Eating Disorders- Could it be your Gut?
Written by Ritika Jhawar
Edited by Claire Fargeix
July 31st 2021
Edited by Claire Fargeix
July 31st 2021
Eating disorders are one of the strongest, yet ill-perceived mental illnesses that have become increasingly prevalent throughout society— especially with influenceable teenage girls. Eating disorders, as defined by the American Psychiatric Association, are a “group of mental illnesses that manifest with disturbance to feeding behaviors and body weight regulation” (2013). There are numerous diagnoses within this category, but many share the same symptoms of binging, purging, and calorie restriction. Previously, scientists looked at neurological and physiological alterations as the sole causes for the development of an eating disorder, but new research is now pointing to the importance of physiological traits too.
A biological theory to explain causes of eating disorders has emerged: what if it is your gut? Having healthy gut bacteria is essential for bodily functions! States of dysbiosis can cause an increased risk for disease, including type 2 diabetes, Alzheimer's disease, and more (Budhram et al., 2016; Pistollato et al., 2016; Woting et al., 2016). Different types of bacteria have different needs; some prefer carbohydrates, others favor protein and animal fat. As a result, dominance of certain bacteria can have increased food source preferences, thus causing the host to change their diet. Animal studies have shown that gut bacteria can impact the activity of appetite-regulating hormones, regulating the secretion of satiety and hunger-inducing hormones (Wisse et al., 2007; Von Meyenburg, et al., 2004). This can influence what the host consumes and the frequency of consumption (Alcock et al., 2014).
Neurologically, gut microbes have been proven to transmit behavioral traits, allowing the host to develop depressive-like symptoms (Hoban et al., 2016). They have this influence through the hypothalamic-pituitary-adrenal (HPA) axis, producing different neurotransmitters and neuromodulators, thus indirectly the bacteria can influence our central nervous system (Luczynski et al., 2016).
So if the data shows that gut microbiota vary in dominance within those who show signs of an eating disorder, how does it get damaged in the first place? Scientists decided to do an experiment looking at stress responses in rhesus monkeys. They showed that monkeys with chronic childhood social stress and early life stress were more likely to have stress-induced dysbiosis (Bailey et al., 1999). This ties stress as an important factor when it comes to the regulation of a healthy and proper gut.
There has also been research done regarding recovery. One method to treat eating disorders is nutritional rehabilitation (refeeding). This treatment aims to bring affected individuals back to a healthy weight. The process involves using higher calorie meals, and enteral feeding if required (Garber et al., 2016). Through this process, gut microbiota move towards being more diverse but still carry different bacterial ratios from healthy controls (Kleiman et. al, 2015, Mack et. al, 2016).
More recently, there has been growing evidence and reasoning to use microbiome-based treatments for those suffering from eating disorders. This process is not as simple as it seems. Scientists still need to be able to isolate different gut microbiota depending on the eating disorder, and then try to see their relevance towards the disease. After testing in vitro and animal models, they would be ready to see how to use this treatment in individuals (Zhao, 2013). If successful, this method would help many who are still struggling to recover using current techniques. It definitely gives patients hope though, as it provides a new form of therapy to help those trying to get back to a healthier state.
Sources
Alcock, J., Maley, C. C., & Aktipis, C. A. (2014). Is eating behavior manipulated by the gastrointestinal microbiota? Evolutionary pressures and potential mechanisms. BioEssays : news and reviews in molecular, cellular and developmental biology, 36(10), 940–949. https://doi.org/10.1002/bies.201400071
American Psychiatric Association. The Diagnostic and Statistical Manual of Mental Disorders, 5th ed.; American Psychiatric Publishing: Arlington, VA, USA, 2013.
