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What Celiac Disease Is and How It Works in Your Body

Celiac disease is an autoimmune condition where eating gluten—a protein found in wheat, barley, and rye—triggers your immune system to attack your small intestine. Unlike a food allergy or intolerance, celiac disease causes your body's defense system to mistakenly view gluten as a threat. When this happens, your immune system produces antibodies that damage the lining of your small intestine, which is responsible for absorbing nutrients from food.

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The damage to your intestines means your body cannot properly absorb vitamins, minerals, and other nutrients from the food you eat. This malabsorption can lead to various health problems over time, including anemia, weak bones, and nutritional deficiencies. The condition affects about 1 in 100 people worldwide, though many cases go undiagnosed for years because symptoms vary widely from person to person.

What makes celiac disease different from other digestive conditions is that it has a clear trigger: gluten. Once you understand this connection, you can make informed decisions about your diet and health. Even small amounts of gluten—as little as 20 parts per million—can damage the intestines of someone with celiac disease, which is why managing the condition requires careful attention to food choices.

The disease can develop at any age, even in people who have eaten gluten their entire lives without problems. Some people develop celiac disease after an infection, surgery, pregnancy, or period of emotional stress. Others may have genetic predisposition and never develop symptoms. Understanding these basics helps explain why diagnosis can be tricky and why getting proper medical evaluation matters.

Practical Takeaway: Celiac disease is an autoimmune condition, not a preference or mild sensitivity. Learning how gluten damages the intestines of people with celiac disease explains why dietary changes are medically necessary, not optional.

Common Celiac Disease Symptoms You Should Know About

Celiac disease symptoms vary dramatically from person to person, which is one reason diagnosis is often delayed. Some people experience severe digestive problems, while others have no digestive symptoms at all. The symptoms can also change over time or come and go unpredictably. Common digestive symptoms include chronic diarrhea or constipation, bloating, gas, abdominal pain, and nausea after eating gluten-containing foods.

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Beyond the digestive tract, celiac disease can cause symptoms throughout the entire body. Many people report fatigue and weakness, which results from poor nutrient absorption. Brain fog or difficulty concentrating is surprisingly common. Some people experience headaches or migraines, particularly after eating gluten. Mood changes, including depression or anxiety, have been linked to celiac disease in multiple research studies. These non-digestive symptoms sometimes appear years before someone develops obvious stomach problems.

Skin manifestations can also occur. Dermatitis herpetiformis is a skin condition associated with celiac disease that causes intense itching, burning, and blistering. Not everyone with celiac disease develops this condition, but it's one of the clearest physical indicators. Joint pain and muscle aches are frequently reported, sometimes misdiagnosed as arthritis or fibromyalgia. Mouth sores, hair loss, and brittle nails can indicate nutritional deficiencies related to celiac disease.

Children with celiac disease may show different symptoms than adults. Kids might be shorter than average, fail to gain weight properly, or show delayed development. They may experience vomiting, chronic diarrhea, or a swollen belly. Some children become irritable or withdrawn. Delayed puberty can sometimes be connected to undiagnosed celiac disease. Because symptoms in children can be subtle or attributed to other causes, pediatric celiac disease often remains undiagnosed for years.

It's important to note that roughly 40% of people with celiac disease have no obvious symptoms at all—a condition called silent celiac disease. These individuals still experience intestinal damage but may not notice anything wrong until complications develop or testing reveals the condition. This is why symptoms alone are not reliable for diagnosis.

Practical Takeaway: Celiac disease symptoms are widespread and can affect digestion, energy levels, mood, skin, and joints. If you notice multiple symptoms—even ones that seem unrelated—keeping a record of when they occur and what you ate can help your doctor identify patterns.

How Celiac Disease Is Diagnosed: Tests and Medical Evaluation

If celiac disease is suspected, diagnosis requires specific blood tests and sometimes a small intestinal biopsy. The most common initial test measures tissue transglutaminase (tTG) antibodies, which people with celiac disease produce when exposed to gluten. Another test looks for endomysial antibodies (EMA). These antibody tests are quite accurate but only work if the person has been eating gluten recently—at least for several weeks before testing.

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Your doctor may also check for total immunoglobulin A (IgA) levels, since some people have IgA deficiency, which can affect test accuracy. Some medical centers now offer genetic testing to look for HLA-DQ2 and HLA-DQ8 genes, which are present in 99% of celiac disease cases. If you have these genes, you may or may not develop celiac disease, but their absence essentially rules out the condition.

If blood tests suggest celiac disease, the next step is usually an upper endoscopy, which allows a doctor to see your small intestine and take tiny tissue samples for examination under a microscope. The biopsy can show whether gluten has damaged the intestinal lining and to what extent. This procedure requires sedation and takes about 30 minutes. It's considered the gold standard for diagnosis because it shows actual physical damage to the intestines.

One critical point: you must continue eating gluten-containing foods for at least 4-6 weeks before blood tests and during any endoscopy procedure. Otherwise, your intestines may have already started healing, and tests could come back negative even if you have celiac disease. This requirement often surprises people who have already noticed that gluten makes them feel worse. It's important to discuss this timing with your healthcare provider before making any dietary changes.

After diagnosis is confirmed, follow-up testing may occur at intervals to ensure intestinal healing and monitor nutrient absorption. Some doctors recommend repeat endoscopy after 1-2 years to confirm that avoiding gluten has allowed the intestinal lining to heal. Blood tests can also track whether antibody levels decrease over time, indicating successful dietary management.

Practical Takeaway: Getting an accurate celiac diagnosis requires continuing to eat gluten while undergoing testing. Planning these medical evaluations carefully with your doctor ensures you get reliable results rather than false negatives.

Understanding the Difference Between Celiac Disease, Non-Celiac Gluten Sensitivity, and Wheat Allergy

Many people confuse celiac disease with other gluten-related conditions, but they are distinct medical issues requiring different management approaches. Non-celiac gluten sensitivity (NCGS) affects an estimated 6% of the population. People with NCGS experience symptoms similar to celiac disease—bloating, fatigue, headaches, brain fog—but their blood tests for celiac disease are negative and their intestines show no damage. The exact mechanism causing NCGS remains unclear, but it is a real condition that improves when gluten is eliminated from the diet.

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A wheat allergy is another condition often confused with celiac disease. This is a true allergic reaction where the immune system produces immunoglobulin E (IgE) antibodies against wheat proteins. Symptoms can include itching in the mouth, swelling of lips or throat, hives, and in severe cases, anaphylaxis. A wheat allergy can be diagnosed through skin prick tests or specific IgE blood tests. Importantly, people with wheat allergies can usually eat barley and rye without problems, whereas people with celiac disease cannot tolerate any of the three gluten-containing grains.

The significance of distinguishing between these conditions goes beyond labeling. Someone with celiac disease must avoid gluten for life because any exposure damages their intestines, even without symptoms. Someone with NCGS might have more flexibility, as research is still evolving on long-term effects. Someone with a wheat allergy must avoid wheat but can eat other gluten sources. The diagnostic path also differs: celiac disease diagnosis involves blood tests and possible intestinal biopsy, while wheat allergy diagnosis uses all