Celiac Disease 101

Understanding the Basics

May is Celiac Awareness Month! Throughout this month, we’ll be diving into celiac disease – what it is, how it’s diagnosed, and how you can live well with it.

Let’s start with the basics.

What Is Celiac Disease?

Celiac disease is a chronic autoimmune disorder. In people with celiac disease, the immune system reacts abnormally to gluten – a protein found in wheat, rye, and barley. When someone with celiac disease eats gluten, their immune system mistakenly attacks the lining of the small intestine.

This attack damages villi, the tiny, finger-like projections that line the inside of the small intestine. These villi play a critical role in absorbing nutrients from the food we eat. When the villi become inflamed or flattened due to ongoing gluten exposure, their ability to absorb important nutrients – like iron, calcium, folate, and fat-soluble vitamins (A, D, E, and K) – is significantly reduced.

Over time, this impaired absorption can lead to malnutrition, even if the person is eating enough food. This is why people with untreated celiac disease may develop conditions like iron-deficiency anemia, low bone density, and delayed growth in children. It’s important to understand that celiac disease is not a food allergy or intolerance – it’s an autoimmune reaction that causes lasting intestinal damage if not managed properly.

Why Does It Happen?

Celiac disease develops due to a combination of genetic, environmental, and immune-related factors.

The strongest known genetic risk factors are two specific genes: HLA-DQ2 and HLA-DQ8. These genes are found in nearly all people with celiac disease. However, carrying one or both of these genes does not mean you will develop the condition – many people have these genes and never get celiac disease.

The key environmental trigger is gluten. In people with celiac disease, gluten interacts abnormally with the immune system. This immune reaction causes inflammation and damage to the small intestine.

Other possible environmental influences, such as infections or significant physical or emotional stress, may also play a role in triggering the disease in genetically susceptible individuals, though the exact mechanisms are still being studied.

Celiac disease can appear at any age – even after years of consuming gluten without any problems. In some people, symptoms may start suddenly after a period of illness, surgery, or life stress. 

What Are the Symptoms?

Celiac disease can affect the body in many ways, not just the digestive system. Some people experience clear gastrointestinal (digestive) symptoms, while others may have issues that seem unrelated, such as fatigue, joint pain, or skin rashes. And some individuals may have no noticeable symptoms at all.

This wide range of possible symptoms makes celiac disease challenging to recognize. It’s often misdiagnosed or mistaken for other health conditions like irritable bowel syndrome (IBS), lactose intolerance, or anemia. In many cases, people live with symptoms for years before receiving a proper diagnosis.

Digestive Symptoms

• Chronic or recurring diarrhea
• Constipation
• Abdominal pain, bloating, or gas
• Nausea or vomiting
• Foul-smelling, or fatty stools (steatorrhea)
• Poor appetite

Non-Digestive Symptoms

• Unintended weight loss
• Fatigue or low energy
• Iron-deficiency anemia (often not responsive to supplements)
• Bone or joint pain
• Osteopenia or osteoporosis
• Headaches or “brain fog”
• Tingling or numbness in hands and feet
• Itchy, blistering skin rash (dermatitis herpetiformis)
• Delayed growth or puberty (children)
• Mood changes (irritability, anxiety, or depression)
• Unexplained infertility
• Dental enamel defects
  

Because symptoms can range from very mild to severe, and because they often overlap with other conditions, celiac disease can be difficult to detect. Some people may not realize they’re affected until they are screened due to family history or related health conditions.

That’s why proper testing is so important. Even if symptoms are vague or absent, gluten can still cause damage to the small intestine in people with celiac disease.

Who Should Get Tested?

Because celiac disease can be difficult to recognize, testing is recommended for people with certain risk factors – even if symptoms are mild or absent.

According to Celiac Canada, you may benefit from screening if you:

• Have a first-degree relative (parent, sibling, or child) with celiac disease
• Have unexplained iron-deficiency anemia
• Experience persistent digestive issues
• Have a skin condition suggestive of dermatitis herpetiformis (an itchy, blistering rash)
• Experience delayed growth, weight loss, or delayed puberty
• Have other autoimmune conditions (e.g., type 1 diabetes or autoimmune thyroid disease)
• Have recurrent miscarriages or unexplained infertility
  

How Is Celiac Disease Diagnosed?

Getting an accurate diagnosis is an essential first step – and it’s important not to stop eating gluten before testing. Removing gluten too early can lead to false-negative results.

If you’re unsure whether testing is right for you, talk to your doctor or a registered dietitian with experience in celiac disease.

Diagnosis typically involves a few steps:

1. Blood Tests (Serology)

These tests check for antibodies that are often elevated in people with celiac disease:

• tTG-IgA (Tissue Transglutaminase Antibodies – IgA): The most common and reliable initial screening test.
  
• Total IgA: This is done alongside tTG-IgA to check for IgA deficiency, which can affect test accuracy.
  

If the blood tests suggest celiac disease, your healthcare provider may refer you to a specialist for further evaluation.

2. Small Intestine Biopsy

A small intestine biopsy is considered the gold standard for confirming celiac disease. It’s done during an upper endoscopy, where a thin tube with a camera is passed through the mouth to the small intestine. Tiny tissue samples are taken to look for damage to the intestinal villi (the nutrient-absorbing lining of the gut).

3. Genetic Testing

This test checks for specific genes – HLA-DQ2 and HLA-DQ8 – which are necessary for developing celiac disease. If you do not have either gene, it’s very unlikely that you have celiac disease. 

4. Skin Biopsy

If you have a chronic, itchy rash suspected to be dermatitis herpetiformis, a skin biopsy may be done. This involves removing a small piece of skin near the rash to test for gluten-related antibodies. A diagnosis of dermatitis herpetiformis is considered confirmation of celiac disease.

What’s the Treatment?

Right now, the only treatment for celiac disease is a strict, lifelong gluten-free diet. A small quantity of gluten is enough to trigger an immune response and cause damage to the small intestine, even if you don’t notice symptoms right away.

Avoiding gluten means eliminating all foods that contain wheat, rye, and barley (and regular oats), as well as watching out for cross-contamination and hidden sources in processed foods, medications, and supplements. It can take time to adjust, and guidance from a registered dietitian can be tremendously helpful during this transition.

Once gluten is removed from the diet, the intestine can begin to heal, and symptoms usually improve over time. Nutritional deficiencies (such as low iron, calcium, vitamin D, or B vitamins) may also need to be corrected with supplements or dietary changes.

Living with Celiac: You’re Not Alone

A celiac disease diagnosis can be life-changing – but with time, support, and the right information, it becomes easier to manage. Many people feel better once they start to make changes and understand their condition.

In our next post, we’ll take a closer look at what it really means to follow a gluten-free diet – your most important tool for managing celiac disease and protecting your health.

What are your biggest questions about celiac disease, or is there a specific topic you’d like us to cover next? Share your thoughts in the comments below!