FODMAP group · Polyol
Mannitol on the Polyols List: Mushrooms, Cauliflower & Sweeteners
In short
Mannitol is a polyol — a sugar alcohol closely related to sorbitol and just as poorly absorbed. Unabsorbed mannitol draws water into the intestine and ferments in the colon. Its classic food sources are mushrooms, cauliflower, celery, and sweet potato, and it also appears as the added sweetener E421 in sugar-free products.
How mannitol is absorbed
Mannitol is a polyol — the P in FODMAP — sitting alongside sorbitol and xylitol. Like all polyols, it's absorbed slowly and incompletely by everyone, crossing the gut wall by passive diffusion rather than through a dedicated transporter, so some always reaches the colon. Once there it pulls water into the bowel and is fermented by gut bacteria, producing gas. For an IBS gut, that extra water and fermentation is a dependable trigger. Mannitol behaves much like sorbitol mechanically, but it turns up in a different set of foods, which is why the two are worth thinking about separately even though they share a group.
Typical symptoms
As with other polyols, mannitol's water-drawing effect skews symptoms toward loose stools, urgency, and diarrhoea, together with bloating, wind, and cramping. A large serving of mushrooms or cauliflower is a common trigger meal.
Which foods carry mannitol
Mannitol's standout natural sources are mushrooms and cauliflower, along with celery, sweet potato, and snow peas. Like sorbitol, it's also used as an added sweetener — listed as mannitol or E421 — in some sugar-free sweets, chewing gum, and medications.
High-polyol foods to limit
These foods reach a high polyol level at a realistic serving, so they're usually limited during the elimination phase. Each links to its full serving thresholds.
Safe picks low in polyol
These low-FODMAP foods don't carry a meaningful polyol load, so they make dependable swaps while you keep mannitol low.
Mannitol and sorbitol are both polyols, and our food database records one combined polyol level rather than splitting them — so the lists below reflect polyol content overall. Mannitol's signature natural sources are mushrooms and cauliflower.
How to reintroduce mannitol
Mannitol is usually challenged with a food that isolates it well, such as mushrooms or cauliflower, building the serving over three days while the rest of your diet stays low-FODMAP.
Typical test food: Mushrooms (or cauliflower)
| Step | Guide portion |
|---|---|
| Day 1 — small | a small serving of mushrooms (about a quarter cup) |
| Day 2 — medium | about half a cup |
| Day 3 — larger | about one cup |
Treat these amounts as a general pattern rather than exact doses. Because you can tolerate one polyol and not the other, mannitol is tested separately from sorbitol — go gently given the laxative effect polyols can have, and plan the challenge with a registered dietitian.
For the full method — washouts, how to read your results, and the mistakes that quietly derail people — see our guide to the FODMAP reintroduction phase.
Mannitol FAQ
What foods are high in mannitol?
Naturally: mushrooms and cauliflower above all, plus celery, sweet potato, and snow peas. As an additive it appears as mannitol or E421 in some sugar-free sweets, gum, and medicines.
Are sorbitol and mannitol tested together?
No — they're separate challenges. Both are polyols with the same mechanism, but they occur in different foods and you can react to one without the other, so reintroduction tests each on its own.
Can I eat mushrooms on a low-FODMAP diet?
Common button and portobello mushrooms are high in mannitol, but canned mushrooms (some mannitol leaches into the liquid) and certain varieties like oyster mushrooms are better tolerated. Portion size matters, and reintroduction shows your own limit.
Is cauliflower always off-limits?
Only in larger servings, and only during elimination. Cauliflower is a notable mannitol source, so small portions or a full reintroduction challenge — rather than blanket avoidance — is the low-FODMAP way to handle it.
The other FODMAP groups
This page is for general education and is not medical advice. FODMAP content varies with ripeness, processing, and brand, and IBS should be diagnosed by a doctor. Always work with your doctor or a registered dietitian before changing your diet or running reintroduction challenges. Serving thresholds draw on published FODMAP research (Varney et al. 2017) and Monash University food-composition data.