Villous Atrophy

Villous atrophy is the defining feature of coeliac disease. It’s what separates a positive coeliac diagnosis from a suspicion, and it’s the physical mechanism that explains why coeliac disease causes so much more than just stomach problems.

What Is Villous Atrophy?

The small intestine is lined with millions of tiny finger-like projections called villi. Their job is to maximise the surface area available for absorbing nutrients. Healthy villi are tall and closely packed — under a microscope, they look like a dense carpet. They’re responsible for absorbing iron, calcium, vitamin D, B vitamins, fats, proteins, and most of what your body needs from food.

In coeliac disease, the immune system’s response to gluten triggers chronic inflammation in the intestinal lining. Over time, this inflammation destroys the villi. They shorten, then flatten, then in severe cases disappear almost entirely. The carpet becomes smooth floor. This is villous atrophy.

The consequence is malabsorption — sometimes dramatic, sometimes subtle, always significant. The small intestine is structurally intact but its functional capacity is severely reduced.

The Marsh classification is the system used to grade the degree of damage seen on biopsy:

• Marsh 1: Increased intraepithelial lymphocytes (immune cells in the gut lining). Villi look normal.
• Marsh 2: Lymphocyte increase plus crypt hyperplasia (enlarged crypts between villi).
• Marsh 3a: Mild villous atrophy — villi are shorter than normal.
• Marsh 3b: Marked villous atrophy — villi are significantly flattened.
• Marsh 3c: Total villous atrophy — villi are essentially absent. The lining appears flat.

Most newly diagnosed adults with symptomatic coeliac disease fall in the Marsh 3 range. The degree of atrophy doesn’t always correlate directly with symptom severity — someone with Marsh 3c can have surprisingly mild digestive symptoms, while someone with Marsh 1–2 changes may feel very unwell.

On a strict gluten-free diet, villous atrophy reverses. Villi regenerate as inflammation subsides. This healing is gradual — typically 12–24 months in adults — and is confirmed by a follow-up biopsy. Some adults take longer to heal completely, and persistent partial atrophy despite a strict diet warrants further investigation.

What This Means for You

Your Marsh score tells you the state of your gut at diagnosis. It’s not a permanent label — it’s a starting point. The goal of the gluten-free diet is to bring that score back down to Marsh 0 through gut healing.

Related in the Coeliac Alphabet: Intestinal Villi · Enteropathy · Biopsy · back to the full A–Z.