What Is Celiac Disease, Exactly? Experts Break Down the Autoimmune Condition

This informational guide, part of PS's Condition Center, lays out the realities of this health concern: what it is, what it can look like, and strategies that medical experts say are proven to help. You should always consult your doctor regarding matters pertaining to your health and before starting any course of medical treatment.

You might be familiar with celiac disease if you have a gluten-free friend or family member living with the condition. Or maybe you've heard it mentioned on social media, as users post about their experiences navigating the celiac lifestyle. Well, it turns out the condition isn't very common, but it can have a very significant impact on your life, especially your diet.

About one in 133 Americans has celiac disease, an autoimmune condition that requires strict adherence to a gluten-free diet, according to Beyond Celiac, a patient advocacy and research-driven celiac disease organization. The organization also estimates that up to 83 percent of Americans who have celiac disease go undiagnosed or are misdiagnosed with something else — and it usually takes a whopping six to 10 years to get a proper diagnosis.

This is partly because symptoms can be very vague — but there's also still just a general lack of awareness about the condition. That's alarming because when left untreated, celiac disease can contribute to long-term health consequences like osteoporosis, infertility, and even cancer.

So, what is celiac disease, exactly — and how can you tell if you're at risk for it? Ahead, a gastroenterologist and dietitian break down the symptoms and causes of celiac disease, as well as what the diagnosis process and treatment look like.

Aditi M. Stanton, MD, is a board-certified gastroenterologist at Gastro Health, a medical group that specializes in treating gastrointestinal disorders and digestive health.

Taylor Silfverduk, RDN, is a dietitian who specializes in treating clients with celiac disease.

Celiac disease is an autoimmune condition that affects the duodenum (the first part of the small intestine), which is located between the stomach and the middle part of the small intestine, explains Aditi M. Stanton, MD, a board-certified gastroenterologist at Gastro Health, a medical group that specializes in treating gastrointestinal disorders and digestive health.

When someone with celiac disease eats gluten — a protein found in wheat, barley, and rye — this triggers their body to launch an immune response that attacks the small intestine, according to the Celiac Disease Foundation. This leads to damage of the villi, itty-bitty hair-like projections lining the inside of the small intestine.

When this damage occurs, it can lead to gastrointestinal symptoms and nutritional deficiencies, per MedlinePlus. It can also contribute to other long-term health complications, such as other autoimmune diseases (including type 1 diabetes) and infertility. Although rare, it could increase your risk of certain cancers, including non-Hodgkin's lymphoma, as well.

"The symptoms of celiac disease can be pretty broad," says Dr. Stanton. Per Beyond Celiac, there are over 250 known symptoms, but Dr. Stanton says she typically sees digestive issues in celiac patients. These include:

Some of the more surprising non-GI symptoms, per the Mayo Clinic, include:

Celiac disease often causes iron-deficiency anemia, adds Dr. Stanton, which can lead to symptoms like tiredness and headaches. Celiac disease can also damage the part of the small intestine where iron, folate, and vitamin B12 are absorbed, and a lack of these nutrients can lead to anemia.

Bone density loss is possible in people with celiac disease, too, says Tayler Silfverduk, RDN, a dietitian who specializes in treating clients with celiac disease. "Most of my clients have bone density mineral issues, and that's because a lot of the nutrients for your bones, such as calcium, are absorbed in the duodenum of the small intestine," she explains.

According to a 2016 study that looked at newly diagnosed celiacs, 56.1 percent had osteopenia (lower-than-normal bone density) and 29.2 percent had osteoporosis (a disease that weakens your bones so they're more likely to fracture or break).

In some cases, celiac disease can actually be asymptomatic, says Silfverduk. While those with "silent celiac disease" don't experience symptoms, eating gluten still damages the small intestine and could lead to long-term health issues.

Celiac disease is a genetic autoimmune disorder and can only occur in people who have certain genes, says Stanton. Experts don't yet fully understand all of the environmental factors that may play a role in celiac disease, she adds.

Here's a look at the risk factors:

"Celiac disease is diagnosed through a combination of bloodwork and small bowel biopsy," says Stanton. If a doctor suspects you have celiac disease, they'll usually start with the blood test first.

The Tissue Transglutaminase IgA (tTG-IgA) test checks for antibodies in the blood that indicate celiac disease. Elevated levels mean your body is having an immune response to gluten. If your bloodwork comes back positive for antibodies, then the next step would be to have an endoscopy, says Stanton.

During this procedure, which happens under sedation, your doctor will insert a small flexible tube with a camera and light on the end through your mouth to take a biopsy of the duodenum, per NYU Langone. A pathologist will then check the collected samples for damage to the small intestine. If you have celiac disease, the villi in your small intestine will appear flattened rather than raised, according to Columbia University Irving Medical Center.

You must be eating gluten at the time of the endoscopy, says Stanton. Once you stop eating gluten, your body will start to heal and your doctor won't be able to see the full extent of the damage to your small intestine. "We really need to see that inflammatory response in the biopsy in order to diagnose celiac disease," she says.

After you've been diagnosed with celiac disease, Stanton generally recommends visiting your gastroenterologist three to six months later to have your antibodies rechecked to make sure your levels are coming down. Your doctor may suggest repeating your labs every three to six months until your antibody levels are considered normal, she says.

You'll also want to monitor your vitamins and minerals about once a year, on average, adds Stanton, because celiac disease increases your risk for certain nutritional deficiencies. She usually keeps an eye on vitamin D, vitamin B12, and iron in her celiac patients.

"I also talk to patients about a bone density scan at some point because there is an association between bone loss and celiac disease as well," Stanton says. Some medical centers even recommend a follow-up endoscopy and biopsy a few years after your diagnosis to ensure your intestines have healed.

The only treatment for celiac disease is eliminating gluten from your diet, says Stanton. This means avoiding all foods and drinks that contain wheat, barley, and rye — as well as doing your best to minimize your chances of cross-contact, which is when a gluten-free food comes into contact with a gluten-containing ingredient or food, says Silfverduk.

Stanton recommends celiac patients work with a dietitian early on in their diagnosis to learn the ins and outs of gluten-free living. For starters, you'll need to become a diligent label reader at the grocery store because it's not always obvious when packaged foods, like sauces and marinades, have gluten in them.

Reducing your cross-contact risk at home and at restaurants is also key because even a crumb of gluten can make someone with celiac disease sick. An example of cross-contact at a restaurant is when potatoes (which are naturally gluten-free) are fried in the same oil as breaded onion rings. A dietitian can help you figure out what questions to ask when dining out (or at someone else's home) to stay safe.

The bottom line: Adhering to a strict gluten-free lifestyle can be challenging, especially at first. So Silfverduk tells celiacs not to compare themselves to others living with this condition and not to be too hard on themselves if they accidentally eat gluten. "Remind yourself that you're doing your best and you know what's best for you," she says.

Christina Heiser is a New York City-based freelance writer who's been covering health, beauty, fitness, and nutrition for over a decade. Her work has appeared in PS, Women's Health, Shape, Parade, and more.