Irritable bowel syndrome, known as IBS for short, is a gastrointestinal disorder affecting the large intestine. The exact cause of IBS remains unclear, but it is thought to involve abnormal muscle contractions in the colon, heightened pain sensitivity, changes in the gut microbiome, and disrupted communication between the brain and the gut. 1Symptoms of IBS vary but commonly include:2

  • Abdominal pain

  • Cramping

  • Bloating

  • Gas

  • Constipation

  • Diarrhoea

Although the symptoms of IBS often change over time, people tend to develop their own pattern. For example, some people have mostly diarrhoea, some have mostly constipation and others have abdominal pain without a major change in bowel movements. Triggers can differ from person-to-person.

Diagnosis

There is no single test for IBS. It is largely classified as a condition of exclusion. In other words, IBS is usually diagnosed after all other causes of symptoms, such as infection or disease, are ruled out. The Rome Criteria – in its fourth iteration as of 2016 – is a set of defined criteria to more accurately diagnose IBS and other functional gastrointestinal disorders, which involve the brain as well as the gut. The guidelines outline symptoms and apply parameters such as frequency and duration make a possible a more accurate diagnosis of IBS.3

One key characteristic of Akkermansia muciniphila is its ability to live in the mucus, which it does by expressing mucus-degrading enzymes. This means that Akkermansia muciniphila does not rely on dietary substances to feed itself, giving it a competitive advantage over bacteria that rely on fibres and food particles as their main source of nutrition 1.

As a result, Akkermansia muciniphila lives in the mucus layer that covers cells in the intestine. Being located so close to such cells, it is even able to communicate with them. 2

The Rome IV Criteria for IBS are:4

Recurrent abdominal pain on average at least one day per week in the last three months, associated with two or more of the following criteria:*

  • Related to defecation

  • Associated with a change in frequency of stool

  • Associated with a change in form (appearance) of stool

*Criteria fulfilled for the last three months with symptom onset at least six months prior to diagnosis.

Far from being a homogeneous condition, IBS is a spectrum and people can experience different forms of it, including diarrhoea-predominant and constipation-predominant, and alternating between constipation and diarrhoea.5

IBS Subtypes

Predominant bowel habits are based on stool form on days with at least one abnormal bowel movement.*

IBS with predominant constipation (IBS-C):
> ¼ (25%) of bowel movements with Bristol stool types 1 or 2 and < ¼ (25%) of bowel movements with Bristol stool types 6 or 7.
IBS with predominant diarrhoea (IBS-D):
> ¼ (25%) of bowel movements with Bristol stool types 6 or 7 and < ¼ (25%) of bowel movements with Bristol stool types 1 or 2.
IBS with mixed bowel habits (IBS-M):
> ¼ (25%) of bowel movements with Bristol stool types 1 or 2 and > ¼ (25%) of bowel movements with Bristol stool types 6 or 7.
IBS Unclassified (IBS-U):
Patients who meet diagnostic criteria for IBS but whose bowel habits cannot be accurately categorised into one of the three groups above should be categorised as having IBS-U.

Bristol Stool Form Scale

The global prevalence of IBS

  • IBS affects between 5-10% of the world's population. 7

  • Approximately, 2 in every 3 IBS sufferers are female. 7

  • Most people affected by IBS are under the age of 50 although many older adults suffer. 7

  • Approximately 40% of those with IBS have mild symptoms, 35% have moderate IBS, and 25% have severe IBS. 8

IBS and links with stress & anxiety

Stress and anxiety have been found to influence the functioning of the gut-brain axis, a bidirectional communication system between the brain and the gut.9

Psychological stress can trigger physiological changes in the gut, leading to increased sensitivity, altered motility, and abnormal contractions.1   These changes can contribute to the development or exacerbation of IBS symptoms.

A study that looked at more than 1.2 million IBS patient hospitalisations from 4,000 U.S. hospitals over a three-year period, found that over 38% had anxiety, and over 27% had depression. Both figures were double the rate of anxiety and depression found in those without IBS.10

The connection between stress and Irritable Bowel Syndrome (IBS) involves many different factors including the release of stress hormones, gut bacteria and intestinal permeability. Stress and anxiety can disrupt the balance of gut bacteria, impacting gut function and contributing to IBS symptoms.

Stress and anxiety can form a vicious circle, starting with triggers such as a traumatic event or infection, leading to changes in bowel function, resulting in disruptions to daily routines or eating habits. These concerns can grow and start to affect work or social lives and cause further stress and anxiety.11

REFERENCES

  1.  Ford AC, Sperber AD, Corsetti M, Camilleri M. Irritable bowel syndrome. Lancet. 2020 Nov 21;396(10263):1675-1688. doi: 10.1016/S0140-6736(20)31548-8. Epub 2020 Oct 10. PMID: 33049223. 
  2.  Irritable bowel symptoms, https://www.nhs.uk/conditions/irritable-bowel-syndrome-ibs/symptoms/
  3.  Drossman DA. Functional gastrointestinal disorders: history, pathophysiology, clinical features, and Rome IV. Gastroenterology. 2016;150(6):1262-1279. doi:10.1053/j.gastro.2016.02.032
  4.  Rome Foundation. Rome IV Criteria – https://theromefoundation.org/rome-iv/rome-iv-criteria/
  5.  https://www.ncbi.nlm.nih.gov/books/NBK534810/#:~:text=IBS%20typically%20consists%20of%20abdominal,and%20stool%20pattern%20with%20time
  6.  Francis CY, Morris J, Whorwell PJ. The irritable bowel severity scoring system: a simple method of monitoring irritable bowel syndrome and its progress. Aliment Pharmacol Ther. 1997 Apr;11(2):395-402. doi: 10.1046/j.1365-2036.1997.142318000.x. PMID: 9146781.
  7.  IBS Facts and Statistics, https://aboutibs.org/what-is-ibs/facts-about-ibs/
  8.  Drossman DA, Chang L, Bellamy N, et al. Severity in irritable bowel syndrome: a Rome Foundation Working Team report. Am J Gastroenterol. 2011;106(10):1749-1760. doi:10.1038/ajg.2011.201
  9.  The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4367209/
  10.  Tarar ZI, Farooq U, Zafar Y, et al. Burden of anxiety and depression among hospitalized patients with irritable bowel syndrome: a nationwide analysis. Ir J Med Sci. 2023;192(5):2159-2166. doi:10.1007/s11845-022-03258-6
  11.  The Vicious Circle, IBS & Stress – Bladder & Bowel Community, https://www.bladderandbowel.org/news/vicious-circle-ibs-and-stress/