Celiac disease explained: when gluten triggers an autoimmune attack

Not an intolerance, not an allergy - a disease where the immune system attacks the gut itself.

July 30, 2026

"Gluten intolerance." "Gluten allergy." "Celiac." The words get used as if they're interchangeable. They aren't - and celiac disease, in particular, is something very specific and frequently misunderstood.

Celiac disease is not an intolerance, and it's not an allergy. It is an autoimmune disease - and understanding that one fact reframes everything about it.

What celiac disease actually is

In a food intolerance, your body struggles to process a food. In a food allergy, your immune system reacts to a food protein. Celiac disease is a third thing entirely.

In celiac disease, eating gluten - the protein found in wheat, barley and rye - triggers the immune system to attack the body's own small intestine.¹ It's not the gluten that does the damage directly. It's your own immune system, mistakenly turning on your own tissue, with gluten as the trigger. That's what "autoimmune" means - and it's what sets celiac apart from everything it gets confused with.

The mechanism: how gluten triggers the attack

The chain of events is well mapped. When gluten is digested, it leaves behind peptide fragments. An enzyme in the gut called tissue transglutaminase modifies those fragments in a way that makes them bind tightly to specific immune molecules - HLA-DQ2 or HLA-DQ8 - on the surface of immune cells.²

That binding switches on gluten-specific T cells, which - together with other immune cells and inflammatory pathways - drive an attack on the cells lining the small intestine.² The body also produces tell-tale antibodies, including anti-tissue-transglutaminase (anti-tTG) antibodies, which is how the disease can be detected in blood.

Villous atrophy: the real, measurable damage

Here's the part that makes celiac fundamentally different from gluten sensitivity.

The lining of your small intestine is carpeted in villi - tiny finger-like projections that hugely increase the surface area available to absorb nutrients. In active celiac disease, the immune attack flattens them. This is villous atrophy: the hallmark of the disease.²

Flattened villi mean far less surface for absorption - so nutrients pass through under-absorbed. That structural damage is genuine and visible: it can be seen on a biopsy. Non-celiac gluten sensitivity, by contrast, causes symptoms but not this autoimmune destruction. Same trigger food; completely different consequence.

The genetics: necessary, but not sufficient

Celiac has a clear genetic basis - it occurs almost exclusively in people who carry the HLA-DQ2 or HLA-DQ8 genes.

But here's the twist: those genes are common. Around 30-40% of the general population carries them - while only about 1% of people develop celiac disease.² So the genes are necessary for celiac, but nowhere near sufficient. They load the gun; something else - still not fully understood - pulls the trigger. It's why celiac can appear at any age, sometimes after decades of eating gluten with no problem.

It's not just a gut disease

Because celiac damages nutrient absorption, its effects reach far beyond digestion. Alongside the classic gut symptoms - chronic diarrhoea, bloating, weight loss - it commonly shows up as iron-deficiency anaemia, persistent fatigue, reduced bone density, a specific intensely itchy skin rash (dermatitis herpetiformis), and neurological symptoms.³

Crucially, some people have few or no obvious gut symptoms at all - so-called silent celiac. That's a major reason the condition is widely under-recognised and often takes years to identify.⁴

Celiac vs gluten sensitivity vs wheat allergy

	Celiac disease	Non-celiac gluten sensitivity	Wheat allergy
Type	Autoimmune	Not autoimmune, not allergy	Immune (IgE) allergy
Damage to the gut	Yes - villous atrophy	No structural damage	No structural damage
Detectable on tests	Yes - antibodies, biopsy	No specific test	Yes - allergy testing
Trigger	Gluten	Possibly fructans, ATIs or gluten	Wheat proteins

This is why the distinction is more than semantics: only celiac involves ongoing autoimmune damage, which is exactly why it has to be identified and taken seriously rather than self-managed by guesswork.

How it's identified

Celiac disease is identified through specific anti-tTG (and related) antibody blood tests, usually confirmed with a small-intestine biopsy that looks for villous atrophy.¹

One scientifically important detail: these tests only work while you are still eating gluten. Going gluten-free first allows the gut to heal and the antibodies to fade, which can hide the disease. So it's worth knowing this before removing gluten - the order matters.

Because gluten is what drives the autoimmune attack, living with diagnosed celiac means complete, lifelong avoidance of it - that isn't a preference, it's the nature of the condition.

Where Triggerbites fits in

Triggerbites isn't a substitute for celiac diagnosis - celiac is identified medically, and gluten is its known trigger. But tracking is genuinely useful around it, in two ways.

First, before a diagnosis: if you have unexplained gut and whole-body symptoms, logging them builds a clear, documented picture to take to a doctor - while you're still eating gluten, when it counts.

Second, with diagnosed celiac: many people on a strict gluten-free diet still have symptoms - from trace cross-contamination, from hidden gluten, or from the other intolerances that commonly ride alongside celiac, like lactose or FODMAP issues following gut damage. Triggerbites helps catch those hidden exposures and untangle the overlapping triggers.

Log like you're texting - plain language, not database searches

Automatic ingredient breakdown - we parse your entries into the basic components so you don't have to

Built-in chemical tagging - FODMAP, histamine, salicylates, oxalates ++ more compounds flagged automatically

Multi-window pattern recognition - correlations across same-day, next-day, and multi-day windows

Reports you can share - something to take to a doctor or dietitian

For the related conditions, see is it really gluten? Non-celiac gluten sensitivity and food allergy or food intolerance?

Live, love, log. 🧡

References

1
StatPearls, NCBI Bookshelf "Celiac Disease"NCBI Bookshelf
2
Frontiers in Immunology "Interplay Between Gluten, HLA, Innate and Adaptive Immunity Orchestrates the Development of Coeliac Disease", 2021Frontiers
3
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) "Celiac Disease"NIDDK
4
Celiac Disease Foundation "What is Celiac Disease?"Celiac Disease Foundation