Irritable bowel syndrome: when the gut reacts sensitively
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 Western industrialised countries are affected, with women more frequently than men. Characteristic features include recurring complaints such as abdominal pain, bloating and cramps, as well as altered bowel habits – without any organic cause being identifiable.
The diagnosis is made by the doctor after ruling out other conditions, such as inflammatory bowel disease, coeliac disease or food intolerances. Several factors play a role in treatment: stress management, exercise, medication where appropriate – and, not least, nutrition.
Why nutrition matters so much in IBS
Many of those affected report that certain foods or drinks trigger or worsen their symptoms. In people with IBS, the gut often reacts more sensitively to distension, gases or specific ingredients. This is where nutritional medicine comes in: a tailored IBS diet can help to identify triggers and ease the burden on the gut.
It is important to note: there is no single "IBS diet" that suits everyone. Triggers vary from person to person. What helps one person may have no effect on another. For this reason, nutritional therapy support is often advisable, ideally provided by a qualified dietitian.
Common trigger foods at a glance
Certain foods and ingredients can contribute to symptoms in a sensitive gut. These often include:
- Foods that cause bloating: pulses, brassica vegetables, onions, garlic
- Products high in sugar or sweeteners: in particular sugar alcohols such as sorbitol, mannitol or xylitol (e.g. in sugar-free chewing gum)
- High-fat and fried foods: these can slow digestion
- Coffee, black tea and alcohol: can irritate the intestinal lining
- Carbonated drinks
- Hot spices
- Larger amounts of lactose or fructose where an intolerance is also present
A food and symptom diary kept for two to four weeks can help identify personal triggers. Note what was eaten, in what quantity, and which symptoms occurred and when.
The low-FODMAP diet: a scientifically studied approach
One of the best-studied nutritional strategies for IBS is the low-FODMAP diet. FODMAP stands for Fermentable Oligo-, Di-, Monosaccharides And Polyols – fermentable carbohydrates that are poorly absorbed in the small intestine. In the large intestine they are fermented by bacteria, which can lead to gas formation, water influx and consequently bloating, pain or changes in bowel habits.
Studies suggest that a consistently implemented low-FODMAP diet can contribute to a marked easing of symptoms in some people with IBS.
The three phases of the low-FODMAP diet
The low-FODMAP approach is usually implemented in three sequential phases:
1. Elimination phase (approx. 4–6 weeks): FODMAP-rich foods are largely avoided to see whether symptoms improve.
2. Reintroduction phase: Individual FODMAP groups are gradually tested again to identify personal tolerance thresholds.
3. Long-term diet: Only those foods that are individually poorly tolerated remain restricted. The aim is to maintain a diet that is as varied and balanced as possible.
Examples of FODMAP-rich and FODMAP-low foods
Tend to be high in FODMAPs:
- Wheat, rye, barley in larger amounts
- Apples, pears, mango, watermelon, stone fruit
- Onions, garlic, leeks, artichokes
- Pulses
- Milk, yoghurt, soft cheese (containing lactose)
- Honey, agave syrup, polyol-based sweeteners
Tend to be low in FODMAPs:
- Rice, oats, quinoa, maize
- Carrots, courgettes, cucumbers, spinach, peppers
- Bananas (not overripe), strawberries, blueberries, kiwi, oranges
- Lactose-free dairy products, hard cheese
- Eggs, fish, lean meat
- Tofu, small amounts of nuts
Important: the low-FODMAP diet is not intended as a long-term diet. If implemented too strictly for too long, it can impair the diversity of gut bacteria and lead to nutrient deficiencies. Professional support is therefore expressly recommended.
Further nutritional recommendations for digestive complaints
Independent of the FODMAP concept, there are general tips that can be helpful for digestive complaints:
- Regular, smaller meals rather than fewer large main meals
- Eating slowly and chewing thoroughly – this eases the digestive tract
- Drink enough, particularly still water and unsweetened teas (e.g. peppermint, fennel or chamomile tea)
- Soluble fibre such as psyllium husk or oat bran may offer support in constipation-predominant IBS; insoluble fibre (e.g. wheat bran) is often less well tolerated
- Probiotics: Individual bacterial strains show indications of possible symptom relief in studies; however, the evidence is mixed
- Reduce stress and ensure adequate sleep – the gut-brain axis plays a central role in IBS
What those affected should keep in mind day to day
Changing one's diet requires patience. Many people experience fluctuations in symptom intensity – phases with fewer complaints alternate with more symptomatic episodes. The following points can make everyday life easier:
- Realistic expectations: complete freedom from symptoms is not always achievable, but a noticeable easing is often possible.
- Involve your social environment: informing family, friends or colleagues about dietary changes makes restaurant visits and invitations easier.
- Be prepared: home-cooked meals and snacks taken along provide security when out and about.
- No self-diagnosis: symptoms such as persistent abdominal pain, blood in the stool, unintended weight loss or night-time complaints must be assessed by a doctor.
When medical support is advisable
Anyone who suspects they may have IBS should first seek medical assessment to rule out other conditions. Once the diagnosis is confirmed, nutritional counselling can help find an individually suitable path – whether through an adapted IBS diet, the low-FODMAP diet or other strategies. The combination of nutrition, exercise, stress management and, where appropriate, drug therapy often produces the best results.
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This article does not replace medical advice.