Irritable Bowel Syndrome (IBS) is one of the most common functional gastrointestinal disorders in the Western world, affecting an estimated 10–15% of adults, though many remain undiagnosed and untreated. Women are significantly more likely to be diagnosed than men, and new cases are most common in young adults aged 20–40. The annual incidence is around 1–2 new cases per 100 people, and IBS accounts for a substantial share of GP and specialist visits. Its impact is not just physical — the condition can severely affect quality of life, mental health, and work productivity. In the United States alone, IBS is estimated to cost over $20 billion per year in direct healthcare expenses and indirect costs like absenteeism and presenteeism, making it a major contributor to hidden productivity loss in workplaces.
Over the past century, our relationship with food has shifted dramatically. The modern food system is now dominated by highly refined carbohydrates, ultra-processed ingredients, and pervasive use of preservatives and additives to increase shelf life and maximise profit. Where once our diets were rich in home cooked, whole, seasonal, and minimally processed foods, today many of the staples people consume daily are stripped of fibre and nutrients, then replaced with cheap sugars, emulsifiers, and artificial flavours.
Industrialised agriculture and large-scale farming practices have also led to the widespread use of pesticides and herbicides, such as glyphosate, which can disrupt our gut microbiome and may contribute to low-grade inflammation in sensitive individuals. These profound shifts mean our digestive systems — evolved for diverse, fibre-rich, microbiome-friendly whole foods — are now bombarded by ingredients they were never designed to process in such volumes.
This reality helps explain why conditions like IBS, food intolerances, and functional gut disorders have become so common in the modern world, and reminds us how vital it is to return to a diet that nourishes and protects our gut ecology.
Irritable Bowel Syndrome (IBS) is a common functional gastrointestinal disorder defined by recurrent abdominal discomfort linked to changes in bowel habits, with no identifiable structural or biochemical cause. The diagnosis is clinical, that means that there is no test other than asking about symptoms to help us make this diagnosis. We use the Rome IV criteria to help us to make the right diagnosis. It’s important to rule out “red flags” for more serious diseases like inflammatory bowel diseases or cancers, but when these are absent, IBS can be confidently diagnosed without extensive testing.
To meet the Rome IV criteria for IBS, a patient must have:
- Recurrent abdominal pain, on average, at least 1 day per week in the last 3 months
- Symptom onset at least 6 months before diagnosis
- Abdominal pain associated with two or more of the following:
- Related to defecation (pain improves or worsens when you poop)
- Associated with a change in stool frequency (more or less often than usual)
- Associated with a change in stool form (appearance
Red flags that should be investigated to exclude more sinister causes of gut disease are:
- Unintentional, unexplained weight loss
- Rectal bleeding (blood in stool, black/tarry stools)
- Iron-deficiency anaemia (especially new or worsening)
- Nocturnal symptoms (pain or diarrhoea waking you up from sleep)
- A noticeable and new change in gut symptoms after age 50
- Family history of colorectal cancer, IBD, or celiac disease
- Persistent vomiting (not just nausea)
- Severe or progressively worsening abdominal pain
- Palpable abdominal or rectal mass
- Signs of obstruction (severe bloating, constipation with vomiting)
- Fistulas, abscesses, or perianal disease (suggests IBD)
Colon cancer is a strongly heritable cancer and so individuals with a first degree relative who was diagnosed with colon cancer should be screened 10 years earlier than the age of the diagnosis in their relative. So if your mom was diagnosed at the age of 35, you should start your own screening colonoscopy at 25.
IBS is a tricky disease to treat and can really affect a person’s quality of life. If you fit the criteria listed above, you may benefit greatly from chatting to your doctor and seeing a dietician. Many over the counter remedies can be very supportive including l-glutamine, Iberogast and peppermint oil. A supported elimination diet excluding high FODMAP foods can also be a very helpful tool. In order to avoid unnecessary food restrictions, doing this diet in collaboration with a dietician or expert is best practice.
Eating at consistent times of the day, avoiding constipation, hydrating with water and sticking to a whole food diet low in refined foods and additives is a good step towards cultivating healthy gut function. You can think of your gut as an extension of your brain, so if you have gut symptoms and symptoms of high anxiety or low mood, it’s even more important to address your diet. How we eat can have a very significant impact on our cognitive and mood health.
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