Is Onion High FODMAP?
Onions contain dense concentrations of fructo-oligosaccharides. Even small amounts found in commercial broths, sauces, and seasoning rubs are sufficient to trigger colonic gas distension, abdominal cramps, and diarrhea in sensitive individuals 6 to 18 hours after ingestion.
None in bulb form (0g)
Safe for most sensitive digestive tracts
1/4 slice (11g+)
Exceeds colonic tolerance limit
12 hours
6 to 18 hours (colonic fermentation)
How Onion affects your digestive tract
Like garlic, onions contain prebiotic fructan polymers. When they reach the cecum and ascending colon, bacteria rapidly ferment them, generating osmotic fluid draw into the bowel lumen followed by volatile gas production.
Common symptom manifestations
Gentle alternatives to Onion
The dark green leaf portions contain almost zero fructans and are low FODMAP up to 75g. Discard the white bulb.
The green upper leaves are low FODMAP up to 54g. Avoid the white lower bulb.
Low FODMAP at standard culinary serving sizes.
Test your personal tolerance for Onion
FODMAP tables provide population averages. Some people tolerate Onion without issues, while others react to small trace amounts.
GutLog 1.5.6 includes an Active Diet Tracker with a 3-Phase Elimination Stepper. Test individual food challenge groups with automatic 3-day washout countdowns and 4-hour tag deduplication.
- Tests reactions across 6 digestion lag windows (2h to 36h)
- Calculates Poisson arrival baseline rates and lift scores
- Monitors symptom deltas for pain, bloating, and stool form
- Operates 100% on-device with zero cloud health tracking
Frequently asked questions about Onion
Are cooked onions easier to digest than raw onions?
No. Cooking softens the plant cell walls but leaves the chemical fructan chains intact.
Is onion powder high FODMAP?
Yes. Onion powder is dehydrated and concentrated, containing even higher fructan density per gram than fresh onion.
Track Onion in your daily food log
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