From Ayurveda to the teachings of Hippocrates, medicine’s earliest traditions advanced a belief that the gut was the foundation of all health and disease. It wasn’t until recently, however, that Western medicine has adopted the notion of gut-barrier dysfunction as a pathologic phenomenon critical to not only digestive health but also chronic allergic, inflammatory, and autoimmune disease.
To learn more, Medscape contributor Akash Goel, MD, interviewed Elena Ivanina, DO, MPH, an integrative gastroenterologist, on the role of the gut barrier. Dr. Ivanina is the founder of the Center for Integrative Gut Health and the former director of Neurogastroenterology and Motility at Lenox Hill Hospital in New York. She runs the educational platform for all things gut health, gutlove.com.
What is the role of the gut barrier in overall health and disease?
The gut contains the human body’s largest interface between a person and their external environment. The actual interface is at the gut barrier, where there needs to be an ideal homeostasis and selectivity mechanism to allow the absorption of healthy nutrients, but on the other hand prevent the penetration of harmful microbes, food antigens, and other proinflammatory factors and toxins.
The gut barrier is made up of the mucus layer, gut microbiome, epithelial cells, and immune cells in the lamina propria. When this apparatus is disrupted by factors such as infection, low-fiber diet, antibiotics, and alcohol, then it cannot function normally to selectively keep out the harmful intraluminal substances.
Gut-barrier disruption leads to translocation of dangerous intraluminal components, such as bacteria and their components, into the gut wall and, most importantly, exposes the immune system to them. This causes improper immune activation and dysregulation, which has been shown to lead to various diseases, including gastrointestinal inflammatory disorders such as inflammatory bowel disease (IBD) and celiac disease, systemic autoimmune diseases such as multiple sclerosis and rheumatoid arthritis, and metabolic diseases such as obesity and diabetes.
Is disruption of this barrier what is usually referred to as “leaky gut”?
Leaky gut is a colloquial term for increased intestinal permeability or intestinal hyperpermeability. In a 2019 review article, Dr. Michael Camilleri exposes leaky gut as a term that can be misleading and confusing to the general population. It calls upon clinicians to have an increased awareness of the potential of barrier dysfunction in diseases, and to consider the barrier as a target for treatment.
Is leaky gut more of a mechanism of underlying chronic disease or is it a disease of its own?
Intestinal permeability is a pathophysiologic process in the gut with certain risk factors that in some conditions has been shown to precede chronic disease. There has not been any convincing evidence that it can be diagnosed and treated as its own entity, but research is ongoing.
In IBD, the Crohn’s and Colitis Canada Genetic, Environmental, Microbial Project research consortium has been studying individuals at increased risk for Crohn’s disease because of a first-degree family member with Crohn’s disease. They found an increased abundance of Ruminococcus torques in the microbiomes of at-risk individuals who went on to develop the disease. R. torques are mucin degraders that induce an increase in other mucin-using bacteria, which can contribute to gut-barrier compromise.
In other studies, patients have been found to have asymptomatic intestinal hyperpermeability years before their diagnosis of Crohn’s disease. This supports understanding more about the potential of intestinal hyperpermeability as its own diagnosis that, if addressed, could possibly prevent disease development.