IBS Updates 2022

April is Irritable Bowel Syndrome (IBS) Awareness Month. IBS is one of the most common gastrointestinal conditions in the world. It affects as many as 20% of Canadians so it’s likely that you know at least one person with this functional disorder. IBS can be debilitating, and it presents with symptoms of abdominal pain, bloating, constipation, and/or diarrhea. Despite the prevalence of IBS, we still do not know its exact cause and there is no cure, even though theories abound. Research continues to help us better understand this condition and develop more treatments to manage it.

Bloating

Bloating is a sense of gassiness and internal pressure. You might hear bloating used interchangeably with abdominal distention, but this is a separate disorder with a different physiological process. Abdominal distention occurs when there is a measurable and visible increase in the size of your abdomen. It is normal to have changes in the size of your abdomen throughout the day, but it is significantly greater among people with IBS. It is also possible to have both bloating and abdominal distention, and this occurs among those living with IBS too. You might even feel like the blueberry girl from Willy Wonka & the Chocolate Factory.

Studies show1 that bloating is present in 66-90% of individuals with IBS, significantly affecting more women than men. It is also more common among those with IBS where the predominant symptom is constipation (IBS-C) than those with diarrhea-predominant IBS (IBS-D).

We still do not fully understand the mechanics of bloating and abdominal distention. These physiological processes are complex and consist of interactions between the gut microbiome, intestinal gas production and composition, bowel transit time, and sensory functions in the gastrointestinal (GI) tract. Fortunately, bloating on its own is usually not a harmful condition; however, physicians conduct evaluations to make sure that it is not a symptom of another disease or disorder. Management of bloating and abdominal distention includes a combination of diet, exercise, posture correction, over-the-counter treatments (e.g., probiotics), and prescription medications.

How Gas Travels in Our Body

We accumulate gas in several ways, such as swallowing air, the diffusion of oxygen in our bloodstream, and gas-producing chemical reactions within the GI tract.1 The five most common gases in our GI tract are carbon dioxide (CO2), hydrogen (H2), methane (CH4), nitrogen (N2), and oxygen (O2). A healthy individual could pass gas 14-18 times per day, with a total volume ranging from 214 mL (low fibre diet) to 705 mL (high fibre diet).

IBS and Anxiety

An international team of researchers from 40 institutions across the globe2 discovered that IBS and anxiety share the same genetic pathways and develop independently of each other, instead of one condition causing the other, clarifying previous assumptions that one might have caused the other.

The research team sought to identify genetic susceptibility and risk factors for IBS. To do this, they used the databases of the UK Biobank and the international Bellygenes initiative to conduct a genome-wide analysis on an IBS cohort of 53,400 individuals and 433,201 healthy participants for controls. They found several genetic positions (loci) of interest and replicated these in an independent panel using de-identified data from 23andMe customers who agreed to participate in the study.

They discovered that IBS has overlapping genetic routes with anxiety, depression, neurosis, and schizophrenia. These conditions also share considerable genetic correlations with each other. The genes communicate with the brain through the central nervous system, providing further insight into the brain-gut interactions of IBS.

These findings could explain why psychological symptoms affect as many as 60% of those living with IBS.3 The study authors also believe that their findings offer a strong foundation for future research on therapies that target the nervous system as well as additional support on the use of psychoactive medicines and behavioural therapies for IBS.2

IBS Symptoms in Other GI Conditions

IBS shares a few similar symptoms with celiac disease, inflammatory bowel disease (Crohn’s disease and ulcerative colitis), and colorectal cancer. The IBS diagnostic process already includes investigative testing of these conditions to rule them out. However, there are other GI diseases and disorders that also present IBS-like symptoms, which physicians and specialists also consider.

