Eating disorders (EDs) such as binge eating disorder, anorexia nervosa (AN), and bulimia nervosa (BN) affect up to 2.8% of adults and 2.7% of adolescents in the United States, with prevalence rates that are 2 to 5 times higher among women compared with men.1 While EDs are primarily considered psychiatric disorders, they are associated with a range of physical comorbidities, including gastrointestinal (GI) disorders.2,3 EDs can cause or exacerbate various GI symptoms, and GI disorders can lead to or worsen disordered eating behaviors.
The topics of recent studies illuminate the bidirectional nature of this connection.3-6 In a case-control study published in May 2021 in the International Journal of Eating Disorders, researchers investigated the prevalence of disorders of gut-brain interaction (DGBI), using the ROME III questionnaire, among 765 patients with EDs (92.2% women) compared with 1240 control participants (98.9% women).
The results demonstrated that among patients with AN, BN, and multiple eating disorders (mED), 88.2%, 94.7%, and 95.5%, reported at least 1 DGBI, respectively; and 34.8%, 38.8%, and 48.7% reported 3 or more, respectively. Among control participants, 79.8% reported at least 1 DGBI and 9.1% reported 3 or more (q <.05).3
High levels of current ED symptoms were associated with a higher mean number of DGBI (3.03-3.34) compared with low levels of symptoms (1.60-1.84). Functional bowel disorders represented the most prevalent category of DGBI, and irritable bowel syndrome (IBS) was the most commonly reported disorder (43.9% to 58.8%).3
A study published in the same journal in November 2020 examined DGBI symptoms among 168 pediatric and adult outpatients with EDs (71% female) and found at least 1 bothersome GI symptom in 72% of participants, with 39% meeting criteria for a DBGI on a modified Rome IV questionnaire.5 The most common DBGI was functional dyspepsia, a post-prandial distress syndrome subtype. DGBI were less prevalent among patients with avoidant/restrictive food intake disorder (ARFID) (30%) compared with those with EDs associated with shape or weight concerns (45%; X2 =3.61, P =.058, Cramer’s V =.147).
Conversely, a study published in October 2021 in Neurogastroenterology and Motility explored the frequency and nature of ED symptoms in a sample of 99 adults (77.1% women) with DGBI. Analyses revealed ARFID symptoms in 39.8% of participants based on scores on a modified ARFID Canadian Paediatric Surveillance Program Questionnaire, and clinically significant shape/weight-motivated ED symptoms in 12.9% of participants based on global scores greater than or equal to 4.0 on the ED Examination Questionnaire. In addition, the ED symptoms were associated with higher scores on self-report measures of depression, generalized anxiety, and pain interference.6
With the close link between GI disorders and EDs, individuals with EDs often “seek gastroenterological health care at some point in their illness, with many seeking this care even before they seek treatment for and/or [are] diagnosed with their eating disorder,” Werlang et al wrote in a 2021 paper published in the American Journal of Gastroenterology.7 “As such, the gastroenterology provider is in a unique position to identify, manage, and facilitate treatment for an eating disorder early in the course of the illness.”
For further insights regarding this topic and related clinical implications for gastroenterologists, we interviewed Cynthia Bulik, PhD, professor of nutrition at the Gilling School of Global Public Health at the University of North Carolina in Chape Hill, founding director of the UNC Center of Excellence for Eating Disorders, and director of the Centre for Eating Disorders Innovation at Karolinska Institutet in Stockholm, Sweden; and Helen Burton Murray, PhD, psychologist and director of the GI Behavioral Health Program in the Massachusetts General Hospital Center for Neurointestinal Health, and member of the faculty in psychology at Harvard Medical School in Boston.
Among the extensive body of work by both experts, Dr Bulik is a co-author of the May 2021 study3 described above, and Dr Burton Murray is the first author of the studies5,6 published in November 2020 and October 2021.
What does the available evidence suggest about the relationship between EDs and GI disorders?
Dr Bulik: The relation between EDs and DGBI (formerly known as functional gastrointestinal disorders) is a very critical area of study that deserves far more attention than it has received. The direction of causation goes both ways: We know that some individuals who have GI illnesses that require them to restrict their eating to minimize symptoms can precipitate EDs. We also know that EDs and their component behaviors — restricting, binge-eating, self-induced vomiting, and laxative abuse, for example — can have direct adverse effects on GI functioning.
Our recent study had one of the larger sample sizes in this area and shows high rates of DGBI in individuals with eating disorders.3 We have also shown in children that both prolonged diarrhea and constipation are more common in children who develop disordered eating.8
Dr Burton Murray: We know that these disorders commonly co-occur. Disordered eating symptoms have been reported in 5% to 44% of individuals with GI disorders.9 More recently, rates of ARFID have been investigated, and pediatric and adult studies show that 23% to 40% of individuals with DGBI have significant ARFID symptoms.10,11
Studies on ARFID symptoms in organic/structural GI conditions like inflammatory bowel diseases (IBDs) and celiac disease have been conducted but have only used self-report screeners, which likely have overinflated rates. Overall, fear conditioning around eating is hypothesized to contribute to ARFID development in GI disorders.12
In individuals with EDs, both chronic and acute GI symptoms are common, and acute medical (including GI) complications are well known. However, DGBI are less studied in this population. One study showed that DGBI were present among 97% of ED inpatients at admission but then decreased to 77% one year later.13
In a recent study from our group in an outpatient ED sample, DGBI symptoms were present in approximately 39% of patients, with similar rates in ARFID and other ED presentations.6
There is also some growing research that suggests bidirectional relationships between the onset of EDs and GI disorders. For example, a large population-based study showed that autoimmune conditions related to the GI tract (IBDs and celiac disease) significantly increased the subsequent risk for developing an ED, and this relationship also existed for EDs, which significantly increased risk for developing future IBDs or celiac onset.14
What are the underlying mechanisms for some of the common GI disorders observed in patients with EDs?
