In this post, I discuss new research on the complicated link between autoimmune diseases and . Autoimmune diseases are chronic illnesses in which a host’s immune system fails to distinguish between self and foreign cells, and as a result attacks the body’s tissues and organs. Eating disorders (e. ., anorexia nervosa, bulimia nervosa, binge eating) are conditions associated with abnormal consumption of and relationship to food.

According to Hedman and colleagues, as explained in a paper published in the July 2019 issue of Journal of Child Psychology and , there is a strong relationship between eating disorders and autoimmune diseases, especially in women.1

Analysis of the relationship between autoimmune and eating disorders

The sample in the study by Hedman and colleagues was chosen from a cohort of over two and a half million participants, individuals born in Sweden between 1979 and 2005. People in this large group were followed either to the end of the follow-up period (December 2013) or until one of the following events took place: migration, death, receiving a diagnosis for an eating condition or autoimmune disease. Therefore, the follow-up period ranged from 1 month to 22 years.

Of the original group, more than 26,000 were diagnosed with an ; over 110,000, with an autoimmune disorder.

Eating disorders occurred in 2% of women but only 0.1% of men. Put differently, the great majority (94%) of people with an eating condition were female.

Women were also more likely, than men, to have an autoimmune disease (62,605 vs 48,796).

The most prevalent autoimmune illnesses in the sample were celiac disease (related to malabsorption and intestinal sensitivity to Gluten), type 1 diabetes (related to the body’s inability to produce sufficient insulin), and psoriasis (a skin condition).

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Analysis of the relation between eating disorders and autoimmune illnesses showed that in both men and women, previous autoimmune illness was associated with an increased risk for eating disorders.

In men, prior diagnosis of arthritis (a disease characterized by joint pain and stiffness), celiac disease, type 1 diabetes, lupus (an autoimmune disease), psoriasis, Crohn’s disease (an inflammatory disease of the bowels), and ulcerative colitis (another common inflammatory bowel disease) increased the risk of a subsequent autoimmune condition.

In women, there was an elevated risk for after a diagnosis of Crohn’s disease, celiac disease, and type 1 diabetes. The risk for any eating condition was also elevated after a previous diagnosis of Crohn’s disease, celiac disease, ulcerative colitis, type 1 diabetes, and psoriasis.

In women only, the opposite relationship was also found. That is, women receiving a diagnosis of eating disorders were at greater risk for subsequent autoimmune disease.

Women diagnosed with any eating disorder had a 114% increased risk of being diagnosed with an autoimmune illness in the following year—48% between the first and fourth year, and 32% after that. For instance, any eating condition increased the risk for celiac disease (189%) and Crohn’s disease (202%) one year after the diagnosis.

Why are autoimmune diseases and eating disorders linked?

The bidirectional nature of the link between autoimmune diseases and eating disorders suggests that the two share either the same underlying mechanism or some factor that affects the risk for both types of diseases.

Immune function dysregulation may be one such shared mechanism. For instance, some immune-related biological properties or biological factors—such as abnormal concentrations of estrogen and cytokines, low /diversity of gut microbiota—might be more common in some individuals with eating disorders.

Environmental and behavioral factors might play a role too. Consider type 1 diabetes: Diabetes self-care requires behaviors like portion control, monitoring of blood sugar levels, exercise, tracking of carbohydrate intake, and so forth; these behaviors have the potential to become excessive and pathological, and to increase the likelihood of developing eating disorders.

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Similarly, in celiac disease, the “permanent [gluten-free] dietary restriction and vigilant monitoring necessary can foster preoccupation with, and about eating, potentially increasing the risk for pathological eating behaviors.” In addition, the “dietary changes can result in weight gain...which may increase body dissatisfaction and potentially induce restricting and/or purging behaviors” (p. 808).1

In short, the complex relationship between eating disorders and autoimmune diseases may be due to various biological and environmental factors. Therefore, it is advisable to monitor patients with anorexia nervosa, , or other eating conditions because of their increased risk for autoimmune diseases; and to monitor those diagnosed with celiac disease, type 1 diabetes, and other autoimmune illnesses, given that they are at an increased risk for eating disorders.