Celiac Disease vs Gluten Intolerance: What's the Real Difference?

Confused about celiac disease vs gluten intolerance? Learn the key differences, symptoms, and why getting the right diagnosis changed my life as a woman over 30.

Giselle Meireles

5/21/20265 min read

I Had No Idea My Body Was Fighting Against Me

For months, I lived in a fog I couldn't explain.

No energy to get through the day. Constant bloating. And a kind of mental blurriness that scared me more than anything else — I would get in my car and completely forget where I was going. Tasks that used to feel simple suddenly felt impossible to focus on.

I was living far from home, in a new country, still finding my feet with the language. I felt lost — not just physically, but in every sense. I didn't know where to start looking for answers.

Eventually, I found a Brazilian doctor here in Australia. I sat down and told him everything I was feeling. He started with a simple blood test — a full blood count — and what he found was alarming: multiple vitamin deficiencies and a ferritin level of just 6. To put that in perspective, ferritin measures iron stores in your body, and a level that low is practically non-existent. He immediately arranged intravenous iron infusions and started me on B12 and Vitamin D supplementation.

A few weeks later, I felt better. But every time my period came, I crashed again — losing blood made everything worse. (A little later I found out I also had a fibroid, but that's a story for another post!)

Two months on, feeling weak again — not as bad as the first time, but still not right — I went back. The blood results were almost identical: ferritin critically low again, vitamins depleted again. But this time, a new symptom had appeared: persistent bloating and gas.

My doctor was intrigued. The pattern wasn't adding up to a simple iron problem. So he ordered an H. pylori test and a full panel of food allergy and intolerance testing to see whether something I was eating was causing all of this.

The result changed my life: my tissue transglutaminase antibody (tTG-IgA) came back at 95 — an extremely high reading. I was celiac.

I sat there in shock. I had never even heard of celiac disease. But the look on my doctor's face told me it was serious. This wasn't something I could manage with a little more care. This was permanent. Everything had to change — for me and for everyone who shares a meal with me.

And yet, as confronting as that moment was, something also made sense for the first time. The exhaustion. The brain fog. The constant crashes. My body had been fighting all along — I just hadn't known what it was fighting against.

I want to be transparent about my own diagnostic journey: the moment I received that blood test result, I immediately changed my diet — I wasn't willing to wait. Two months later, I travelled to Brazil and had a duodenal endoscopy, which is the gold standard for confirming celiac disease. The results left no room for doubt. The damage to my intestinal villi was clearly visible. My gastroenterologist in Brazil confirmed the autoimmune diagnosis without hesitation. Seeing the actual evidence of what gluten had been doing to my body made the permanence of this change very real — and completely non-negotiable.

So What Actually Is Celiac Disease?

Celiac disease is not a food allergy or a preference. It is an autoimmune disease.

When someone with celiac disease eats gluten — a protein found in wheat, barley, and rye — their immune system treats it as a threat and attacks the lining of the small intestine. Over time, this damages the tiny finger-like projections called villi that are responsible for absorbing nutrients. That's why so many celiacs, like me, end up with severe vitamin and mineral deficiencies even if they appear to eat well.

Diagnosis requires two steps: a blood test measuring tTG-IgA antibodies, followed by an endoscopy with biopsy to confirm intestinal damage. It's important not to cut out gluten before testing, as this can cause false negatives.

Celiac disease affects roughly 1 in 70 Australians, and women — particularly those over 30 — are frequently diagnosed late, often after years of unexplained symptoms.

What Is Gluten Intolerance (Non-Celiac Gluten Sensitivity)?

Gluten intolerance, also called Non-Celiac Gluten Sensitivity (NCGS), produces symptoms that can look very similar to celiac disease — bloating, fatigue, brain fog, stomach pain — but with one critical difference: there is no autoimmune response and no measurable intestinal damage.

The mechanisms behind NCGS are still not fully understood. There are no reliable biomarkers to diagnose it directly. Instead, it's diagnosed by exclusion: ruling out celiac disease and wheat allergy first, then observing whether symptoms improve on a gluten-free diet.

People with gluten intolerance may tolerate tiny amounts of gluten with less severe consequences than someone with celiac — but that varies enormously from person to person.

Key Differences at a Glance

Celiac DiseaseGluten Intolerance (NCGS)CauseAutoimmune responseNot fully understoodIntestinal damageYesNoDiagnosisBlood test (tTG-IgA) + endoscopyExclusion of other conditionsStrictness requiredExtremely strict — even traces matterVaries per personLong-term health risks if untreatedYes (anemia, osteoporosis, neurological issues)Less clearly definedGenetic componentYes (HLA-DQ2/DQ8 genes)Possibly

Why Getting the Right Diagnosis Matters

This is where I want to be direct with you: if you suspect either condition, please don't just cut out gluten and hope for the best.

Undiagnosed celiac disease carries real long-term risks — not just nutritional deficiencies, but increased risk of osteoporosis, certain intestinal cancers, infertility, and neurological conditions. Getting an official diagnosis means you have a medical record, can access proper follow-up care, and truly understand the level of strictness your body requires.

For me, the diagnosis explained years of feeling "not quite right." It explained the iron that kept disappearing. The exhaustion that sleep couldn't fix. The brain that felt like it was wrapped in cotton wool.

If I had just assumed I was gluten intolerant and occasionally cheated, the damage would have continued silently.

What to Do If You Suspect You Have Either Condition

Don't remove gluten yet — you need to be eating gluten for the tests to be accurate.
See your GP and ask specifically for a tTG-IgA blood test.
If the blood test is positive, your doctor will refer you for an endoscopy and biopsy to confirm.
If celiac is ruled out but symptoms persist on gluten, discuss Non-Celiac Gluten Sensitivity with your doctor — a supervised elimination diet may be the next step.
In Australia, you can also ask for a referral to a gastroenterologist or a dietitian experienced in coeliac disease. Coeliac Australia (coeliac.org.au) is also an excellent resource.

You Deserve Answers

If you're reading this and recognising yourself in any part of my story — the exhaustion, the fog, the feeling that something is just off — please don't dismiss it.

Getting that diagnosis was one of the hardest and most important moments of my life. It wasn't easy to accept that things had to change permanently. But understanding why my body was struggling gave me back something I hadn't realised I'd lost: the ability to actually take care of myself.

You deserve the same clarity.

If you've been navigating a similar journey, I'd love to hear from you in the comments. And if you haven't already, check out my post on brain fog and celiac disease — it goes deeper into how gluten was silently affecting my mind.

Disclaimer: This post is based on my personal experience and general health information. Always consult a qualified medical professional for diagnosis and treatment.