FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols – basically a group of short-chain carbohydrates that are poorly absorbed in the small intestine.

What Makes a Food “High FODMAP”?

A food is categorized as high FODMAP based on specific threshold values for each carbohydrate type per standard serving size:

Quantitative Thresholds:

• Fructose (excess): >0.2g more fructose than glucose per serving
• Lactose: >1g per serving
• Fructans: >0.2g per serving
• Galacto-oligosaccharides (GOS): >0.2g per serving
• Polyols (sorbitol, mannitol): >0.2g per serving

Foods containing these amounts trigger symptoms because they’re poorly absorbed in the small intestine, drawing water into the gut and fermenting rapidly when they reach the colon.

The Five FODMAP Categories

1. Oligosaccharides

Fructans – chains of fructose molecules that humans lack enzymes to break down

Galacto-oligosaccharides (GOS) – chains of galactose molecules found primarily in legumes

2. Disaccharides

Lactose – milk sugar requiring the enzyme lactase for digestion

3. Monosaccharides

Excess Fructose – free fructose not balanced by glucose, poorly absorbed when in excess

4. Polyols

Sugar alcohols including sorbitol, mannitol, xylitol, maltitol, and isomalt – naturally occurring or used as sweeteners

 

Important Considerations

Serving Size Matters: Many moderate FODMAP foods become high FODMAP in larger servings. For example, avocado is low FODMAP at 1/8 of a fruit but high FODMAP at 1/4 fruit.

Stacking Effect: Eating multiple moderate FODMAP foods in one meal can create a cumulative high FODMAP load, triggering symptoms even when individual foods would be tolerable.

Individual Variation: FODMAP tolerance is highly individual. Some people react strongly to fructans but tolerate lactose well, while others have the opposite experience.

Processing Changes FODMAP Content: Cooking methods, ripeness, and food processing affect FODMAP levels. Unripe bananas are lower FODMAP than overripe ones. Canned lentils have lower GOS than dried lentils due to leaching into the liquid.

Not Forever: The low FODMAP diet is designed as a diagnostic tool, not a permanent eating pattern. After identifying triggers through systematic reintroduction, most people can include many moderate and some high FODMAP foods without symptoms.

The Three-Phase Approach

Phase 1 – Elimination (2-6 weeks): Strictly avoid high FODMAP foods to allow symptoms to settle and establish a baseline.

Phase 2 – Reintroduction (8-12 weeks): Systematically test individual FODMAP groups to identify personal triggers. Test one FODMAP type at a time in increasing amounts.

Phase 3 – Personalization (Ongoing): Create a sustainable long-term diet that includes as many foods as individually tolerated, avoiding only confirmed triggers.

Working With Healthcare Professionals

The low FODMAP diet is complex and should ideally be undertaken with guidance from a registered dietitian experienced in digestive health. Professional support helps ensure nutritional adequacy, proper reintroduction technique, and identification of other potential dietary triggers beyond FODMAPs.

Many high FODMAP foods like garlic, onions, wheat, and legumes contain valuable prebiotics that feed beneficial gut bacteria. Long-term unnecessary restriction can negatively impact gut microbiome diversity, which is why personalization based on individual tolerance is crucial.

Complete FODMAP Food Reference Chart

 

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