Diet for irritable bowel syndrome: what to try, in order
Change how you eat before you change what you eat: regular meals, a slower pace, less caffeine and fizzy drinks, soluble fibre rather than coarse bran, and regular exercise[2]. If symptoms persist, a low FODMAP trial is the best-evidenced next step[3] — but it runs for two to six weeks and is then reintroduced group by group, never kept indefinitely[4]. Unintended weight loss, bleeding or night-waking symptoms are not IBS and need a doctor[5].
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What IBS is, and what a diet cannot fix
Irritable bowel syndrome is a disorder of how the gut and the nervous system talk to each other. The bowel looks normal under a camera, but it is more sensitive to stretch, it moves food along faster or slower than it should, and the result is the familiar pattern: cramping pain, bloating, wind, and stools that swing between loose and hard. It is common rather than rare — around 4.1% of adults meet the current diagnostic criteria for it[1].
The first thing to settle is that it is IBS at all. Weight you did not mean to lose, blood in the stool, a fever, anaemia, symptoms that wake you at night, a first onset in later life, or a family history of bowel or ovarian cancer are not IBS features and need a doctor rather than a diet[5]. Coeliac disease is worth excluding by blood test too, because it can look identical from the outside. Everything below assumes a diagnosis has already been made.
Start with how you eat, not with what you cut
The reflex is to delete foods. Guidelines put the ordinary habits first, because they help a large share of people and cost nothing in nutrition: eat at regular times instead of one enormous late meal, do not skip meals and then arrive at dinner ravenous, slow the meal down, keep caffeine and alcohol moderate, cut back on fizzy drinks and sugar alcohols in sugar-free gum and sweets, and treat very fatty and heavily spiced dishes as a known trigger worth testing rather than an innocent bystander[2].
Fibre needs care, and the type matters more than the amount. Soluble fibre — ispaghula or psyllium husk — improves overall symptoms and pain and is the one to use, started low at around 3 to 4 grams a day and built up slowly so it does not cause the bloating it is meant to relieve. Coarse insoluble bran is the opposite and often makes IBS worse[2]. Regular exercise is part of the standard advice, not an optional extra[2].
The low FODMAP diet, and what the evidence actually says
FODMAPs are short-chain carbohydrates that the small intestine absorbs poorly: the fructans in wheat, onion and garlic, the galacto-oligosaccharides in beans and lentils, lactose in milk, excess fructose in honey and some fruit, and the polyols in stone fruit and sweeteners ending in "-ol". They draw water into the bowel and are fermented by gut bacteria into gas. In a healthy gut that is unremarkable. In a hypersensitive one it is a symptom.
Restricting them works. A network meta-analysis of the randomised trials ranked a low FODMAP diet above every comparator — including standard first-line dietary advice — for overall symptoms, abdominal pain and bloating, with a probability of 99% that it was the most effective of the diets compared[3]. That is a strong result for a dietary intervention. It is also the most restrictive option on the list, which is why it sits second in line rather than first.
FODMAPs on an Arab table
The published food lists are written for a Western kitchen, so the practical work is translating them. Onion and garlic are the two biggest fructan sources in the region's cooking and they are in almost everything — molokhia, tagines, stews, marinades, shakshuka. Garlic-infused oil is the usual workaround: the flavour compounds are fat-soluble, the fructans are not, so oil carries the taste without the trigger.
Pulses are the other collision. Fava beans, chickpeas and lentils are the backbone of foul, falafel, hummus, koshari and lentil soup, and all of them are high in galacto-oligosaccharides. Canned and well-rinsed pulses in small portions are better tolerated than home-cooked dried ones, but during a trial most of that food group comes off the table, which is precisely why protein needs attention while the restriction runs.
What stays is more than it sounds: rice, potatoes, eggs, meat, chicken and fish, hard cheeses, lactose-free milk and most yoghurt-free dairy swaps, carrots, cucumber, courgette, tomato, aubergine in moderate amounts, oranges, strawberries, grapes, and dates kept to a small quantity rather than a bowl. Baladi bread is a fructan load; sourdough and rice-based alternatives are easier.
Reintroduce, or you have traded one problem for another
A low FODMAP diet is a diagnostic test with a deadline, not a way of life. The restriction phase runs two to six weeks — long enough to know whether it helps, short enough not to become permanent — and is then followed by structured reintroduction, one FODMAP group at a time, to find which ones actually matter to you and in what quantity[4]. Most people discover they react to one or two groups, not to all of them, and get most of their food back.
Staying in the restriction phase indefinitely is the common failure. It narrows the diet, strips out the fermentable fibre the gut's own bacteria feed on, makes eating with other people miserable, and quietly pushes energy intake down — which is how a gut problem turns into an under-eating problem. If you want to see how a sensible intake is put together in the first place, the guide on how your daily calories are calculated shows the arithmetic, and the one on how much protein you actually need matters more than usual during a stretch with no lentils in it. Guidelines are also clear that this diet should be run with a dietitian rather than off a phone screen[2].
What to write down
The only thing that identifies your triggers is a record kept while you are changing one variable at a time: the meal, roughly how much, the time, and the symptoms in the hours afterwards. Memory is a poor witness here, because the gap between a meal and the symptom is often long enough to pin the blame on the wrong dish. Keeping that log in the place you already type — logging meals in a WhatsApp chat — means the diary survives the four weeks it needs to survive to be useful.
Then look for patterns rather than culprits. IBS symptoms also track sleep, stress and the gaps between meals, so a food that seems to cause trouble on a bad week and none on a calm one is telling you something real about how this condition works.
Sources
- Sperber AD, Bangdiwala SI, Drossman DA, et al. Worldwide prevalence and burden of functional gastrointestinal disorders: results of Rome Foundation Global Study. Gastroenterology 2021;160(1):99–114. ↩
- Vasant DH, Paine PA, Black CJ, et al. British Society of Gastroenterology guidelines on the management of irritable bowel syndrome. Gut 2021;70(7):1214–1240. ↩
- Black CJ, Staudacher HM, Ford AC. Efficacy of a low FODMAP diet in irritable bowel syndrome: systematic review and network meta-analysis. Gut 2022;71(6):1117–1126. ↩
- Monash University, Department of Gastroenterology. The three phases of the low FODMAP diet. ↩
- National Institute for Health and Care Excellence (NICE). Irritable bowel syndrome in adults: diagnosis and management. Clinical guideline CG61. ↩