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Irritable Bowel Syndrome (IBS) And The Vagus Nerve

Updated on December 27, 2022
IBS & Vagus Nerve

Syndrome medically refers to a constellation of signs and symptoms. Therefore, irritable bowel syndrome, commonly called IBS refers to a group of signs and symptoms manifesting as a result of irritation of the digestive tract. Individuals with irritable bowel syndrome commonly present with belching due to excess gas in the bowel, constipation, pains in the abdomen, cramps, and diarrhea (1).

Overview Of Irritable Bowel Syndrome

Irritable bowel syndrome is one of the various types of functional gastrointestinal tract disorders, which are usually due to issues with the gut-brain axis, that is such signs manifest when there is any alteration in the functioning of the brain and the gut working together which results in hypersensitive bowel (1).

Studies have demonstrated that irritable bowel syndrome can be classified into three and each of these classes were dependent on the pattern of bowel movement patients presented with, and certain medications only work for specific types of irritable bowel syndrome, IBS.

Types Of IBS

The different types based on abnormal bowel movements are:

  • Irritable bowel syndrome with constipation: This is otherwise called IBS-C, characterized by a hard and lumpy stool.
  • Irritable bowel syndrome with diarrhea: This is otherwise called IBS-D, characterized by a watery and loose stool.
  • Irritable bowel syndrome with mixed bowel habits: This is otherwise known as IBS-M, characterized by alternating hard and loose stool on the same day (1).

The common causes of irritable bowel syndrome are:

  • Intestinal muscle contraction: intestinal muscle contractions that are stronger and longer than normal can result in irritable bowel symptoms such as diarrhea, gas, and bloating. When the muscle contraction is slow and weak, it results in hard and dry stool, manifesting as constipation (2).
  • Infection: Irritable bowel syndrome can develop after episodes of severe infection either caused by bacteria or viruses, otherwise called gastroenteritis, and it can also be a result of bacteria overgrowth (2).
  • Nervous system disorder: When there are problems affecting the nerves in the digestive system, leading to poorly coordinated signals between the enteric system, that is, the intestines and the brain, causes a proportional body reaction that can alter the digestive process of the body, leading to cramps, diarrhea or constipation (2).

Overview Of The Vagus Nerve

There are twelve cranial nerves in total, each in pairs, and the vagus nerve has been identified as the tenth cranial nerve. The vagus nerve is the principal nerve of the parasympathetic nervous system, performing involuntary body functions such as the control of heart rate, digestive process, and the body’s immunity.

The vagus nerve also has been identified as the longest cranial nerve in the body extending from the brain to the large intestine, the nerves are in pairs left and right. The left vagus nerve journey down the left side of the body while the right vagus nerve travels down the right side of the body (8).

Common Conditions That Affect The Vagus Nerve

The vagus nerve is mostly involved in the following conditions:

  1. Gastroparesis: When a vagus nerve is damaged, food cannot pass from the stomach into the intestines, resulting in gastroparesis. Diabetes, viral infections, abdominal surgery, and scleroderma are just a few conditions that might harm the vagal nerve (8).

In a 2020 study, the effects of vagal nerve stimulation were examined by some researchers in patients with mild to severe gastroparesis who lacked a recognized underlying cause. Participants' symptoms, particularly their capacity to empty their bowels, improved after 4 weeks, indicating that this would be a helpful treatment for others who have this disease (9).

  1. Vasovagal syncope: Fainting is often referred to as syncope. Vasovagal syncope is a condition in which your heart's vagus nerve overreacts to conditions like intense heat, anxiety, hunger, pain, or stress. Orthostatic hypotension is a rapid drop in blood pressure that can leave you feeling lightheaded or faint (8).

Relationship Between The Vagus Nerve And The Digestive System

The vagus nerve plays a very vital responsibility in the process of digestion, while also performing the function of signal transmission from the gut to the brain. So, it won't be surprising that stimulation of the vagus nerve can help to solve quite a several issues related to the digestive system, and one such is irritable bowel syndrome, IBS (3).

The following are specific functions performed by the vagus nerve in each step of the digestion process.

  • Stomach: In the stomach, the vagus nerve aids food grinding and the production of gastric acid in the stomach required for the digestion of food. Consequently, in vagus disorder, the acidic level is low which in turn causes a decrease in the function of the acid, leading to alteration in the process of digestion.
  • Liver: the vagus nerve also aids the proper functioning of the liver. It aids the production of bile which is later transported to the gallbladder, thereafter to the intestine to help in the digestion of fats. Another very effective function of the vagus nerve to the liver is that it helps to aid gluconeogenesis in the liver, which brings about glucose production to help in the control of the blood sugar level, and it also helps in food and toxins metabolisms (3).
  • The intestines: The relationship between the vagus nerve and the digestive system will not be completely discussed without stating the intestines. The vagus nerve controls the affairs of both the small intestines and the large intestines. The vagus nerve aid the motility of food through the intestines, and this is one reason why the vagus nerve is strongly connected with the symptoms manifested in a patient with irritable bowel syndrome. The gut microbiome is also located in here in the intestine (3).

Speaking of the gut-brain axis, "Your digestive system and brain are essentially connected physically and chemically in your body. Inside your gut, you have microbiota, which is a community of about 1,000 types of bacteria. Some of the bacteria are healthy and help us fight disease and improve our gut health, while other bacteria can be harmful, fostering disease and unhealthy cravings" (3).

Digestion Issues Commonly Associated With The Vagus Nerve

The following are the pathologies of the digestive system commonly associated with the vagus nerve:

  1. Irritable bowel syndrome, IBS
  2. Gastroesophageal reflux disease, GERD,
  3. Inflammatory bowel disease
  4. Small intestine bacteria overgrowth (SIBO) (3).

