Are you actually intolerant or is it FODMAPs?

Almost everyone has at least one food they think they react to. The vast majority of those reactions aren't classic allergies and they're not even classic intolerances. They're FODMAPs, fermentable short-chain carbohydrates that pull water into the gut and ferment into gas. Sorting which is which saves years of unnecessary food avoidance.

FODMAPs stands for Fermentable Oligo-, Di-, Mono-saccharides And Polyols. The main groups are fructans (in wheat, garlic, onion), galacto-oligosaccharides (in legumes, soy), lactose (in milk products), excess fructose (in honey, mango, apple), sorbitol (in apple, stone fruit, sugar-free gum) and mannitol (in cauliflower, mushrooms).

In a normal gut, FODMAPs cause harmless gas. In a sensitive gut, the same gas plus the water FODMAPs pull into the small intestine causes pain, bloating and altered bowel habit.

• Lactose intolerance: real, common, and easy for a doctor to confirm. The reaction usually starts within a few minutes to a few hours of dairy. Most people who are lactose intolerant tolerate hard cheese and live yoghurt fine.
• Coeliac disease: an immune reaction to gluten, confirmed by a blood test (tTG-IgA) and a small camera-test sample. Strict gluten-free for life.
• True wheat allergy: rare, with hives or breathing trouble within minutes of eating. That one belongs with an allergy specialist.
• Histamine intolerance: contested as a label, but the pattern (flushing, headache after wine and aged cheese) is real for some.
• Caffeine sensitivity: real but often mistaken for general anxiety.

• Wheat intolerance → usually fructans (a FODMAP), not gluten. Sourdough often tolerated because long fermentation breaks down fructans.
• Onion/garlic intolerance → fructans again. Cooked vs raw rarely matters; dose matters.
• Apple/stone fruit intolerance → sorbitol or excess fructose.
• Bean intolerance → galacto-oligosaccharides. Soaking and slow cooking helps, and an alpha-galactosidase enzyme supplement helps some people with the gas.
• Cauliflower/mushroom intolerance → mannitol.
• Sugar-free gum/sweets intolerance → sorbitol or mannitol again.

1. Rule out coeliac first: a blood test from your doctor, done while you are still eating gluten. Don't cut gluten before testing or you'll get a false negative.
2. Try a 4-week strict low-FODMAP elimination. Use the Monash app for the food list. Symptoms usually improve within the 2-6 week restriction phase if FODMAPs are involved.
3. Reintroduce ONE FODMAP group at a time, in increasing doses across 3 days, with rest days between groups.
4. Keep a daily symptom log. Patterns are clearer in writing than in memory.
5. After 6-8 weeks of structured reintroduction you'll know which groups you tolerate, which you tolerate at moderate doses, and which trigger symptoms.
6. Most people end up tolerating 4-5 of the 6 groups in normal portions and being careful with 1-2.

Long-term avoidance of foods you're not actually intolerant to costs you. It restricts diet diversity and consistently lowers beneficial Bifidobacteria, which is why it is not meant to be permanent. It increases anxiety around eating. It makes social eating harder. And it usually doesn't reflect what's actually happening in your gut. Spending 10 weeks (4 elimination + 6 reintroduction) to find your real picture saves years of unnecessary restriction.

• IBS severe enough to disrupt work or sleep deserves specialist help, arranged through your doctor.
• Suspect coeliac (anaemia, weight loss, family history), get the test before any dietary change.
• Eating disorder history, restrictive diets are risky and need supervised support.
• Vegetarian/vegan and worried about nutrient gaps during elimination, work with a registered dietitian.
• Pregnancy or trying to conceive, wait until later or do this with dietitian supervision.