A Protein Found in Wheat Some Can’t Digest A Closer Look

The protein in wheat that some people cannot digest is gluten — specifically a component called gliadin. For individuals with celiac disease or non-celiac gluten sensitivity, eating gluten triggers an abnormal immune response or digestive discomfort. Unlike a simple food allergy, this reaction can damage the small intestine over time if left untreated.

What is the protein in wheat that some people cannot digest?

The key protein is gluten, which is actually a family of proteins found in wheat, barley, and rye. The part that causes trouble for many people is gliadin, a fraction of gluten. In people with celiac disease, the immune system treats gliadin as a threat. This leads to inflammation and damage to the lining of the small intestine. Not everyone reacts the same way. Some people experience symptoms without the intestinal damage seen in celiac disease — this is called non-celiac gluten sensitivity.

What happens in the body when someone with celiac disease eats gluten?

When a person with celiac disease eats gluten, their immune system attacks the gliadin protein as if it were harmful. This immune response also damages the tiny finger-like projections called villi in the small intestine. Villi are responsible for absorbing nutrients from food. Over time, repeated damage flattens the villi, leading to malnutrition, weight loss, and other health problems. This process is not an allergy or an intolerance in the usual sense — it is an autoimmune reaction.

What is non-celiac gluten sensitivity?

Non-celiac gluten sensitivity (NCGS) is a condition where people have symptoms similar to celiac disease — such as bloating, diarrhea, abdominal pain, and fatigue — but they do not test positive for celiac disease or wheat allergy. The mechanism is not fully understood. Some studies suggest that other components in wheat, like fructans (a type of carbohydrate), may be responsible for symptoms rather than gluten itself. There is no specific test for NCGS. Diagnosis is made when symptoms improve on a gluten-free diet and return when gluten is reintroduced, while ruling out celiac disease.

How is celiac disease diagnosed?

Diagnosis begins with a blood test that looks for certain antibodies, most commonly tissue transglutaminase antibodies (tTG-IgA). If the blood test is positive, doctors usually recommend an upper endoscopy with biopsy of the small intestine to confirm damage to the villi. It is important not to start a gluten-free diet before testing — removing gluten can make test results falsely negative. A reliable diagnosis requires that gluten is still in the diet during testing.

What are the symptoms of gluten intolerance?

Symptoms vary widely. In celiac disease, common digestive symptoms include bloating, chronic diarrhea, gas, abdominal pain, and nausea. Some people experience non-digestive symptoms such as fatigue, joint pain, skin rash (dermatitis herpetiformis), anemia, or tingling in the hands and feet. Non-celiac gluten sensitivity typically causes similar digestive discomfort but lacks the autoimmune markers and intestinal damage. Because symptoms overlap with other conditions like irritable bowel syndrome, diagnosis can be challenging.

What treatments are available for people who cannot digest this protein?

The only proven treatment for celiac disease is a strict, lifelong gluten-free diet. This means avoiding all foods made from wheat, barley, and rye. Oats are often contaminated with gluten, so certified gluten-free oats are recommended. Many processed foods contain hidden gluten, so reading labels is essential. For non-celiac gluten sensitivity, the same diet is used, but some people may tolerate small amounts of gluten. No medication currently replaces the gluten-free diet. Some clinical trials are exploring enzyme supplements that break down gluten, but none have been proven effective for treating celiac disease.

Can gluten sensitivity develop later in life?

Yes. Celiac disease can appear at any age, even in people who previously tolerated gluten without problems. It is triggered by a combination of genetic predisposition and an environmental factor — sometimes an infection, pregnancy, surgery, or severe stress. Non-celiac gluten sensitivity can also begin later in life, though the triggers are less clear. If you develop new digestive symptoms after eating wheat, it is worth discussing with a doctor rather than self-diagnosing.