What are FODMAPs? (Details)

FODMAPs Summary

[FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. 

These are names for short chains of sugars (carbohydrates) that are found in the diet.

These sugars aren’t well absorbed in the small intestine. This means they travel to the large intestine where they are fermented by bacteria, which can cause troublesome gas and bloating. Once in the large intestine, these sugars also attract water into the bowel, triggering loose stools and diarrhoea.

What are FODMAP Summary?

  • Fermentable are sugars that aren’t well absorbed in the small intestine
  • Oligosaccharides are chains of 2-10 sugars joined together. Fructans (chains of fructose) and galactans (chains of galactose) are FODMAPS.
  • Disaccharides are two sugars joined together. The disaccharide lactose (the sugar found in milk) is a FODMAP.
  • Monosaccharides are single sugars. The monosaccharide fructose is a FODMAP.
  • AND
  • Polyols are sugar alcohols usually found in calorie free sweeteners.

Not all sugars are FODMAPs and not all people are sensitive to FODMAPS. People with IBS tend to have more symptoms as a result of eating FODMAPs, which is why they can benefit from a low FODMAP diet.

FODMAPs in Detail


  • These [highlight]poorly absorbed sugars[/highlight] are fermented by bacteria in the large intestine (bowel).


The major types of oligosaccharides found in food that are FODMAPs are fructans and galacto-oligosaccharides (GOS).

  • Oligo means few, and saccharide means sugar. So these are individual sugars, joined together to make a chain.
  • The two main oligosaccharides that are FODMAPs are:
    • Fructans, made up of fructose sugars joined together to make a chain (with glucose at the very end). Fructans are chains of fructose molecules with a glucose molecule at the end. The main dietary sources of fructans include wheat products (breads, cereals, and pasta) and some vegetables, such as onions. Additional sources of fructans are fructo-oligosaccharides (also called oligofructose and FOS) and inulins, which are added to some foods, such as certain yogurts and milk, as a prebiotic No one is able to digest fructans, and if you have IBS you should minimize your intake of them. Fructans are probably the most common FODMAP to cause symptoms of IBS, probably because most people eat a lot of them. They occur in a wide variety of foods and in large amounts in our food supply. Foods are considered a problem for sufferers of IBS if they contain more than 0.2 gram of fructans per serving of food for cereals and grains, and 0.3 gram of fructans per serving of food for other foods. The main food sources of fructans are some vegetables and grains, as well as a small number of nuts and fruits.
    • Galacto-oligosaccharides (GOS), made up of galactose sugars joined together, with a fructose and glucose at the very end. Galacto-oligosaccharides (GOS) are chain molecules formed from galactose sugars joined together with a fructose and glucose at the end. Raffinose and stachyose are the most common GOS found in food. They occur in many legumes, such as beans, lentils, and chickpeas. Like fructans, GOS cannot be digested or absorbed by anybody and they should be avoided if you have IBS. High-GOS foods are those that contain more than 0.2 grams per serving.


  • Di means two, and saccharide means sugar. colo these are two individual sugars, joined together to make a double sugar.
  • The important FODMAP disaccharide is lactose, made up of an individual glucose sugar joined to an individual galactose sugar.

Only one disaccharide can potentially act as a [highlight]FODMAP in food—lactose.[/highlight]

Lactose is a double sugar that occurs naturally in all animal milks, including milk from cows, sheep, and goats. Made up of two digestible sugars called glucose and galactose, it is broken down in the small bowel into its component sugars by an enzyme called lactase. Lactose-intolerant people, however, have low levels of lactase and can therefore only break down a very small amount of the lactose they consume. Such people may benefit from reducing their lactose intake as part of the low-FODMAP diet.


  • Mono means one, and saccharide means sugar. So these are individual sugars.
  • The important FODMAP monosaccharide is [highlight]excess fructose[/highlight]. Not all fructose needs to be avoided. Only foods that contain more fructose than glucose (or “excess fructose” foods) need to be avoided on the low-FODMAP diet.
  • If a food contains more glucose than fructose, or if glucose and fructose are present in equal (“balanced”) amounts, then it is suitable on the low-FODMAP diet.
  • If a food (for example, a piece of fruit) contains more glucose than fructose, or equal amounts of fructose and glucose, it is suitable to eat; however, only one piece of suitable fruit should be consumed at a time. This doesn’t mean you can only have one piece of fruit per day! You can have several, but spread them out so that you only have one per sitting.

Fructose, a single sugar, is often referred to as the [highlight]“fruit sugar.”[/highlight] It is found in every fruit, in honey, and in high-fructose corn syrup. It is a component of table sugar (also called sucrose or cane sugar) and is also found in some vegetables (e.g., sugar snap peas) and grains (e.g., wheat).


Polyols, also called sugar alcohols, are often given names that end in “ol” and include sorbitol, mannitol, maltitol, xylitol, polydextrose, and isomalt. [highlight]Polyols occur naturally in some fruits and vegetables[/highlight].

  • A polyol is made up of a sugar molecule with an alcohol side-chain. Polyols are also known as sugar alcohols, but I promise they won’t make you feel intoxicated!
  • The two polyols most commonly occurring in foods are sorbitol and mannitol.

The Worst FODMAP?

While there are a lot of FODMAPS foods, the worst of all are any foods that contain [highlight]fructose – the fruit sugar[/highlight].

Fructose is especially troublesome for sufferers of IBS because of how prevalent it is in our modern diets. You can find it in all fruits and fruit-related products. It’s also used as a sweetener in literally thousands of products in the form of high-fructose corn syrup (HFCS). Everyone has heard of HFCS because it is simply in almost any packaged or processed food that you could purchase, no matter where you are in the world. This is what makes fructose the worst FODMAPS food – not because it is any worse for your intestinal tract, but simply because it is so common that it feels impossible to avoid.

About The Author

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top