FODMAP Explained: “M” Stands for Monosaccharides

Published on: 07/08/2019

Welcome back to my “FODMAP Explained” Series! This is a set of articles I have dedicated to explaining the acronym FODMAP and giving practical tips to avoid symptoms while including as wide a variety of foods as possible. In this post, I will discuss the “M” in the acronym FODMAP. “M” stands for monosaccharides (single-sugar units), more specifically, fructose.

The “M” in FODMAP Stands for Monosaccharides: Fructose

Why should people with IBS be concerned about fructose? Fructose is the main sugar present in fruit. We also find it in sucrose or table sugar, where it pairs up with glucose (glucose + fructose = sucrose), and in a handful of vegetables. The problem with fructose is that it is slowly absorbed and, when excess fructose is lingering in the small intestine, it attracts water. This can lead to bloating, cramps, and possibly diarrhea. It is also common for fructose the be poorly absorbed. The unabsorbed excess fructose travels to the large intestine where our friendly bacteria ferment it, triggering excess gas and bloating.

Fructose in the Low FODMAP Diet

You don’t need to eliminate all fruits or table sugar when you are in the elimination phase of the low FODMAP diet. Why? Because, as long as there is an equal amount of fructose and glucose, we can absorb fructose efficiently. On the other hand, when a fruit, vegetable, or sweetener contains an excess of fructose (compared to glucose), that’s when the intestinal tract cannot handle the absorption of fructose efficiently and symptoms may appear.

Bottom line: what can you eat?

If you have IBS and have undertaken the low FODMAP diet to help you manage your symptoms, you need to pay attention to both the type and the amount of fructose you consume. Here are a few tips:

  • Choose low-FODMAP fruits: these have equal amounts of fructose and glucose. Some examples are strawberries, blueberries, cantaloupe, oranges, and papaya. See my Balsamic Strawberries Recipe.
  • Eat them in low FODMAP serving sizes. It also helps to limit them to one serving per meal or snack (check out the Monash University FODMAP Diet App for appropriate serving sizes).
  • Avoid high-FODMAP fruits and vegetables: these have more fructose than glucose and even small amounts can lead to symptoms. Some examples are mango, apple, some dried fruit, asparagus, and snap peas. Ever wondered why snap peas are so sweet? Now you know.
  • Avoid honey, agave, and high-fructose corn syrup, as these sweeteners mostly contain fructose (and little glucose).
  • Keep the portion of sugar and anything made with sugar – cookies, brownies, etc. – small. One to three teaspoons of sugar in a beverage, or about the same amount of sugar per serving of a baked product/dessert per meal or snack are usually well tolerated.

Final Thought

In summary, while on a low FODMAP diet, you will need to limit the amount of fructose in your diet. But it’s important to remember that this is only a temporary restriction. If you pass the fructose challenge during the reintroduction phase, you can expand the amounts and types of fruit you can eat.

Everyone is different in their tolerance, and you will need to find out your own threshold for fructose. If you find that fructose is a trigger for you, keep following these tips but try and re-challenge fructose every 3-6 months. IBS symptoms come and go and change over time, and you may find you can better tolerate fructose later on.

Want to learn more?

Check out more Low FODMAP Diet Basics

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I’m a registered dietitian with a passion for helping women with IBS find their way back to eating without fear of painful gut symptoms and without unnecessary diet restrictions.

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