Digestion & gut

Irritable bowel: the FODMAP diet

Bloating, pain, unpredictable transit? A low-FODMAP diet relieves 70–75% of IBS patients. Here's how to run it safely in three supervised phases, with personalised dietitian support in Luxembourg.

Gabriela Ferent, qualified dietitian · affiliated with the CNS
4 min read
14 July 2026
Kitchen countertop with glass jars of quinoa and buckwheat and low-FODMAP fresh produce

Understanding IBS and FODMAPs

Irritable bowel syndrome affects about 10% of European adults. FODMAPs — Fermentable Oligo-, Di-, Monosaccharides And Polyols — are short-chain carbohydrates that are poorly absorbed and ferment in the colon, causing gas, bloating, pain and altered transit in sensitive people.

3-phase FODMAP protocol1Elimination4 to 6 weeksReduce fermentableFODMAPs to calmdigestive symptoms2Reintroduction6 to 8 weeksTest each FODMAPfamily to identifytolerance thresholds3PersonalisationLong termBroad, sustainable dietrestricted only to foodsthat trigger symptomsThe restriction phase is temporary and supervised.Illustrative schematic — indicative timelines, protocol to be personalised.

A supervised framework, not permanent exclusion

The elimination phase is temporary: it lasts only 4 to 6 weeks. Reintroduction is essential to preserve microbiota diversity and avoid deficiencies. This protocol should be run with dietitian support.

Phase 1 — Elimination (4 to 6 weeks)

Goal: sharply reduce FODMAP intake to see whether symptoms improve. This phase is temporary and strictly supervised — it is not a lifestyle.

Strictly limit

  • • Fructans: wheat, rye, onion, garlic, artichoke
  • • GOS: legumes (chickpeas, lentils, beans)
  • • Lactose: milk, standard yogurts, fresh cheeses
  • • Excess fructose: apple, pear, mango, honey
  • • Polyols: sugar-free gum, plum, cherry, mushroom

Favor

  • • Rice, quinoa, oats, buckwheat, gluten-free bread
  • • Meat, fish, eggs, firm tofu
  • • Aged cheeses (parmesan, comté), lactose-free milk
  • • Carrots, zucchini, spinach, cucumber, potatoes
  • • Low-FODMAP fruits: kiwi, orange, strawberry, grape, blueberry

Phase 2 — Reintroduction (6 to 8 weeks)

Each FODMAP family is reintroduced separately, one test food at a time, over 3 days at increasing doses. The goal is to pinpoint your triggers and tolerance thresholds.

One test food per family (e.g. honey for fructose, milk for lactose)
Three progressive doses over 3 consecutive days
Symptom diary rated 0–10 (bloating, pain, transit)
⏸️ 2–3 low-FODMAP wash-out days between tests

Phase 3 — Personalization (lifelong)

You build a sustainable, as-varied-as-possible diet that only excludes poorly tolerated FODMAPs at problematic doses. This phase broadens the diet, restores microbiota diversity and prevents deficiencies.

  • Reintroduce tolerated FODMAPs to feed the microbiota
  • Periodically retest initially excluded foods
  • Manage stress (yoga, breathing, CBT)
  • Targeted probiotics if indicated (Bifidobacterium infantis)

Who is this protocol for?

The FODMAP diet is indicated in confirmed IBS after medical work-up has ruled out celiac disease, IBD and other organic conditions. It is not recommended for children, pregnant or breastfeeding women, patients with eating disorders, or as a comfort diet without indication.

CNS coverage in Luxembourg

CNS coverage is possible with a compliant prescription for Annexe E conditions, notably IBD (Crohn's, ulcerative colitis) and coeliac disease. Irritable bowel syndrome is not listed as such: a private consultation remains available. Personalized supervision keeps the protocol nutritionally safe and avoids deficiencies from prolonged, unsupervised exclusion.