Bailey, M. T., Dowd, S. E., Galley, J. D., Hufnagle, A. R., Allen, R. G., & Lyte, M. (2011). Exposure to a social stressor alters the structure of the intestinal microbiota: implications for stressor-induced immunomodulation. Brain, behavior, and immunity, 25(3), 397–407. https://doi.org/10.1016/j.bbi.2010.10.023
Budhram, A., Parvathy, S., Kremenchutzky, M., & Silverman, M. (2017). Breaking down the gut microbiome composition in multiple sclerosis. Multiple sclerosis (Houndmills, Basingstoke, England), 23(5), 628–636. https://doi.org/10.1177/1352458516682105
Garber, A. K., Sawyer, S. M., Golden, N. H., Guarda, A. S., Katzman, D. K., Kohn, M. R., Le Grange, D., Madden, S., Whitelaw, M., & Redgrave, G. W. (2016). A systematic review of approaches to refeeding in patients with anorexia nervosa. The International journal of eating disorders, 49(3), 293–310. https://doi.org/10.1002/eat.22482
Hoban, A. E., Moloney, R. D., Golubeva, A. V., McVey Neufeld, K. A., O'Sullivan, O., Patterson, E., Stanton, C., Dinan, T. G., Clarke, G., & Cryan, J. F. (2016). Behavioural and neurochemical consequences of chronic gut microbiota depletion during adulthood in the rat. Neuroscience, 339, 463–477. https://doi.org/10.1016/j.neuroscience.2016.10.003
Kleiman, S. C., Watson, H. J., Bulik-Sullivan, E. C., Huh, E. Y., Tarantino, L. M., Bulik, C. M., & Carroll, I. M. (2015). The Intestinal Microbiota in Acute Anorexia Nervosa and During Renourishment: Relationship to Depression, Anxiety, and Eating Disorder Psychopathology. Psychosomatic medicine, 77(9), 969–981. https://doi.org/10.1097/PSY.0000000000000247
Luczynski, P., McVey Neufeld, K. A., Oriach, C. S., Clarke, G., Dinan, T. G., & Cryan, J. F. (2016). Growing up in a Bubble: Using Germ-Free Animals to Assess the Influence of the Gut Microbiota on Brain and Behavior. The international journal of neuropsychopharmacology, 19(8), pyw020. https://doi.org/10.1093/ijnp/pyw020
Mack, I., Cuntz, U., Grämer, C., Niedermaier, S., Pohl, C., Schwiertz, A., Zimmermann, K., Zipfel, S., Enck, P., & Penders, J. (2016). Weight gain in anorexia nervosa does not ameliorate the faecal microbiota, branched chain fatty acid profiles, and gastrointestinal complaints. Scientific reports, 6, 26752. https://doi.org/10.1038/srep26752
Pistollato, F., Sumalla Cano, S., Elio, I., Masias Vergara, M., Giampieri, F., & Battino, M. (2016). Role of gut microbiota and nutrients in amyloid formation and pathogenesis of Alzheimer disease. Nutrition reviews, 74(10), 624–634. https://doi.org/10.1093/nutrit/nuw023
Von Meyenburg, C. Hrupka, B. H., Arsenijevic, D., Schwartz, G. J., Landmann, R., & Langhans, W. (2004). Role for CD14, TLR2, and TLR4 in bacterial product-induced anorexia. American journal of physiology. Regulatory, integrative and comparative physiology, 287(2), R298–R305. https://doi.org/10.1152/ajpregu.00659.2003
Wisse, B. E., Ogimoto, K., Tang, J., Harris, M. K., Jr, Raines, E. W., & Schwartz, M. W. (2007). Evidence that lipopolysaccharide-induced anorexia depends upon central, rather than peripheral, inflammatory signals. Endocrinology, 148(11), 5230–5237. https://doi.org/10.1210/en.2007-0394
Woting, A., & Blaut, M. (2016). The Intestinal Microbiota in Metabolic Disease. Nutrients, 8(4), 202. https://doi.org/10.3390/nu8040202
Zhao L. (2013). The gut microbiota and obesity: from correlation to causality. Nature reviews. Microbiology, 11(9), 639–647. https://doi.org/10.1038/nrmicro3089
Image Source: “Gut Bacteria” by National Institute of Allergy and Infectious Diseases, National Institutes of Health licensed under CC BY-NC 2.0