Irritable bowel syndrome: when the gut keeps rebelling
Irritable bowel syndrome (IBS) is one of the most common functional disorders of the gastrointestinal tract. Estimates suggest that around 10 to 15 per cent of the population in Austria are affected, with women somewhat more frequently than men. Characteristic features include recurrent abdominal pain, bloating, diarrhoea, constipation or a combination of both – without any organic cause being detectable.
Many of those affected report that certain foods worsen their symptoms. In fact, diet has become a central element of IBS treatment. This article provides an overview of nutritional approaches, explains the concept of the low-FODMAP diet and shows when medical assessment is advisable.
What is irritable bowel syndrome?
IBS is a disorder of the so-called gut–brain axis. The bowel reacts more sensitively to normal stimuli, motility patterns are altered, and the microbiome – the totality of bacteria living in the gut – may also play a role.
Typical symptoms include:
- Abdominal pain or cramps, often associated with bowel movements
- Bloating and a feeling of distension
- Diarrhoea, constipation or alternating between the two
- Mucus in the stool
- A feeling of incomplete bowel emptying
Symptoms persist for at least three months and noticeably affect quality of life. Before an IBS diagnosis is made, other conditions such as inflammatory bowel disease, coeliac disease or food intolerances must be ruled out.
Why diet matters so much in IBS
Diet directly influences how the bowel behaves: some foods are poorly absorbed in the small intestine, are fermented by bacteria in the large intestine and can generate gases and osmotically active substances there. In a hypersensitive bowel, this is often enough to trigger the typical complaints.
An adapted IBS diet can help to ease symptoms, identify individual triggers and improve quality of life. It is important to note that there is no one-size-fits-all diet. Instead, the goal is to individualise eating habits step by step.
General dietary tips for IBS
Before strict diets are considered, it is worth implementing some basic principles. These so-called "first-line recommendations" are anchored in international guidelines:
- Regular, calm meals in a relaxed setting
- Chew well and eat slowly
- Avoid heavy, very fatty meals
- Ensure adequate fluid intake, particularly still water and unsweetened teas
- Limit coffee, alcohol and hot spices to moderate amounts
- Observe strongly gas-producing foods such as pulses, onions or cabbage
- Reduce sugar substitutes such as sorbitol or xylitol
A food and symptom diary kept over two to four weeks can also help to reveal possible triggers.
Low FODMAP: a well-researched approach
If general measures are not enough, the low-FODMAP diet often comes into play. FODMAP stands for "Fermentable Oligo-, Di-, Monosaccharides And Polyols" – certain carbohydrates and sugar alcohols that are poorly absorbed in the small intestine.
These include, among others:
- Fructose in honey, apples, pears or mango
- Lactose in milk and many dairy products
- Fructans in wheat, rye, onions and garlic
- Galactans in pulses such as lentils or chickpeas
- Polyols such as sorbitol or mannitol, found, for example, in stone fruit and sugar-free chewing gum
Studies show that a low-FODMAP diet can significantly reduce symptoms in many people with IBS. However, it is not intended as a permanent way of eating, but is implemented in three phases:
1. Elimination phase
Over around four to six weeks, FODMAP-rich foods are largely avoided. The aim is to calm symptoms.
2. Reintroduction phase
Individual FODMAP groups are gradually tested in order to determine personal tolerance thresholds. This phase often lasts six to eight weeks.
3. Long-term phase
Based on the findings, a varied, sustainable diet is developed that only restricts those FODMAPs that actually trigger symptoms.
Because the strict elimination phase can be nutritionally challenging, it should ideally be supervised by a qualified dietitian or a doctor with experience in nutritional medicine.
Fibre, probiotics and other building blocks
Beyond FODMAPs, other dietary factors play a role:
- Soluble fibre such as psyllium husk can be helpful in constipation and, in some cases, in diarrhoea.
- Insoluble fibre from wholegrain products can worsen symptoms in some people and should be dosed individually.
- Probiotics – preparations containing live bacterial cultures – may contribute to symptom relief in a proportion of those affected. Which strain is suitable varies from person to person.
- Peppermint oil in enteric-coated capsules has shown antispasmodic effects in studies and can be used as a supplementary measure.
When medical assessment is advisable
Not every abdominal complaint is IBS. Medical assessment is particularly advisable in the case of:
- Symptoms appearing for the first time after the age of 50
- Unintentional weight loss
- Blood in the stool or persistently dark stools
- Night-time symptoms that disturb sleep
- Persistent fever or exhaustion
- IBS-like symptoms in relatives with bowel disease or bowel cancer
In these cases, organic causes should be ruled out before an IBS diagnosis is made and dietary therapy is started. Possible coeliac disease, lactose or fructose intolerance can also be clarified through appropriate testing.
Conclusion: individual, patient and well supported
Diet is an important lever in managing IBS – but it is not a cure-all. General measures, a structured low-FODMAP diet and targeted complementary elements such as soluble fibre or probiotics can significantly reduce symptoms in many of those affected. The key is an individual, step-by-step approach, ideally supervised by a doctor and a dietitian.
Anyone who suspects they may have IBS should first seek a thorough medical assessment. This allows other conditions to be ruled out and a targeted, practical dietary strategy to be developed.
This article does not replace medical advice.