Celiac disease after 40: 5 myths that can delay a diagnosis

If you picture celiac disease, you might picture a child who struggles to gain weight, or someone doubled over after a slice of bread. That picture is incomplete, and it's one reason many adults with celiac disease go years without a diagnosis.

Celiac disease is a permanent immune reaction to gluten, the protein in wheat, barley and rye, and it's marked by injury to the small intestine (Rubio-Tapia et al., 2023). Here are five common beliefs about it, and what the research actually shows.

Myth 1: Celiac disease starts in childhood

Fact: it can develop in adulthood, including later in life. A US study tested blood samples collected from the same group of 3,511 adults in 1974 and again in 1989. Celiac autoimmunity rose from about 1 in 501 people to 1 in 219 over those 15 years. The researchers concluded that the increase came from people losing their tolerance to gluten as adults (Catassi et al., 2010).

A Finnish study found a similar pattern in people over 55. When researchers screened the same population again three years later, they found five new biopsy-proven cases among people who had tested negative the first time (Vilppula et al., 2009).

Myth 2: If you had it, you'd know

Fact: most people with celiac disease in the US don't know they have it. In a nationally representative survey of 7,798 people, researchers found celiac disease in 35 participants, and 29 of them were unaware of it. The overall prevalence was 0.71%, or about 1 in 141 people (Rubio-Tapia et al., 2012).

Symptoms can be subtle, and they aren't always digestive. The American College of Gastroenterology describes celiac disease as resembling a multisystem disorder rather than an isolated gut disease (Rubio-Tapia et al., 2023). In the Finnish study of older adults, two of the five new cases had only minor abdominal symptoms, and three had none at all (Vilppula et al., 2009).

Myth 3: Going gluten-free first is a good way to find out

Fact: celiac tests need gluten in your diet to work. Blood tests look for antibodies your immune system makes in response to gluten, and a biopsy looks for the intestinal damage gluten causes. If you've already cut gluten out, results can look normal even if you have celiac disease.

If you've been gluten-free, your doctor may suggest a gluten challenge before testing. In a study of 20 adults with known celiac disease, eating 3 or 7.5 grams of gluten a day for 14 days caused measurable changes in the intestine and in antibody levels in most participants (Leffler et al., 2013).

Cutting gluten first also muddies the picture in another way. In the US survey, most people following a gluten-free diet didn't have a celiac diagnosis (Rubio-Tapia et al., 2012). Feeling better without gluten doesn't answer the question on its own.

Myth 4: A positive blood test is the diagnosis

Fact: in most adults, a biopsy confirms it. Antibody tests, such as tissue transglutaminase, are very helpful for initial screening. But the ACG guideline states that an intestinal biopsy is required to confirm the diagnosis in most patients. A no-biopsy approach is discussed only for selected children (Rubio-Tapia et al., 2023).

So a positive blood test is a reason to see a gastroenterologist, and to keep eating gluten until you do. It isn't a reason to overhaul your diet that same afternoon.

Myth 5: Once you're gluten-free, you're done

Fact: most people do well, but follow-up matters. Treatment is a strict gluten-free diet with lifelong medical follow-up, and most patients respond very well (Rubio-Tapia et al., 2023). When symptoms continue or come back, the guideline calls for a systematic workup, and unintentional gluten exposure is one of the first things to check.

A registered dietitian who knows celiac disease can help with label reading, cross-contact in your kitchen and eating out. That support can make the difference between a diet that works on paper and one that works in real life.

When to ask about testing

It may be worth asking your doctor about a celiac blood test if you have:

• Bloating, diarrhea or abdominal discomfort that has lasted for weeks
• Iron deficiency anemia without a clear cause
• A parent, sibling or child with celiac disease
• Another autoimmune condition, such as autoimmune thyroid disease or type 1 diabetes

Ask before you change your diet. And if you also have red flags, such as weight loss, blood in your stool or trouble swallowing, mention them too, because they may call for more than a celiac test.

Sources

1. Rubio-Tapia A, Hill ID, Semrad C, et al. American College of Gastroenterology guidelines update: diagnosis and management of celiac disease. Am J Gastroenterol. 2023;118(1):59-76. PMID 36602836
2. Catassi C, Kryszak D, Bhatti B, et al. Natural history of celiac disease autoimmunity in a USA cohort followed since 1974. Ann Med. 2010;42(7):530-8. PMID 20868314
3. Vilppula A, Kaukinen K, Luostarinen L, et al. Increasing prevalence and high incidence of celiac disease in elderly people: a population-based study. BMC Gastroenterol. 2009;9:49. PMID 19558729
4. Rubio-Tapia A, Ludvigsson JF, Brantner TL, Murray JA, Everhart JE. The prevalence of celiac disease in the United States. Am J Gastroenterol. 2012;107(10):1538-44. PMID 22850429
5. Leffler D, Schuppan D, Pallav K, et al. Kinetics of the histological, serological and symptomatic responses to gluten challenge in adults with coeliac disease. Gut. 2013;62(7):996-1004. PMID 22619366

This article is for general information and isn't medical advice. Talk to your healthcare provider before starting a gluten-free diet, since it can affect the accuracy of celiac testing.