Celiac disease is an autoimmune disorder where the ingestion of the protein gluten — found in wheat, barley, and rye — leads to damage in the small intestine, making it hard for your body to absorb nutrients in food. (3) And celiac disease is not just a hypersensitivity or allergy to gluten-containing food but an autoimmune disease that causes inflammation of the bowel, says Abdullah Shatnawei, MD, a gastroenterologist at the Cleveland Clinic. So what causes celiac disease, and how do you know if you’re at risk?
What Scientists Believe May Cause Celiac Disease
While scientists don’t yet know the exact causes of celiac disease, they know that genetics play a role. (4) And today, doctors are more aware about celiac disease, Dr. Shatnawei says, and probably have a better understanding about its pathophysiology, meaning how the disease manifests. In people with celiac disease, the immune system forms antibodies to gluten, and those antibodies attack the lining of the small intestine, leading to inflammation and damage to the villi. (5) The villi are finger-like structures lining the small intestine, whose job it is to absorb nutrients from food. (5) Those nutrients are then released into the bloodstream and carried to tissues and other parts of the body. (6) When the villi are damaged, as is the case for people with celiac disease, the body is not able to absorb nutrients properly, leading to malnutrition and absorption deficiencies. Those deficiencies can manifest in different ways: Sometimes, patients will have trouble absorbing many different nutrients, including carbohydrates, fats, minerals, and vitamins, while other times, they will only have trouble with a few, including calcium or iron. (6) Celiac disease is likely the result of a combination of genetic and environmental factors. (5) “We know that celiac is a reaction to gluten in people with a genetic predisposition,” Shatnawei says. “It’s probably this susceptibility and abnormal reaction to gluten that causes bowel inflammation,” though he notes that we don’t yet know why celiac disease happens in a certain group of people. Benjamin Lebwohl, MD, director of clinical research at the Celiac Disease Center at Columbia University in New York City and president of the Society for the Study of Celiac Disease, agrees. “Why people go from not having celiac disease to having celiac disease is a medical mystery,” he says. “Ultimately, we know very little about why some people develop celiac disease and others do not.” Dr. Lebwohl notes that today’s most recent generation seems to have a higher risk of developing celiac disease than previous generations. The higher prevalence may be related to environmental changes, because genes do not change enough in one generation to cause a rise in celiac disease, he explains. And the change is not just about increased awareness of celiac disease: Lebwohl says blood samples stored from the 1950s and tested for celiac markers actually show there was much less evidence of celiac disease in the 1950s than today. One study suggests that the prevalence of undiagnosed celiac disease has increased dramatically in the United States over the past 50 years, increasing fourfold within that time span (from about 0.2 percent to 0.8 percent of the population). The authors of that study noted that while we don’t know the cause, it could be due to something environmental, like a change in the quality, quantity, or processing of cereal, or to changes in early childhood infections. (7) So how do doctors test for celiac disease? In blood tests, they are often testing for the presence of antibodies that indicate the autoimmune response that is characteristic of celiac disease. (6)
Celiac disease is rare and only affects children. In fact, Lebwohl says, celiac disease affects children and adults equally. An estimated 83 percent of Americans who have celiac are undiagnosed or misdiagnosed with other conditions. (8) Many people with celiac disease, regardless of age, remain undiagnosed.If you test negative for celiac disease, you will never have celiac disease in the future. You could actually develop celiac disease at any point, Lebwohl says. One review suggests it may take an individual up to 10 years to be diagnosed. (9) (The exception is if you test negative for one of the related celiac genes, but more on that later.)You can grow out of celiac disease. Once diagnosed, celiac disease is a lifelong condition, Lebwohl says.If you want to know if you have celiac disease, you can try a gluten-free diet and see if your symptoms improve. In fact, you can’t know whether your change in diet and symptoms means you have celiac disease or not, Lebwohl says. The only way to know for sure is to see a doctor and get a blood test, as there are other conditions associated with gluten sensitivity or intolerance, such as nonceliac gluten sensitivity (NCGS) or a wheat allergy. (10)Gluten is bad for everyone. “Apart from celiac disease or individuals who have sensitivity to gluten or wheat, the great majority of individuals tolerate gluten without any apparent ill effect,” Lebwohl says. It also does not appear to carry any long-term risks involving heart or brain health, he says. (11)You can get tested for celiac disease via direct-to-consumer laboratories. Many companies may market celiac and gluten-related blood, stool, and saliva tests, but these are unproven and likely not valid, Lebwohl says. The exception is a blood test that can tell you whether you have one of the celiac genes explained later in this article — but consult a doctor to help you interpret those results.
Having a Family Member With Celiac Disease
Because celiac disease is genetic, if one member of your family has celiac disease, it’s a good bet that you’re at an increased risk of developing it. In fact, if a first-degree relative (parent, child, or sibling) has celiac disease, your risk is about 1 in 22. (12) If a second-degree relative (aunt, uncle, cousin) has it, your risk is about 1 in 39. (12) Other research suggests that if any member of a family has celiac disease, about 1 out of every 10 other family members also has the disease. (4) Some estimates put that number even higher, at about 1 in every 5 to 1 in every 10 other family members. (13)
Having HLA-DQ2 and HLA-DQ8 Genes
“Probably the main risk factor is having [a] celiac gene,” Shatnawei says. Some research suggests that celiac disease only occurs in individuals with certain genes, which are carried by about one-third of the population. (13) That doesn’t mean that one-third of the population has celiac disease — it only means that those people are at risk. If you do not have these genes, you likely don’t have celiac disease. Among people with celiac disease, 95 percent have the HLA-DQ2 gene, and most of the rest of that remaining 5 percent have the HLA-DQ8 gene. (14)
Having Another Autoimmune Condition
Celiac disease is more common in people who have certain other autoimmune diseases, including type 1 diabetes, rheumatoid arthritis, and Addison’s disease. (4) Celiac disease is also an autoimmune disorder.
Having Certain Genetic Disorders
People with genetic disorders like Down syndrome or Turner’s syndrome are often more at risk of developing celiac disease. (4)
Other Possible Risk Factors for Celiac Disease
Some research has suggested certain other factors may increase risk of or be associated with celiac disease. For instance, one study found that incidence of celiac disease in children younger than age 2 was higher in children born in summer and spring compared with winter and autumn, though further study is needed on these observations. (15,16) Another study found evidence that if, in an infant’s first six months of life, parents reported having three or more infections themselves, the infant had an increased risk of developing celiac disease. (17) Regardless, it’s important to know that celiac likely isn’t caused by a single factor but rather a mix of genetic and environmental factors. Indeed, doctors actually used to believe that there was an ideal time to introduce gluten into an infant’s diet, Lebwohl says. But subsequent trials and research found that there was actually no optimal strategy for introducing gluten into a baby’s diet to help prevent celiac disease. “That said, it appears that delaying gluten introduction beyond one year of age could potentially increase the risk of celiac disease, but there is uncertainty even about that,” Lebwohl says. In general, he notes, doctors have very little concrete recommendations at the moment about ways to mitigate the risk of developing celiac disease. “Celiac is more common than people think,” Shatnawei says. “Symptoms are very nonspecific. Awareness by a physician is important to diagnose the disease.” He notes that patients with a family history should definitely get themselves checked out, and ultimately, the best treatment for celiac disease is a gluten-free diet.
