FODMAP Categories
FODMAP is an acronym representing four distinct categories of fermentable, short-chain carbohydrates that are poorly absorbed in the small intestine: Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. 1
The Four FODMAP Categories
1. Oligosaccharides
These are complex carbohydrates consisting of multiple sugar units:
- Fructans (fructo-oligosaccharides/FOS): Found in wheat, onions, garlic, chicory root, Jerusalem artichoke, and cereal grains 2
- Galacto-oligosaccharides (GOS): Present in legumes including beans, chickpeas, lentils (raffinose, stachyose, verbascose) 2
These are the most abundant dietary fibers in wheat products, pasta, breads, and breakfast cereals 1
2. Disaccharides
Double sugar molecules:
- Lactose: The primary disaccharide of concern, found in milk and dairy products 3
- Consists of glucose and galactose units
3. Monosaccharides
Single sugar molecules:
- Excess fructose: When fructose is present in greater amounts than glucose in foods, it becomes poorly absorbed 3
- Found in honey, certain fruits, and high-fructose corn syrup
4. Polyols
Sugar alcohols used as sweeteners:
- Sorbitol and mannitol: Naturally occurring in some fruits and vegetables, also used as artificial sweeteners 3
- Xylitol: Used in sugar-free products
- These have high osmotic activity 1
Key Physiological Properties
All FODMAPs share three critical characteristics that trigger gastrointestinal symptoms 1, 4:
- Low digestibility in the upper gastrointestinal tract
- Small molecular size and high osmotic activity, which draws water into the intestinal lumen
- Rapid bacterial fermentation in the proximal colon, producing gas
These properties collectively cause abdominal distention, bloating, gas production, diarrhea, and abdominal pain, particularly in individuals with visceral hypersensitivity such as those with irritable bowel syndrome 1.