Gluten: Coeliac Disease, Real Sensitivity or Modern Myth? What the Science Actually Says

Gluten: the most accused ingredient on our plates

In recent years, gluten has become the number one enemy of digestive health. Free-from aisles are expanding rapidly, restaurants are advertising adapted menus, and friends are giving up bread "to feel better"… The topic is everywhere. But behind this social phenomenon lie very different medical realities — and distinguishing between them is essential if you want to make the right decisions for your health.

Coeliac disease: a serious autoimmune condition

Coeliac disease is not a simple intolerance. It is a multisystemic autoimmune disease triggered, in genetically predisposed individuals — most of whom carry the HLA-DQ2 or HLA-DQ8 antigens — by the ingestion of gluten, a protein found in wheat, barley, and rye.

Here is what actually happens: the immune system mistakes gliadin (a component of gluten) for a pathogen and produces antibodies that attack the villi lining the small intestine. These small finger-like structures are essential for nutrient absorption. Their progressive destruction — known as villous atrophy — leads to chronic malabsorption: iron, vitamin B12, folate, and calcium can no longer pass properly into the bloodstream, resulting in severe deficiencies, anaemia, and osteoporosis.

Coeliac disease affects approximately 1% of the global population, yet it remains significantly underdiagnosed. Diagnosis relies on serological tests (particularly anti-tissue transglutaminase IgA antibodies) and an intestinal biopsy. One crucial point: these tests are only valid if the person is still consuming gluten at the time of testing. The only effective treatment is a strict, lifelong gluten-free diet.

Non-coeliac gluten sensitivity: real, but still poorly understood

Between clearly diagnosed coeliac disease and those who tolerate gluten without any difficulty, there exists a grey area: non-coeliac gluten sensitivity (NCGS).

This condition is defined by digestive symptoms — bloating, abdominal pain, diarrhoea, constipation, nausea — and extra-digestive symptoms — fatigue, brain fog, headaches, joint pain — that appear following gluten ingestion and resolve on a gluten-free diet, after formally ruling out coeliac disease and wheat allergy.

The underlying mechanisms are still poorly understood. Several avenues are being investigated, including:

• Increased intestinal permeability ("leaky gut"), involving a protein known as zonulin
• Non-specific irritation of the intestinal mucosa
• An innate inflammatory response, occurring without the production of specific antibodies

To date, there is no reliable biomarker to diagnose NCGS: it remains a diagnosis of exclusion. Prevalence estimates vary widely — some sources suggest figures as high as 15% of the population — but these figures remain uncertain precisely because no objective test exists.

Wheat allergy: an important distinction

A third clinical picture deserves a mention: wheat allergy. Unlike NCGS, this is an IgE-mediated immunological reaction to the proteins in wheat (including gluten, but also albumins and globulins). Symptoms are often rapid in onset and may include urticaria, swelling, or, in severe cases, anaphylaxis. It is a fully-fledged allergy and should be managed as such.

What the myths cause us to miss

The rise of gluten-free eating as a lifestyle choice — without any medical diagnosis — creates several real-world problems.

Firstly, starting a gluten-free diet before undergoing coeliac testing distorts the results and can delay a critical diagnosis. Antibody levels and intestinal damage both normalise on a gluten-free diet, making diagnosis impossible.

Secondly, a gluten-free diet is not without consequence. It can lead to nutritional imbalances, reduced fibre intake, and a negative impact on the gut microbiome.

Thirdly, for people who have no gluten-related condition, a varied and plentiful intake of wholegrains is generally beneficial for digestive health.

What to do if gluten makes you feel unwell

Here are the steps recommended by healthcare professionals:

• Do not eliminate gluten before speaking to a doctor
• Request serological tests for coeliac disease (whilst continuing to eat gluten)
• Rule out a wheat allergy if symptoms appear quickly after eating
• If results are negative, explore NCGS with a gastroenterologist or registered dietitian
• Consider a structured and gradual elimination diet, with reintroduction phases to assess your actual tolerance

In summary

	Coeliac disease	NCGS	Wheat allergy
Mechanism	Autoimmune	Poorly understood	IgE-mediated (allergic)
Diagnosis	Serology + biopsy	Diagnosis of exclusion	Allergy testing
Treatment	Strict lifelong GFD	Adaptable GFD	Wheat avoidance
Prevalence	~1%	Up to ~15%	Variable

Gluten is neither harmless for everyone, nor dangerous for the majority. The key, as ever in gut health, lies in individualised diagnosis rather than following collective trends. Your gut deserves better than a decision made by default.