BRAIN - VAGUS NERVE - GUT CONNECTION
By Stacy Seslowsky, RD, LDN, MS
Common symptoms of irritable bowel syndrome (IBS) are gastrointestinal (GI) distress, abdominal pain, changes in motility, depression, and anxiety. Mood disorders are highly correlated with GI disorders and we can appropriately ask what comes first, the chicken or the egg?
The gut-brain connection has been extensively studied and we, as dietitians and nutritionists focus tremendous amounts of energy on improving the integrity of the gut lining, promoting the density and diversity of the gut microbiome, replenishing nutrients in the diet, and eliminating intolerable foods, but we may be missing an important piece of this puzzle.
"We are missing an important piece of this puzzle"
The vagus nerve is the highway connecting the brain and the gut. The familiar term, “rest and digest” is routinely used to describe the role of the vagus nerve and the parasympathetic system. As depicted in the diagram above, the vagus nerve is responsible for the motility of food and bacteria in the downward direction. Additionally, it inhibits the secretion of inflammatory cytokines in the intestine and the liver. Inadequate vagus nerve stimulation causes problems with digestion AND inflammation. A loop mechanism begins when dysbiosis and gut inflammation reduce vagal motor outflow. This is a vicious cycle amplifying GI distress, reducing neurotransmitter firing in the brain which results in depression and anxiety.
"...guiding our patients to routinely implement strategies to stimulate the vagus nerve should become a top priority."
By teaching our patients to routinely stimulate the vagus nerve, we may take significant strides forward in helping our GI, depressed patients to experience maximum relief. Transcutaneous electrical nerve stimulation (TENS) was used to trigger the vagus nerve in a randomized controlled trial and the effects were increased GI motility and reduced somatic pain sensitivity [1]. Similarly, TENS was applied to adolescent patients with IBS and 59% of the study subjects experienced significant reductions in pain [2].
Cristancho et al. observed significantly decreased depression in patients suffering from extremely difficult-to-treat depressive disorder when implanted with vagus nerve stimulating devices [3]. Furthermore, stimulating the vagus nerve may have positive implications in rheumatoid arthritis, lupus, and other autoimmune or inflammatory conditions [4]. Meditation, yoga, Qigong, humming, gargling, acupuncture, massage, alternating between hot and cold water showers, intermittent fasting, and the use of a TENS device are powerful ways to stimulate the vagus nerve. I would argue that guiding our patients to routinely implement strategies to stimulate the vagus nerve should become a top priority alongside healing the gut, optimizing the diet, and removing inflammatory foods.
"We may take significant strides forward in helping our patients who struggle with GI distress, pain, depression, and anxiety to experience maximum relief."
References: 1. Frøkjaer JB, Bergmann S, Brock C, et al. Modulation of vagal tone enhances gastroduodenal motility and reduces somatic pain sensitivity. Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society. 2016;28(4):592-598. doi:10.1111/nmo.127603. 2. Amornluck Krasaelap, Manu R. Sood, B.U.K. Li, Rachel Unteutsch, Ke Yan, Melodee Nugent, Pippa Simpson, Katja Kovacic, Efficacy of Auricular Neurostimulation in Adolescents With Irritable Bowel Syndrome in a Randomized, Double-Blind Trial, Clinical Gastroenterology and Hepatology, Volume 18, Issue 9, 2020, Pages 1987-1994.e2, ISSN 1542-3565,Cristancho P, 3. Cristancho MA, Baltuch GH, Thase ME, O'Reardon JP. Effectiveness and safety of vagus nerve stimulation for severe treatment-resistant major depression in clinical practice after FDA approval: outcomes at 1 year. J Clin Psychiatry. 2011 Oct;72(10):1376-82. doi: 10.4088/JCP.09m05888blu. PMID: 21295002. 4. Das UN. Can vagus nerve stimulation halt or ameliorate rheumatoid arthritis and lupus? Lipids Health Dis. 2011 Jan 24;10:19. doi: 10.1186/1476-511X-10-19. PMID: 21261967; PMCID: PMC3037330.