Irritable bowel syndrome (IBS) is a common disorder that affects the gastrointestinal tract, characterized by abdominal discomforts associated with altered bowel movements, and is currently diagnosed according to the new Rome IV criteria. Symptoms linked to the hypersensitivity of the nerves are found in the gut lining, and these nerves communicate with the brain to process the information. There are typically four main types of IBS, and these include,

  • IBS-D symptoms include diarrhoea and stomach discomfort.
  • IBD-C – mostly constipation and abdominal discomfort
  • IBS-M – alternating loose and constipated stools with abdominal discomfort
  • IBS-U – undefined sub-types and symptoms vary

Researchers categorize IBS based on how the stools look on the days when there are symptoms or flare-ups. Usually, people with IBS have normal bowels on certain days and abnormal bowels on certain other days. The abnormal days identify the type of IBS, which can be constipation, diarrhoea, mixed stool, or unidentified.

Usual symptoms of IBS include;

  • Abdominal pain and cramps, generally accompanied by a need to urinate.
  • Excess gas and bloating.
  • Constipation, diarrhea or a mix of both or alternating between the two.
  • Mucus in the faeces (may appear white).
  • Feeling like unable to empty the bowels after pooping.
  • Evacuation is urgent, or there is a sense of incompleteness.

Individuals with IBS experience symptoms that could be not related to the intestine at all and these include headaches, migraines, anxiety, depression, and so on. Some people can tolerate these symptoms but others may not be able to and it affects the quality of their life with their day-to-day activities. Stress is often associated with the onset of symptoms, and the symptoms reduce when the stress is gone.

Researchers classify IBS as a neuro-gastrointestinal disorder, with communication challenges between the gut and the brain.

  • Dysmotility – These lead to dysmotility, that is, problems with gastrointestinal muscles to contract and move food through the gut. If the abdominal contractions are stronger and last longer periods of time, then it can lead to flatulence, bloating, and diarrhea. When there is weak contractions, then it can slow the food passage and lead to dry and hard stools.
  • Chronic infections – After a chronic bacterial or viral infection, IBS can develop leading to diarrhea.
  • Stress – excessive stress, be it financial, official, family, or stress since childhood for a prolonged period of time can cause IBS.
  • Visceral hypersensitivity – that is having extra-sensitive nerves in the gastrointestinal tract, lower pain tolerance, and super sensitive to abdominal pain or discomfort.
  • Imbalance in gut microbes – changes in the microbial balance, that is bacteria, fungi, and viruses which typically reside in the intestines and play a key role in gut health.

The enteric nervous system (ENS) denotes the nerves in the intestinal wall that control the way the gut responds to the food we eat. These nerves play an important role in the digestion, absorption, and elimination of wastes. When a person has IBS, then that person experiences symptoms such as bloating, acidity, abdominal pain, constipation, diarrhea, etc, all of which are the reactions sent by the enteric nervous system. The enteric nervous system can sense invasive organisms like bacteria and viruses and creates a protective environment by causing diarrhea, bloating, etc. Thus when someone is having gastrointestinal illnesses with inflammation, then activities like sensitivity, motility, and secretion are altered, and the individuals suffer from a range of symptoms.

Also, as the nerves in the gut are controlled by the brain, this is called the gut-brain axis communication. This pathway is bi-directional in nature, that is, communicating between the brain and digestive tract in a to and fro pathway. The gut-brain axis involves communication between several systems in the body including the nervous system in breathing, thinking, remembering, and feeling emotions, the endocrine system in regulating all the biological processes in the body, and the immune system in protecting the body from diseases.

When there is an imbalance in this communication, then normal sensations like food entering the stomach, digestion, absorption, and elimination do not happen appropriately, leading to all the IBS symptoms. However, if there is an imbalance in the gut-brain axis due to stress events (can lead to changes in gut motility and permeability) or early stress and traumatic experiences in life ((lead to more severe and difficult-to-treat gut symptoms)  or anxiety and depression further triggers unnecessary gut symptoms, and visceral hypersensitivity is a tendency to experience discomfort or pain in response to normal bowel functions which makes the enteric nerves to send stronger pain signals to the brain in response to activity within the gastrointestinal tract. Food passing through the digestive system or regular gas patterns are now interpreted as painful or uncomfortable muscle spasms.

Research evidence shows the presence of an imbalance in the microbial population in the gut of an IBS person. This could be due to excessive use of antibiotics which disturbs the gut flora and predispose an individual to IBS, or a sudden IBS episode after a stomach or intestinal infection, and even small intestinal bacterial overgrowth may be associated with IBS.

As a result, a dysfunction in the gut-brain axis and the gut microbiome is seen. Usually, IBS is diagnosed based solely on the presence of specific symptoms and one’s clinical history. A long-term management is needed for the IBS condition and it’s not a one-time fix. Finding the root cause and personalizing the treatment plan which includes better food intake with probiotics, prebiotics which help in improving the gut bacteria and bring a balance in the gut microbiome, and lifestyle modifications such as stress reduction, improved sleep and physical activity, and behavioral therapy can help in the management of IBS.