What is FODMAP and why should I care?

fodmapLow carb, high protein, paleo, 5-2 – why is trying to find a decent eating plan that is healthy, fuels your activity and aids exercise recovery so hard? There are more “eating systems” out there with celebrity endorsements or backed by shonky science, or poorly interpreted science, than you can point a stick at.

And then there’s FODMAP. The name is an acronym of Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols. These are specific types of carbohydrates, common in western diets, that have been linked to a number of conditions such as irritable bowel syndrome.

Let’s look at what FODMAP stands for in a little more detail

F is for Fermentable. Fermentation is a chemical process where one chemical is broken down into smaller components. Fermentation relies on bacteria to do the breaking down. For example, we use yeast to ferment plant material when making alcoholic beverages. Complex materials are broken down with alcohol and gasses being one of the by-products.

O is for Oligosaccharides. The two root words oligosaccharides comes from are oligo meaning few and saccharides meaning sugars. So, oligosaccharides are chemical compounds made up of a few different sugar molecules joined together.

D is for Disaccharides. Now that we know a saccharide is a sugar, we can figure out that a disaccharide is a molecule made of two different sugars joined together.

M is for Monosaccharide. With mono meaning one, you can guess a monosaccharide is a single sugar molecule.

A is for And. Not much of a mystery there!

P is for Polyols. In chemistry, pretty much any molecule whose name ends in “ol” is an alcohol. Polyols are sugar alcohols. However, unlike other alcohols, polyols won’t get you drunk.

Now, FODMAP, as I said earlier, is all about carbohydrates. In chemical terms, sugars are carbohydrates – molecules made up of

  • Carbon (that’s the “carbo” bit)
  • Hydrogen (that’s the “hydr” bit)
  • Oxygen (that’s the “ate” bit – the suffix “ate” is used in chemistry when oxygen atoms are part of a molecule)

What do these do in your guts?

intestinesFermentation requires bacteria. And the body’s fermentation powerhouse is the large intestine, or bowel. Once FODMAPs make their way to your bowel, the bacteria in there ferment the molecules, breaking them down into smaller molecules. Some of those molecules are released as gas.

FODMAP foods also attract water to the bowel. This is a process called osmosis.

Osmosis is the movement of water from one place to another in order to equalise the concentration of something between two areas.

Let’s say you have two glasses of scotch that are connected to each other in a closed system. One is mixed weakly (small amount of scotch, more water) and the other is stronger (more scotch and less water).

You could equalise the concentration of scotch in the two glasses either by moving scotch from the stronger drink to the weaker one, or by moving water from the weaker drink to the stronger drink.

Moving the scotch is called diffusion. Moving the water is called osmosis.

So, back to the large intestine, FODMAP foods attract water resulting in bloating, constipation, diarrhoea and other painful and annoying symptoms.

To summarise – if your body is intolerant to high FODMAP foods, then you’ll likely feel gassy and bloated because of fermentation and osmosis.

What are some common FODMAP foods?

The thing about high FODMAP foods as that they are pretty pervasive. A quick look in the typical Australian pantry, or even the fruit bowl, will reveal lots of foods that are on the FODMAP map.

There are hundreds of useful resources that list high and low FODMAP foods. Here’s one from Monash University that I found that looks at various food groups and what some high and low FODMAP foods are for each category.


From http://www.med.monash.edu/cecs/gastro/fodmap/low-high.html

Is a low FODMAP diet healthier?

When looking at FODMAP, I think it’s important to consider what problem you are trying to solve. If you suffer from gut issues such as excessive flatulence, cramps or abdominal pain, constipation, diarrhoea or anything else, your first port of call ought to be getting some medical advice.

Frankly, there’s so much pseudoscience and blatant misinformation, I suggest speaking with a registered dietician to determine what is actually going on in your body.

A good thing to do before that appointment is to keep a food diary where you record everything you eat and when you ate it (yes, even that chocolate bar you snuck in!) and any symptoms (I’d probably record bowel movements such as times and some more descriptive information) and other general notes such as whether you felt fatigued, irritable or unwell.

Then, you can use the data to determine what the potential root cause might be.

That might mean your body is less tolerant of high FODMAP foods. Or it might be something more specific such as gluten intolerance or allergy. Or some other, non-dietary problem.

Without data, you won’t know.

You might find you feel better on a low FODMAP diet – that’s great. But if there’s no medical reason for a low FODMAP diet, then the old rule applies.

A healthy, balanced diet of fruit and vegetables, protein, complex carbs and fats will deliver what your body needs.

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