Celiac Disease and Gluten Sensitivity

Celiac disease is a chronic immune-mediated enteropathy of the small intestine triggered in genetically susceptible people by dietary gluten, the storage protein of wheat, barley, and rye. The immune response damages the small-bowel mucosa, blunting the villi and impairing absorption, so the disorder is at once an immunological condition and a leading cause of nutrient malabsorption. The term gluten sensitivity is also used for a separate, non-autoimmune reaction to gluten-containing foods.

Definition

Celiac disease is a chronic, immune-mediated enteropathy of the small intestine precipitated by exposure to dietary gluten in genetically predisposed individuals, characterised by villous atrophy, crypt hyperplasia, and malabsorption that respond to gluten withdrawal.

Scope

This topic covers celiac disease as a clinical entity within gastrointestinal and liver nutrition, the related concept of non-celiac gluten sensitivity, and the nutritional consequences of small-bowel mucosal damage. It frames the immunology, the malabsorption that follows villous atrophy, the basis of diagnosis, and the central role of gluten exclusion as reference knowledge; it does not provide individualised dietary prescriptions.

Core questions

• How does dietary gluten trigger immune-mediated injury of the small-intestinal mucosa?
• Why does villous atrophy in celiac disease cause malabsorption and nutrient deficiency?
• How are celiac disease and non-celiac gluten sensitivity distinguished?
• What is the nutritional basis and rationale of gluten exclusion?

Key concepts

• Gluten and gliadin
• Villous atrophy and crypt hyperplasia
• HLA-DQ2/DQ8 genetic susceptibility
• Tissue transglutaminase antibodies
• Malabsorption
• Gluten-free diet
• Non-celiac gluten sensitivity
• Micronutrient deficiency (iron, folate, calcium, vitamin D)

Mechanisms

In genetically susceptible people who carry the HLA-DQ2 or HLA-DQ8 haplotypes, deamidated gliadin peptides are presented to CD4 T cells, driving an adaptive immune response that injures the small-intestinal epithelium. The resulting villous atrophy and crypt hyperplasia reduce the absorptive surface and brush-border enzyme activity, producing malabsorption of iron, folate, calcium, fat-soluble vitamins, and other nutrients. Serological markers such as anti-tissue-transglutaminase antibodies reflect the immune process and support diagnosis, which is confirmed against duodenal histology; removal of dietary gluten allows the mucosa to heal and absorption to recover (Rubio-Tapia 2023; Ludvigsson 2014). Non-celiac gluten sensitivity describes symptomatic reactions to gluten-containing food in the absence of the autoimmune and histological features of celiac disease, diagnosed by exclusion and challenge (Catassi 2015).

Clinical relevance

Celiac disease is a common cause of malabsorption and of deficiencies such as iron-deficiency anaemia and low bone mineral density, and it can present with intestinal or extraintestinal features. Understanding its mechanism explains why it is both an immunological diagnosis and a nutritional one, and why a strict gluten-free diet is the basis of management. This entry is reference material describing the condition and its nutritional consequences; it is not a substitute for individualised diagnosis or dietary care.

Epidemiology

Celiac disease affects roughly one percent of populations in many regions, though a large proportion of cases remain undiagnosed, and it is more frequent in first-degree relatives and in people with certain autoimmune conditions. The supporting guidelines summarise its prevalence and the case for serological case-finding (Rubio-Tapia 2023; Ludvigsson 2014).

History

Although a wasting disorder relieved by dietary change was described in antiquity and refined in nineteenth-century clinical accounts, the causal role of wheat gluten was identified by Willem Dicke in the mid-twentieth century, after which small-bowel biopsy established the characteristic mucosal lesion. Later work defined the HLA association and the serological markers, and contemporary guidelines codified diagnosis and the central role of gluten exclusion (Ludvigsson 2014; Rubio-Tapia 2023). The Salerno criteria subsequently provided a framework for the separate concept of non-celiac gluten sensitivity (Catassi 2015).

Debates

How should non-celiac gluten sensitivity be defined and diagnosed?

Because it lacks the autoimmune serology and histological lesion of celiac disease, non-celiac gluten sensitivity rests on symptom response to gluten withdrawal and challenge, and the boundaries of the entity and the role of other wheat components remain debated.

Seminal works

• rubio-tapia-2023
• ludvigsson-2014
• catassi-2015

Frequently asked questions

Is celiac disease an allergy to gluten?

No. Celiac disease is a chronic immune-mediated enteropathy in genetically susceptible people, distinct from an allergy; the immune response damages the small-intestinal lining and causes malabsorption, and it differs from both wheat allergy and non-celiac gluten sensitivity.

Why does celiac disease cause nutritional deficiencies?

The immune-mediated injury flattens the small-intestinal villi and reduces the absorptive surface, so nutrients such as iron, folate, calcium, and fat-soluble vitamins are absorbed poorly, which can lead to anaemia and low bone density.