The Coeliac Alphabet

Villous atrophy is damage to the tiny finger-like projections (villi) lining the small intestine. In coeliac disease, gluten triggers the immune system to flatten these villi, reducing nutrient absorption. It's graded by the Marsh classification (0–3c).

A small-bowel biopsy — multiple tissue samples from the duodenum taken via endoscopy — is the gold standard for diagnosing coeliac disease. Samples are graded using the Marsh-Oberhuber scale to assess villous damage.

Accidental transfer of gluten to a gluten-free food, often through shared utensils, surfaces, or cooking oil. Not to be confused with 'cross-contamination' (a food-safety term). Even trace amounts can cause immune damage in coeliacs.

A skin manifestation of coeliac disease — intensely itchy blisters, usually on elbows, knees, and buttocks. Caused by IgA antibody deposits under the skin. Treated with a strict GF diet and sometimes Dapsone.

Endomysial antibodies (EMA-IgA) — a highly specific blood test for coeliac disease. A positive EMA is nearly always coeliac, but it's less sensitive than tTG-IgA so both are often used together.

Fermentable carbohydrates (Fermentable Oligo-, Di-, Mono-saccharides And Polyols). Some coeliacs with persistent symptoms benefit from a low-FODMAP diet, which reduces gut fermentation. Wheat is both gluten-containing and high-FODMAP — two separate reasons to avoid it.

The alcohol-soluble fraction of gluten protein in wheat. Gliadin peptides (especially 33-mer gliadin) trigger the autoimmune cascade in coeliac disease. Anti-gliadin antibody tests are now superseded by more specific tTG and EMA tests.

Genetic markers found in >99% of coeliacs. HLA-DQ2 (present in ~90%) or HLA-DQ8 (~8%) are necessary but not sufficient for coeliac disease — about 30% of the population carries these genes but only ~1% develops coeliac. A negative result rules out coeliac disease.

Selective IgA deficiency affects ~2–3% of coeliacs (10× more common than in the general population). As tTG-IgA, EMA, and DGP tests all use IgA antibodies, standard coeliac blood tests will be falsely negative. IgG-based tests are used instead.

The middle section of the small intestine (between the duodenum and ileum), where most nutrient absorption occurs. In coeliac disease, villous atrophy begins in the proximal duodenum and, if severe, extends into the jejunum.

An ancient wheat variety (also called Khorasan wheat) that contains gluten and is NOT safe for coeliacs, despite marketing claims. The same applies to all ancient wheat varieties — spelt, einkorn, emmer — all contain gluten.

Secondary lactose intolerance is common in newly-diagnosed coeliacs because the lactase enzyme is produced in the villi tips — which are damaged. It usually resolves as the gut heals on a GF diet. A temporary dairy-free period is sometimes recommended.

A histological grading system for intestinal damage in coeliac disease, from Marsh 0 (normal) to Marsh 3c (complete villous atrophy). Most coeliacs present at Marsh 3a–3c. Also used to monitor recovery on a GF diet.

When symptoms and/or villous atrophy persist after 12 months of a strict GF diet. The most common cause is inadvertent gluten ingestion (often hidden sources). Less commonly: refractory coeliac, SIBO, microscopic colitis, or other diagnoses.

Pure oats are naturally gluten-free but are frequently contaminated with wheat. Only certified gluten-free oats should be consumed. About 5% of coeliacs react to avenin (the oat protein) — introduce GF oats slowly and monitor for symptoms.

Parts per million — the unit used to measure gluten in food. The Codex Alimentarius and EU regulation set the GF threshold at <20 ppm. The 'very low gluten' threshold is <100 ppm. Most certified GF products contain <5 ppm.

A naturally gluten-free seed (not a grain, botanically) that's safe for coeliacs. Rich in protein and all essential amino acids. Some batches are contaminated with wheat — choose certified GF quinoa. Not related to coeliac trigger proteins.

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