IBS with mixed bowel habit (IBS-M) was the most common subtype with the Rome III criteria (about 34%), but IBS with diarrhoea (IBS-D) was the most common subtype with the Rome IV criteria (about 32%). The prevalence of IBS was higher in women than in men (12% vs 8.6%).
Myths vs facts
Myth 1: Come on, IBS is not that big a deal!
Fact: People with IBS frequently report feeling depressed, embarrassed, self-conscious, stigmatised, and adapt their lifestyles accordingly
Due to the often unpredictable and persistent nature of the symptoms, people with IBS make considerable life-limiting changes, and the full impact of the condition is often underestimated. The condition has a negative effect on the quality of relationships and limits participation in routine social activities. Many of those with IBS believe that they are not taken seriously, and a diagnosis of IBS can leave them feeling stigmatised. Some who have IBS may be discouraged from seeking medical help because they believe that they will not be heard by the healthcare professionals, and the absence of effective support may further contribute to feelings of social isolation.
Myth 2: IBS is a psychological disorder. It is all in your head!
Fact: IBS is the most recognised disorder of the gut-brain interaction
IBS is defined as an abnormal condition of gut contractions (motility) and increased gut sensations (visceral hypersensitivity). Although the underlying cause of IBS is still unclear, in recent years increasing evidence has emerged that it is a disorder caused by altered brain-gut interaction. Brain networks involved in central processing and modulation of IBS-related visceral pain include the salience, sensorimotor, default mode, emotional arousal, central executive, and central autonomic networks. Evidence shows that dynamic interactions between brain networks are altered in IBS.
It has also been postulated that IBS may also be caused by:
- Altered GI motility (changes in the way waste moves through the gut)
- Visceral hypersensitivity (increased sensitivity of nerves within the gut)
- Post-infectious reactivity: (IBS that occurs after a gut infection eg gastroenteritis)
- Alteration in faecal microflora/bacterial overgrowth (changes to microorganisms in the body)
- Food sensitivities/carbohydrate malabsorption (the inability to eat certain foods)
- Intestinal inflammation.
While stress, anxiety, and depression can increase symptom burden, they do not cause IBS. This myth is one of the most dangerous, leading to stigmatisation of patients with the condition.
On average, it takes four years for individuals with IBS to receive a definitive diagnosis. As there are no diagnostic disease markers for IBS, guidelines recommend clinicians make a positive diagnosis using criteria that are based on the person’s symptoms (see box 1).
Myth 3: Everyone with IBS experiences the same symptoms
Fact: Everyone with IBS has a unique experience
There are four main subtypes: IBS with prominent diarrhoea (IBS-D), IBS with constipation (IBS-C), IBS with mixed symptoms of both constipation and diarrhoea (IBS-M) and IBS-undetermined (IBS-U). There are also variations in the intensity of other symptoms associated with IBS such as nausea, flatulence, back pain, fatigue, or bowel incontinence.
Myth 4: Incorporating dietary fibre will improve symptoms
Fact: Not all dietary fibres are effective
Dietary fibre is frequently recommended to improve symptoms in patients with IBS – particularly when constipation is the predominant complaint. But according to the 2021 American College of Gastroenterology (ACG) guideline for the management of IBS, not all fibres are effective. In general, different types of fibre can be distinguished based on their solubility, viscosity, and ability to resist fermentation in the colon. Soluble fibre is found in psyllium, oat bran, barley, and beans. Insoluble fibre is found in wheat bran, whole grains, and some vegetables. Fibres that exert laxative effects tend to increase stool water content and resist colonic fermentation. Conversely, fibres that ferment in the colon will lose their water-holding capacity and produce gas that could aggravate symptoms of bloating and flatulence. The guidelines recommend the use of soluble fibre.
Myth 5: The FODSMAP diet should be recommended for all patients with IBS
Fact: Although the current evidence is supportive, many questions about the low FODMAP diet remain unanswered
There is a need for high-quality long-term data on the efficacy, safety of the FODSMAP diet including any unintended effects on the gut microbiota. Data are also needed on the consequences of non-adherence to the diet. The ACG does, however, recommend a limited trial of a low FODMAP diet in patients with IBS to improve global symptoms. The authors stress that the services of a professionally trained GI dietician is required to supervise patients on trials.
Myth 6: IBS cannot be treated; patients just must learn to live with it
Fact: Although there is no known cure for IBS, there are various approved treatments available to control symptoms, except for IBS-M or IBS-U
The ACG guideline (2021) recommends:
- Chloride channel activators: A dose of 8μg lubiprostone twice daily is recommended to relieve global and individual symptoms in patients with IBS-C. Although there may be a delay in initial response, improvement in global symptoms is maintained or increases over time. Lubiprostone exhibits an appropriate safety profile with the most common adverse event (AE) being GI in nature. Nausea is dose-dependent but may be reduced by consuming lubiprostone with meals.
