The Surprising Links Between Celiac Disease and Anorexia

Women who have one condition are more likely to have the other

Woman on gluten free diet
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At first glance, celiac disease—which occurs when consumption of the protein gluten triggers intestinal damage—appears to have little in common with the eating disorder anorexia nervosa. Superficially, they both involve eating, but celiac is an autoimmune condition, and anorexia is considered an emotional disorder.

However, researchers have uncovered what they say appear to be links between the two conditions.

Specifically, women who previously have been diagnosed with celiac disease are more likely to also be diagnosed with anorexia, and conversely, women who previously have been diagnosed with anorexia are more likely to later be diagnosed with celiac.

It's not clear why this occurs—several factors, including genetics, may play a role. But the research does indicate the need for heightened awareness of the potential link, and for the issues facing someone who has both conditions.

Celiac and Anorexia: What Are the Connections?

Celiac disease is an autoimmune condition that's triggered when you consume a food or a drink containing one of the gluten grains (wheat, barley, or rye). Your immune system reacts to the gluten protein by attacking the lining of your small intestine, potentially leading to a wide variety of symptoms and nutritional deficiencies. It's not clear what causes celiac diseasegenetics play a strong role, but researchers are also trying to identify potential triggers.

Meanwhile, it's also not clear what exactly causes anorexia nervosa. Eating disorders appear to run in families, which suggests that there are genetic links, but environmental and emotional factors also may play strong roles.

Celiac disease and anorexia nervosa are not rare conditions—celiac affects slightly less than 1 percent of the U.S. population, while anorexia may affect up to 1 percent of women over their lifetimes.

Both conditions are more common in women than in men.

Over the years, clinicians have noted several cases of the two conditions occurring together in the same person, prompting researchers to look more closely at potential links. In addition, researchers looking at the genetics of celiac disease, type 1 diabetes (another autoimmune condition), and anorexia nervosa found shared genetic factors among the three, suggesting what the study called "common molecular pathways" for those conditions.

Higher Risks for Both Celiac and Anorexia

A study from Sweden published in the medical journal Pediatrics examining these links looked at nearly 18,000 women who had been diagnosed with celiac disease, comparing them to nearly 90,000 women without the condition.

The researchers found that women with celiac disease were 1.46 times more likely to also be diagnosed with anorexia nervosa in the first year following their celiac diagnosis, and 1.31 times more likely to be diagnosed with anorexia beyond the first year following their celiac diagnosis.

Women were even more likely to be diagnosed first with anorexia and then with celiac: having a previous anorexia diagnosis made an eventual celiac diagnosis 2.18 times more likely, the study found.

The analysis didn't identify any increased risks in men, but the researchers warned that the study wasn't big enough to uncover potential risks in men.

Several factors could have contributed to the increased risk in women, the authors wrote. First, it's possible that someone with celiac disease could have been misdiagnosed with anorexia, since both conditions can cause weight loss and malnutrition. Second, there's the possibility of what researchers call "surveillance bias," which means people under closer medical scrutiny are more likely to have medical conditions identified. And third, shared risk factors, including genetics, could play a role.

What Happens Now?

It's possible that being diagnosed with celiac disease—which requires a strict gluten-free diet to control—could trigger an eating disorder in someone who previously didn't have one.

"Not infrequently, an eating disorder begins with well-meaning, self-imposed attempts to 'eat healthily' by eliminating foods perceived to be unhealthy," note Drs. Neville Golden, MD and K.T. Park, both Stanford University pediatricians, in a commentary accompanying the study in Pediatrics. "The present study suggests that excessive focus on diet in patients with celiac disease may lead to development of anorexia nervosa in susceptible individuals."

The fact that researchers found what they called a "bidirectional association"—meaning people diagnosed with one condition were more likely to be diagnosed with the other, regardless of which one was diagnosed first—means physicians should closely monitor people with either celiac disease or anorexia nervosa to watch for the possibility of the other condition developing.

Another concern is that having anorexia makes it harder to follow the gluten-free diet. Those who eat gluten-free know they sometimes are forced to go hungry in situations when there's nothing safe to eat, but that can be dangerous for someone with anorexia. It's also possible, researchers say, that some people with anorexia and celiac knowingly consume gluten-containing products because they will trigger a reaction and subsequent weight loss.

Treating people who have both celiac disease and anorexia nervosa can be challenging, since each condition requires a very different approach. Celiac disease normally is diagnosed by a gastroenterologist, and the person with celiac may see other medical professionals, possibly including a dietitian who specializes in the gluten-free diet. Anorexia nervosa, meanwhile, normally is treated by a team led by a mental health professional, and the person with the condition likely will see a dietitian who specializes in eating disorders. In order to treat both conditions at the same time, medical professionals accustomed to their own approaches will need to work together.

Drs. Golden and Park also say that many people are choosing to go gluten-free without a diagnosis, which poses another potential problem: following the gluten-free diet as a way to disguise an eating disorder. "The interaction between gluten-free diets and eating disorders is an even larger issue," they conclude. "This important study is only the tip of the iceberg."

Sources:

Golden NH and Park KT. Celiac Disease and Anorexia Nervosa—An Association Well Worth Considering. Pediatrics. 2017 Apr 3. Published online March 30, 2017.

Marild K et al. Celiac Disease and Anorexia Nervosa: A Nationwide Study. Pediatrics. 2017 Apr 3. Published online March 30, 2017.

Mostowy J et al.  Shared Genetic Factors Involved in Celiac Disease, Type 2 Diabetes and Anorexia Nervosa Suggest Common Molecular Pathways for Chronic Diseases. PLoS One. 2016 Aug 2;11(8):e0159593. 

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