Celiac disease is an autoimmune disease. When someone with celiac disease eats gluten, a protein found in wheat, barley, and rye, their immune system launches an attack on the lining of the small intestine. This self-directed damage is the hallmark of autoimmune conditions, and celiac disease is one of the best-understood examples. It affects roughly 1% of the population in the United States, with even higher rates in some European countries (nearly 2% in Finland).
What Makes Celiac Disease Autoimmune
In a typical food intolerance, your body struggles to digest something but doesn’t attack its own tissues. Celiac disease works differently. Gluten fragments cross into the intestinal wall, where an enzyme called tissue transglutaminase modifies them. In people who carry specific immune system genes (called HLA-DQ2 or HLA-DQ8), those modified gluten fragments trigger two distinct immune responses.
The first is an innate response in the surface layer of the intestine, where immune cells infiltrate and damage the tissue directly. The second is an adaptive response in the deeper tissue beneath that lining, where the immune system generates inflammatory signals that destroy the tiny, finger-like projections (villi) responsible for absorbing nutrients. This destruction, called villous atrophy, is the defining feature of celiac disease and the reason it causes such widespread health problems. Your body is essentially dismantling its own digestive machinery every time you eat gluten.
Genetics and Who Gets It
More than 90% of people with celiac disease carry the HLA-DQ2 gene, and most of the remainder carry HLA-DQ8. These genes are necessary for the disease to develop, but they aren’t sufficient on their own. Between 30% and 40% of the general population carries one of these genes, yet only about 3% of carriers ever develop celiac disease. Other genetic and environmental factors play a role in determining who actually gets sick and who doesn’t.
This genetic link is useful in diagnosis. If you test negative for both HLA-DQ2 and HLA-DQ8, celiac disease is effectively ruled out. That test is especially helpful for people already eating gluten-free, since standard blood tests and biopsies become unreliable once gluten has been removed from the diet.
Symptoms Beyond the Gut
Many people picture celiac disease as a digestive condition: diarrhea, bloating, weight loss. Those symptoms are common, but more than half of adults with celiac disease present with problems that have nothing to do with digestion. This is part of what makes it an autoimmune disease rather than a simple gut problem. The immune activation and nutrient malabsorption ripple outward across the body.
Anemia is the second most common way celiac disease shows up in adults, appearing in roughly 20% of patients at diagnosis. About 50% of patients have reduced bone density, which can progress to osteoporosis. A skin condition called dermatitis herpetiformis causes intensely itchy blisters on the elbows, knees, buttocks, and scalp. It’s driven by the same autoimmune process and can appear even without digestive symptoms.
Neurological effects are surprisingly frequent. Coordination problems originating in the cerebellum account for about half of the neurological presentations. Nearly 39% of celiac patients in one study met criteria for peripheral neuropathy, which causes tingling, numbness, or pain in the hands and feet. Children may show delayed growth, short stature, or late onset of puberty as their only signs of the disease. Up to 8.3% of children evaluated for short stature turn out to have celiac disease.
How Celiac Disease Is Diagnosed
The first step is a blood test measuring antibodies against tissue transglutaminase (called tTG-IgA). This test has high specificity, meaning a positive result is very likely to be correct. Your doctor should also check your total IgA levels, because some people have an IgA deficiency that makes the standard test unreliable. If that deficiency is present, alternative antibody tests are used instead.
A positive blood test is typically followed by an upper endoscopy with biopsies of the small intestine. Because the damage from celiac disease can be patchy rather than uniform, at least four biopsy samples from different sites are recommended. One important caveat: if you’ve already gone gluten-free before testing, both the blood work and biopsy can come back falsely normal. You need to be eating gluten for the tests to work, which is why doctors sometimes recommend a “gluten challenge” period before testing.
Treatment and Intestinal Healing
The only established treatment for celiac disease is a strict, lifelong gluten-free diet. There is no medication that stops the autoimmune response. Once gluten is removed, the intestine begins repairing itself within days. Most people experience significant healing within a few months, though complete recovery can take up to two years in some cases. Symptoms like bloating and diarrhea often improve faster than the intestinal lining itself heals.
Strictness matters. Even small amounts of gluten can reignite the immune response and restart the cycle of damage. A small percentage of patients, estimated at 1% to 4% of those with celiac disease, develop what’s called refractory celiac disease, where symptoms and intestinal damage persist despite 12 or more months on a strict gluten-free diet. This is divided into two types based on the characteristics of the immune cells involved, with the second type carrying more serious health risks.
What Happens if It Goes Untreated
Because celiac disease is autoimmune and progressive, leaving it untreated leads to cumulative damage. Ongoing intestinal destruction reduces nutrient absorption, which over time can cause severe bone loss, chronic anemia, and nerve damage. Infertility is another recognized complication, and some advanced effects like significant bone loss may not be fully reversible even after starting a gluten-free diet. Liver inflammation is also associated with active celiac disease, and up to 10% of people with unexplained elevations in liver enzymes have been found to have undiagnosed celiac disease.
Links to Other Autoimmune Conditions
Celiac disease clusters with other autoimmune disorders at rates well above the general population. Type 1 diabetes is one of the most common associations. The two conditions share genetic risk factors, and children diagnosed with type 1 diabetes are routinely screened for celiac disease. Autoimmune thyroid conditions, including Hashimoto’s thyroiditis and Graves’ disease, also co-occur frequently.
Less common associations include Addison’s disease (affecting the adrenal glands), autoimmune hepatitis, vitiligo, and alopecia. The pattern suggests that celiac disease may predispose the immune system to broader autoimmune activity, with gluten potentially serving as an ongoing trigger that keeps the immune system in a heightened state. Maintaining a strict gluten-free diet may reduce the risk of developing additional autoimmune conditions, though this remains an area of active investigation.