics feed beneficial bacteria that produce gut-healing compounds.
Top sources:
Asparagus
Leeks, onions, garlic
Chicory root
Jerusalem artichokes
Flaxseed, chia seed
Cooked-and-cooled potatoes or rice (resistant starch)
6. Lifestyle Factors That Matter More Than People Think
Healing the gut isn’t just about food. Your gut barrier responds directly to:
Blood sugar balance — high spikes weaken the gut lining
Stress levels — cortisol increases permeability
Sleep — most gut repair happens overnight
Proper chewing — reduces digestive stress
Small shifts here can make a big difference in symptoms.
Final Thoughts: You Don’t Need to Fear Food
Food sensitivities can feel overwhelming, but they are not a life sentence. They are simply a message from your gut that the barrier and microbiome need support.
When you repair the gut, calm inflammation, and restore microbial balance, your immune system becomes less reactive — and foods that once triggered symptoms become part of your diet again.