A systematic review and meta-analysis recently done in the UK4 found that a portion of individuals referred to specialist care for IBS had other GI conditions, such as bile acid diarrhea, carbohydrate malabsorption (mostly lactose and fructose), microscopic colitis, pancreatic exocrine insufficiency, and small intestinal bacterial overgrowth (SIBO). Based on an English literature search on each of these disorders from the publication years of 1978 to 2020, they traced these disorders among patients using recognized diagnostic tests. They found that these conditions were largely present in individuals with IBS-like symptoms compared to healthy controls. However, their research had limitations since it included different types of studies with varying sample sizes and some of the diagnostic tests conducted at the time of its publication lacked accuracy. Still, this may be one of the reasons why treatments are not effective for some individuals with an IBS diagnosis. Future studies should look to examining how often this occurs in practice so that those with IBS symptoms get an early diagnosis and appropriate care.

New Treatments

In our 2018 IBS Global Impact Report,5 we highlighted that those living with IBS continue to struggle with finding effective therapies to help control their symptoms.

Health Canada has approved a prescription medication for adults living with IBS-C. Plecanatide (TrulanceTM), a once-daily oral tablet, is a guanylate cyclase-C (GC-C) agonist that mimics the effects of natural hormones in the body to increase fluid secretion and decrease intestinal transit time, resulting in less abdominal pain.6

Side effects might include diarrhea, nausea, headache, dizziness, cold-like symptoms (nasopharyngitis), and infections in the urinary tract and upper respiratory tract. Health Canada does not recommend TrulanceTM for those with intestinal obstruction.

You can take this medication with or without food, but it may be best to do it without, as some individuals who consumed TrulanceTM with food experienced looser stools and increased abdominal cramping. Also, if you are experiencing nausea, vomiting, diarrhea, and other GI side effects, make sure to avoid high-fat and high-calorie meals before or after you take this medication. Alternatively, you can crush the pills into a powder and mix it in a teaspoon of applesauce or in 30 mL of water. Administration via a nasogastric or gastric feeding tube is another option.

If you miss a dose, skip it, and wait till the next day to take your next tablet. Do not take two doses at the same time if you miss a dose. Store the product in a dry area at room temperature and do not remove the desiccant from the bottle.

TrulanceTM works similarly to linaclotide (Constella®), as they are both GC-C agonists. You can learn more about Constella® by reading our product review at badgut.org.

This medication has not been added to any public formularies yet, but coverage is likely available through private health insurance plans.

Outlook

Studies continue to uncover insights about IBS, the gut microbiome, and potential areas of therapeutic interventions. In 2003, we were the leader in urging the federal government declare April as IBS Awareness Month. We remain dedicated to promoting evidence-based research and supporting appropriate access to care for individuals living with IBS.


First published in the Inside Tract® newsletter issue 221 – 2022
Note: Neither the GI Society nor the CSIR have received remuneration for this article from the companies or affiliates that make the products mentioned.
1. Lacy BE et al. Pathophysiology, Evaluation, and Treatment of Bloating: Hope, Hype, or Hot Air? Gastroenterology and Hepatology. 2011;7(11):729-739.
2. Eijsbouts C et al. Genome-wide analysis of 53,400 people with irritable bowel syndrome highlights shared genetic pathways with mood and anxiety disorders. Nat Genet. 2021;53(11):1543-1552.
3. Weaver KR et al. Irritable Bowel Syndrome: An evidence-based review of new diagnostic criteria and treatment recommendations. AJN. 2017;117(6):48-55.
4. Poon D et al. A systematic review and meta-analysis on the prevalence of non-malignant, organic gastrointestinal disorders misdiagnosed as irritable bowel syndrome. Sci Rep. 2022;12:1949.
5. Gastrointestinal Society. IBS Global Impact Report 2018. Available at: https://badgut.org/ibs-global-impact-report-2018/. Accessed 2022-02-15.
6. Product Monograph Including Patient Medication Information TrulanceTM. Health Canada. 2021. Available at: https://www.canada.ca/en/health-canada/services/drugs-health-products/drug-products/drug-product-database.html. Accessed 2022-02-15.
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