Dr Bulik: There are some shared genetic factors between anorexia nervosa and some GI illnesses.15 We also have a hypothesis about early visceral conditioning and anorexia nervosa.16
One thing we have seen more of during the pandemic is the impact of COVID-19-related anxiety (and even COVID-19 itself) on GI function in our patients. Anxiety is one of the “third variables” that can play a causal role in both GI problems and EDs, and it needs to be assessed and treated appropriately.
Dr Burton Murray: I can speak to DGBI, which don’t involve structural or organic abnormalities (i.e., there is no cancer, ulcer, etc.). Instead, there is a signaling problem between the GI tract and the brain, which may include aspects such as 1 or more of the below:
- “False alarm” GI sensations or the “dial” on normal GI sensations is turned up higher than it needs to be. (e.g., feeling extremely full after eating a small amount). A combination of visceral hypersensitivity and altered visceral interoception likely play a role. In patients with EDs, there may be lower toleration of and worry around the GI sensations, leading to attempts to prevent them with changes in eating behavior, such as avoiding eating certain types or amounts of food. Some patients with EDs may also have an overvaluation of their body shape or weight and worry that some GI symptoms they experience, such as bloating and distension, may mean they have gained weight.
- Altered motility: Some examples we see frequently in patients with comorbid EDs are poor gastric accommodation, slow colonic transit, and pelvic floor dysfunction.
In these cases, our team uses behavioral treatments in combination with neuromodulators (medications such as tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and gabapentin) and other therapies when indicated (e.g., pelvic floor physical therapy or other medications that address altered motility). The primary goals in behavioral treatments are to challenge the predictions patients may have around their GI symptoms and to increase toleration of GI sensations.
What are key recommendations for GI physicians about how to approach this comorbidity in practice?
Dr Bulik: The more we can get GI [physicians] working with ED specialists from early on, the better. The National Center of Excellence for Eating Disorders is developing [the] Screening, Brief Intervention, and Referral to Treatment for Eating Disorders (SBIRT-ED) that can be used as a brief screen for patients.
I would also encourage GI [physicians] to include EDs (anorexia nervosa, bulimia nervosa, binge-eating disorder, [and] other eating disorders) on their pre-visit screening checklists and to ask about the patient and family history of these illnesses. We need to get to the point where we are as comfortable checking these boxes as we are clicking history of cancer or heart disease in ourselves and relatives.
Then, if a box is checked, make sure you ask about it gently and respectfully, as you would with any other medical illness. For example, “I see you checked off anorexia nervosa. Tell me a little more about that.”
Dr Burton Murray: Given the high comorbidity rates, screening all patients for EDs is vital. The questions in the SCOFF can be used.17 Also, asking about fear around eating due to GI symptoms can help screen for ARFID. While there are no cutoffs yet in GI samples, items from the Nine Item ARFID Screen or the Fear of Food Questionnaire may help clinicians with this questioning.18
Be cautious around the use of diet interventions. If they are indicated, make sure to regularly assess for weight loss, micronutrient deficiencies, and quality of life impacts. The American College of Gastroenterology recently published guidelines for IBS management, from which I think principles on the screening for EDs and malnutrition can apply to all GI disorders.19
What are additional needs in terms of physician education and research regarding the ED-GI link?
Dr Bulik: We definitely need more research funded to explore the intersection of GI problems and EDs across the board. There is frighteningly little research on the long-term effects of EDs on the GI system, such as the effect of prolonged self-induced vomiting on Barret’s esophagus and esophageal cancers, and the effect of prolonged laxative abuse on bowel function and intestinal microbiota and morphology.
We need to educate GI [physicians] and other [clinicians] who deal with GI problems — family physicians, general practitioners, pediatricians, endocrinologists — on current thinking about EDs: These are not choices. People don’t choose to have anorexia nervosa, bulimia nervosa, or binge-eating disorder. We now have strong evidence that genetic factors are involved, and at least in the case of anorexia nervosa, our genetic work is implicating both psychiatric and metabolic factors.
It is critically important for GI physicians to not view the problems that people with EDs present with as something that they self-imposed. Sadly, I have witnessed many cases where a GI specialist has not had appropriate empathy for the suffering that is associated with EDs.
Likewise, people who work with EDs need to not write off every GI complaint to the ED. We need to work hand in hand and communicate well in order to address these patients’ problems. Greater education, more experience, and more research that cross-cuts the 2 domains are needed. For example, we would love to have GI fellows rotate on our inpatient units!
Of note, we are in the middle of the largest genetic investigation of EDs ever, the Eating Disorders Genetics Initiative. It would be wonderful if more physicians would refer their patients to the study. It is all online and includes a simple at-home saliva sample for DNA.
Dr Burton Murray: Most of the research in this area consists of cross-sectional studies. We need more prospective research to identify why EDs and GI disorders share a link in a subset of individuals.
We are also conducting research that investigates whether avoidant/restrictive food intake actually perpetuates DGBI, specifically in functional dyspepsia. Our hypothesis is that if we target avoidant/restrictive food intake, the GI disorder will improve.
Educating clinicians about the pitfalls that diet interventions may have (whether self-imposed by patients or prescribed) for a subset of patients is an important and growing effort — as evidenced by the ACG guidelines for IBS, for example.
Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
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