How The Vagus Nerve Is Related To Irritable Bowel Syndrome

Numerous signals are sent from the digestive system and other organs to the brain via the vagus nerve. Additionally, this nerve controls vasomotor activity, some reflex behaviors, including coughing, sneezing, swallowing, and vomiting, as well as internal organ processes including digestion, heart rate, and respiration rate.

Therefore, it is not surprising that irritable bowel syndrome, IBS and small intestine bacteria overgrowth, SIBO are linked to dysfunctional vagus nerves. Remember that stress is one of the main causes of IBS attacks (5).

Constipation, diarrhea, or both are common symptoms of irritable bowel syndrome (IBS), which is also characterized by stomach pain or discomfort. IBS discomfort is thought to be primarily caused by visceral (gut) hypersensitivity, which may also be a role in the development of symptoms including bloating and urgent bowel movements. Visceral hypersensitivity's root cause, however, is not yet identified (4).

Normal homeostasis and gastrointestinal processes depend on the intricate connections between the gut and the central nervous system. The brain-gut axis is a carefully calibrated mechanism that enables bidirectional communication between the brain and the gut (BGA). Movements, reflexes, and sensory impressions in the stomach are controlled by the BGA.

Patients with irritable bowel syndrome, IBS may have altered gut sensations and bidirectional neurotransmission, which can lead to clinical symptoms like discomfort, abnormal gut motility, and even psychological dysfunction like worry and sadness. The pathophysiology of IBS may be significantly influenced by changes in the bidirectional transmission between the brain and the stomach (4).

Numerous symptoms can be caused by vagus nerve dysfunction, which occurs when the vagus nerve is either hyperactive or underactive. For instance, a vagus nerve that isn't working properly might cause delayed stomach emptying (gastroparesis).

Because the vagus nerve, which is responsible for controlling peristalsis (the involuntary contraction and relaxation of the intestine's muscles), is damaged, gut motility will be affected. An unusually low heart rate (bradycardia), a brief loss of consciousness (syncope), and several other symptoms can occur when the vagus nerve is overactive (4).

Stress reduction, heart rate reduction, anxiety reduction, and depression reduction are all benefits of healthy vagus nerve functioning. Better mood and stronger stress resistance are linked to higher vagal tone (health and vitality). Contrarily, heart rate, blood pressure, stress reaction, cognitive impairment, and poor digestion are all linked to vagus nerve dysfunction or a low vagal tone. Since the vagus nerve is involved in practically every disorder that causes hyperarousal, it is not unexpected that it has been linked to irritable bowel syndrome, IBS (4).

Vagus nerve health and activity affect gastrointestinal peristalsis, satisfaction from meals, brain health, inflammation, and a range of other essential bodily processes since it interfaces with the parasympathetic nervous system. One of the most typical signs of vagus nerve dysfunction is pain (as well as a common symptom of IBS). Damage to or malfunction of the vagus nerve can prevent swallowing and affect the normal gag reflex. Damage to the nerve also affects the voice since it regulates some of the throat muscles (4).

Furthermore, studies indicate that IBS patients have high plasma levels of adrenaline and low parasympathetic tones. High levels of stress or panic frequently result in elevated levels of epinephrine, which signal the activation of the "adrenaline rush" or "fight or flight" response. As a result, this discovery raises more evidence for a link between stress, vagus nerve tone, and IBS. This further suggests that maintaining the health of the vagal nerve is vital to treat IBS symptoms (5).

How Is Vagal Tone Important In The Management Of Irritable Bowel Syndrome, IBS?

Your quest for an IBS cure may experience difficulties due to poor vagal tone. Due to the interconnectedness of the diaphragm, IBS, and vagal nerve tone, these can include modifications in motility (the movement of our stomach), adverse effects on the microbiota, and increased gut inflammation. Your body's "rest and digest" mode is activated by raising your vagal tone, and having a higher vagal tone makes it easier for your body to unwind after stress (5).

The vagal nerve tone can be raised over time with continued use, which will result in the body developing a more effective stress response. By relaxing your body and engaging your diaphragm, deep breathing is one way to activate your vagal nerve tone.

Deep breathing also strengthens your diaphragm and vagal nerve tone. According to studies, IBS patients frequently have weak vagal tones because of their link to the diaphragm and poor vagal nerve tone. To people with IBS, where it is probable that diaphragm dysfunction is happening, this emphasizes the need of maintaining healthy vagal nerve tone (5).

Other methods of improving the vagal tone include Yoga and meditation, cold water therapy, singing, and chanting (7).

Gut-Directed Hypnotherapy And The Vagus Nerve In The Management Of IBS

Many IBS sufferers are locked in a cycle whereby anxiety and stress promote IBS symptoms and vice versa. And you keep going around in a loop that never ends. However, gut-directed hypnotherapy can be used to aid in breaking the IBS/anxiety cycle.

A gut-directed hypnotherapy practice involves more than merely closing your eyes for a brief period of relaxation. Instead, it's a powerful method for unwinding and deliberately activating your parasympathetic nervous system through the vagus nerve.

A neurotransmitter called acetylcholine may be released as a result of this stimulation of your vagus nerve, which among other things can reduce your heart rate and soothe your stress response while also providing your body with much-needed rest.

Many patients claim that gut-directed hypnotherapy results in general feelings of wellness and the capacity to sleep better following a session, which is another side effect (the good kind!) (6).

It's crucial to regularly activate your vagus nerve if you experience digestive symptoms like flatulence, bloating, constipation, diarrhea, or acid reflux that are related to irritable bowel syndrome IBS, inflammatory bowel disease (IBD), small intestinal bacterial overgrowth (SIBO), or gastroesophageal reflux disease (GERD) (7).


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