In a large study of more than 2,000 Finnish people with eating disorders, investigators found they were more likely to have an autoimmune disease compared with healthy people.
When you have an autoimmune disease, your immune system incorrectly attacks and destroys healthy cells in your body.
"I was surprised about the robust link that we found between autoimmune diseases and eating disorders," lead author Anu Raevuori, MD, PhD, from the Department of Public Health at the University of Helsinki, Finland, tells Medscape Medical News.
The immune system appears to contribute to the start and continued problems of eating disorders, at least in this group of patients, the researchers say.
Also, the people with eating disorders were more than twice as likely to have endocrine diseases, especially type 1 diabetes, and GI disorders, particularly Crohn's disease.
The study was published online Aug. 22 in PLoS One.
Over the course of about 16 years, the researchers examined 2,342 people for bulimia nervosa, anorexia nervosa, and binge eating disorder. The people were getting treated at an eating disorder unit in Helsinki.
Each patient was then compared with four age- and sex-matched healthy people. Also, data on 30 autoimmune diseases from a hospital discharge register from 1969 to 2010 were analyzed.
Results showed that 8.9% of the people with eating disorders and 5.4% of healthy people had been diagnosed with at least one autoimmune disease by the end of follow-up.
We’re not sure why, but autoimmune disease was more common in men with bulimia nervosa than for women with the disorder.
Raevuori says she didn't want to "belittle the psychological aspects of these disorders, which undoubtedly also play an important role." Instead, the findings lead to the questions of what is psychological and what is biological, "and to what extent are they separable."
More on Autoimmune Diseases
Previous research has suggested that autoimmune diseases and severe infections are risk factors for mood disorders overall and for schizophrenia specifically.
The immune system has also been recognized as playing a role in disorders including autism spectrum disorders, ADHD, obsessive-compulsive disorder, and post-traumatic stress disorder.
Dr. Raevuori and 4 of the other study authors report no relevant financial relationships. The remaining 3 have reported potentially competing interests, which are listed in full in the original article.