Irritable bowel syndrome is a disorder of gut-brain interactions characterised by abdominal discomfort and distension, and alterations in bowel habits, including diarrhoea, constipation or a combination of both.
It is estimated that it affects 5-10% of the world population and that it has an annual direct healthcare cost between £1.3 and £2 billion in the United Kingdom.
Although not life-threatening, IBS has an enormous influence on quality of life, affecting all aspects of daily activities, from work productivity to social engagements.
Two thirds of individuals diagnosed with IBS happen to be women, perhaps because they are more likely to seek medical assistance than men, or because hormonal fluctuations can contribute to additional symptoms.
Once dubbed as “a disease of neurotic women”, IBS has been considered for decades a condition that originates purely from psychological stress, and although it is known that IBS sufferers are more likely to experience episodes of depression and anxiety, recent research suggests a combination of factors, beyond stress contribute to the development of it - gastrointestinal dysmotility, visceral hypersensitivity, and altered gut microbiota composition are some key factors to take into consideration, as well as a bacterial infection, one of the strongest risk factors for IBS development, affecting up to 10% of individuals that have an episode of gastroenteritis.
Post-infectious IBS is a form of IBS caused by a bacterial, viral or protozoal infection.
Bacteria such as Campylobacter, Salmonella, Shigella, and E.coli, and viruses and parasites such as Norovirus and Giardia have all been associated with the development of PI-IBS.
Foodborne illnesses affect 18 million people in the UK every year, and according to a systematic review and meta-analysis, the risk of developing IBS is 4.2 times higher in individuals exposed to a gastrointestinal infection than in individuals who are not, and women, particularly those with severe gastroenteritis, are at increased risk, as are individuals with psychological distress and antibiotic users.
It is hypothesised that due to the high incidence of stomach bugs and poor recall of milder episodes, the true prevalence of PI-IBS may be underestimated.
Unfortunately the majority of individuals are not educated about the link between GI infections and the development of chronic GI symptoms, being left with little to no help regarding what to do next, while dealing with debilitating symptoms that impact quality of life.
The mechanism between a gastrointestinal infection and IBS is multifactorial, as a stomach bug can disrupt the normal functioning of the gut, leading to long-term changes in gut motility and sensitivity. It can alter gut microbiota composition allowing opportunistic and pro-inflammatory bacteria to proliferate, in addition to promoting gut barrier and immune system dysfunction, all of which can contribute to the development of IBS symptoms.
To a subset of people, PI-IBS can also trigger autoimmunity due to the release of a bacterial toxin called Cytolethal Distending Toxin B, or CdtB for short. Antibodies against CdtB can mistakenly attack Vinculin, a naturally occurring protein in the body that is critical for healthy gut function.
The production of anti-vinculin leads to gut nerve damage and improper functioning of the Migrating Motor Complex (MMC), a series of rhythmic contractions that move through the gastrointestinal tract during periods of fasting, helping to clear out undigested food and bacteria.
Impaired functioning of the MMC will likely result in Small Intestinal Bacterial Overgrowth (SIBO), a condition that shares similar symptoms with IBS, such as persistent bloating, abdominal pain, gas and changes in bowel habits, and can contribute further to suboptimal quality of life as it is often misdiagnosed as IBS and individuals may not get the appropriate treatment for years.
At present PI-IBS, just like any other IBS type, is considered a chronic condition and although some specific strategies have been tested specifically for it, current management recommendations are the same as for all other IBS types. Some strategies are well supported by scientific evidence such as the low FODMAP diet, cognitive behavioural therapy and yoga as well as the restriction of spicy foods, fatty meals and alcohol.
Most recent research suggests that gut microbiota restoration, enhancement of gut barrier function and targeting visceral hypersensitivity remain the most promising areas for therapeutic interventions.
It is evident that a gastrointestinal infection can be a catalyst for the development of IBS and other GI conditions yet there is a surprising lack of communication around it. With 1 in every 9 people developing IBS after catching a stomach bug, it is safe to say that the public should be educated on preventative measures by putting into practice basic strategies such as drinking bottled water where needed, avoiding food that has been left at room temperature for long periods of time, as well as ensuring food hygiene recommendations are followed by establishments when eating out or ordering takeaway food.
Given its notable impact on women, healthcare cost and the long-lasting implications in quality of life, increasing public awareness about the importance of gut health and the risks associated with stomach bugs is paramount.
It is also crucial to continue supporting research into innovative therapeutic interventions that target the complex mechanisms behind IBS development. An international survey with IBS patients found that to receive a treatment that would make them symptom free, patients would be willing to give up 25% of their remaining life (average 15 years), which emphasises how debilitating living with this condition can be.
Marilia Chamon is a renowned gut health specialist and registered nutritional therapist, she is the founder of Gutfulness Nutrition. Marilia has undergone extensive training on the pathophysiology of IBS in addition to completing the Monash University ‘Low FODMAP Diet for IBS’ training course for health professionals. Marilia specialises in gut health as a result of her own health journey, having struggled with unexplained digestive symptoms for nearly a decade, following an episode of food poisoning.