- Guanylate cyclase activators: once-daily linaclotide (290μg) and plecanatide (3mg) seem effective for relieving overall and individual symptoms of IBS-C. Responses develop quickly and are maintained over time. Diarrhoea is the most common AE experienced, but discontinuation rates due to diarrhoea are low and both are well-tolerated.
- Peppermint oil: has been well-tolerated in the available trials. That said, only a small number of commercially available peppermint oil supplements have undergone rigorous testing of efficacy and safety.
- 5-HT4 agonist tegaserod: This can be used to treat IBS-C symptoms in women <65 years with ≤1 cardiovascular (CV) risk factors who have not adequately responded to secretagogues. Tegaserod is the only approved 5-HT4 receptor agonist for the treatment of adult women <65 years with IBS-C. It is contraindicated in patients with more than one CV risk factors.
- Rifaximin: an effective, safe treatment choice for patients with IBS-D symptoms.
- Alosetron: current evidence supports using alosetron to relieve global symptoms in women with severe IBS-D when other interventions have failed. Within a small therapeutic window (0.5m–1mg orally), it seems safe and with low risk of the development of severe constipation or ischaemic colitis.
- Mixed opioid agonists/antagonists: eluxadoline improves global IBS-D symptoms in men and women. A randomised, prospective study and a retrospective analysis have also shown that eluxadoline improves symptoms in patients with IBS-D who have failed previous trials of loperamide. Loperamide is not recommended as first-line therapy for treating IBS-D symptoms because it may improve diarrhoea but not improve global IBS symptoms. Eluxadoline is contraindicated in some patients because of concerns over pancreatitis and sphincter of Oddi dysfunction.
- Tricyclic antidepressants (TCAs): may improve global IBS symptoms. Data from large head-to-head trials comparing different TCAs for the treatment of patients with IBS are not available to provide recommendations on a specific TCA. The ACG recommends that clinicians become familiar with the different types of TCAs to appreciate the differences in efficacy and adverse effects. Patients should be started on a low dose (eg 10mg amitriptyline or 10mg of desipramine) with gradual dose titration upward to achieve therapeutic relief of symptoms while minimising side effects. Anecdotally, patients with IBS-D may respond better because of the anticholinergic properties of TCAs, which may improve symptoms of urgency and diarrhoea. However, caution should be directed toward potential side effects including dry mouth, dry eyes, urinary retention, constipation and cardiac arrhythmias.
- Gut-directed psychotherapies (GDPs): the use of GDPs in conjunction with other IBS therapies for patients who are emotionally stable but who exhibit cognitive-affective drivers of IBS symptoms. GDPs are IBS-subtype agnostic and can address the large group of patients with IBS-M or IBS-U for whom fewer pharmacological treatments are available.
Box 1: ACG diagnostic recommendations
To accurately categorise a patient with IBS by subtype, the ACG recommends the following:
- Predominant stool consistency can be determined based on the Bristol Stool Form Scale (BSFS).
- Determine patient's primary stool consistency only on the days s/he reports abnormal bowel movements. This determination should be made when patient is off therapy(ies) that could affect bowel pattern. Daily diaries should be performed for two weeks for the most accurate assessment.
- Once the pattern of stool consistency is determined, subtype decisions can be made according to the Rome IV criteria:
- IBS-C: >25% of bowel movements associated with BSFS 1 or 2 with BSFS 6 or 7 occurring less than 25%
- IBS-D: >25% of bowel movements associated with BSFS 6 or 7 with less than 25% of bowel movements with BSFS 1 or 2
- IBS-M: >25% of bowel movements associated with BSFS 1 or 2 and >25% of bowel movements associated with BSFS 6 or 7
- IBS-U: cannot be determined.
Box 2: Is a colonoscopy recommended for all patients with IBS?
According to the authors of the ACG guidelines current evidence does not support routine colonoscopy in patients with IBS <45 years in the absence of alarm features. In patients >45 years, a recent negative colonoscopy for colon cancer screening or for other investigative purposes, should mitigate the need for another colonoscopy for IBS symptoms in the absence of new alarm features. In patients considered to be at high risk of microscopic colitis (older age [>60], female gender, and more intense diarrhoea), there may be mounting evidence to support the use of colonoscopy.
- Bhatt RV, Gupta A, Labus JS, et al. A neuropsychosocial signature predicts longitudinal symptom changes in women with irritable bowel syndrome. Nature Molecular Psychiatry, 2021.
- Canadian Society of Intestinal Research. 7 Irritable Bowel Syndrome Myths
- Lacy BE and Patel NK. Rome Criteria and a Diagnostic Approach to Irritable Bowel Syndrome. J Clin Med, 2017.
- Lacy BE, Pimentel M, Brenner DM, et al. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. The American Journal of Gastroenterology, 2021.
- Oka P, Parr H, Barberio B, et al. Global prevalence of irritable bowel syndrome according to Rome III or IV criteria: a systematic review and meta-analysis. The Lancet Gastroenterology and Hepatology, 2020.
- Smith J. Busting 7 IBS Myths for IBS Awareness Month. https://www.mindsethealth.com/matter/ibs-awareness-month