Understanding FODMAPs Part 1 - What Are FODMAPs and What Happens When We Eat

Said “FOD-MAP” this is an acronym for Fermentable Oligosaccharides Disaccharides Monosaccharides And (yes - the A stands for And) Polyols. 

In English, they are a group of slowly absorbed or indigestible, short-chain carbohydrates. Even that is a little too long to say and so the people who pioneered this idea decided to shorten things down to the acronym FODMAP. 

One of the key attributes of FODMAPs is the fact they are poorly absorbed and move through our digestive system slowly which leads to two key things within the body. Before going into what those two things are it’s important we quickly touch on some basic human anatomy and physiology. 

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Our Internal Rollercoaster - The Digestive System

A healthy digestive system is a crucial part of a healthy human body. It is where we absorb the goodness from everything we consume which we then use to keep our bodies moving and functioning well. Our entire digestive tract is a long tube spanning from our mouth to our anus with interconnected compartments. It could be thought of as a long winding roller coaster with different parts of the ride, some fast, some slow, some stops, and some places for people to get off throughout. Here’s what I mean. 

When we eat, food first passes into our mouth where we (hopefully) chew to begin the digestion process by physically breaking our food down. We then swallow and it quickly moves down our esophagus and into our stomach within seconds. Food will then stay in our stomach where it is exposed to secretions like acid and enzymes which help to break our food down. Also while stopping here food is being squished by the stomach as it contracts, which helps to mix our food with the stomachs secretions thus further helping to break it down. It is then fed into the small intestine which is where a lot of the magic (absorption) happens. Before our food is absorbed though it needs to be exposed to some more enzymes that are found in our small intestine. These enzymes help to break down the contents of our food into pieces that are small enough/suitable to be absorbed through the wall of our small intestine. Think of this as the roller coaster stopping and people exiting the ride because they have had enough. We absorb most of our nutrients through the small intestine and then the bits that don’t get absorbed pass into the large intestine. This is where we absorb a lot of our water as well as some of our electrolytes. It is also the home to the vast majority of our gut bacteria. As it passes through here losing water and electrolytes our gut bacteria also get fed with whatever has made it through to this part of the ride. Once through the large intestine, it is stored in our rectum before being expelled into the toilet.    

What does that have to do with FODMAPs?

So why was that explanation of the digestive system so important? Well, as I was saying FODMAPs are poorly absorbed which means they don’t get off the ride when they’re supposed to (the small intestine) and instead stick around a little bit longer which causes a couple of things. 

​Due to not being absorbed well these carbohydrates pull/hold water inside our intestine which can cause an increase in pressure in our gut. The other consequence is they pass through the small intestine and into the house of our gut bacteria - AKA the large intestine. Important to note here the F in FODMAP stands for fermentable, which in this case means these carbohydrates are able to be metabolized (eaten/broken down) by the microorganisms (like bacteria) in our intestine. This is great for our gut bacteria as they get to feast, generally, it’s also really good for us because we want to feed these gut bacteria, however, this is not so good for people with a sensitive digestive system, like those with Irritable Bowel Syndrome (IBS). With fermentation comes gas, with gas comes an increase in pressure in the tube that is our large intestine (think of someone blowing air into a balloon, your intestine is the balloon), and thus this can lead to some of the symptoms associated with IBS like abdominal pain, constipation, or diarrhea. This same increase in pressure occurs as a result of the FODMAPs pulling water into our intestines, again potentially leading to some gastrointestinal symptoms in those with a sensitive gut. 

Summary
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FODMAP is an acronym for a group of carbohydrates that don’t get absorbed well by humans. This is a normal thing and is often beneficial for our gut bacteria because it means they get to feast. However, a byproduct of them feasting is the production of gas and a consequence of these carbohydrates sticking around is they also hold more water in our gut. Both of these things can contribute to symptoms in people with a sensitive gut, such as those with IBS. 

Part two will be released next week breaking down each of the FODMAP groups and explaining where you find FODMAPs followed by part three which will go into IBS and the low FODMAP diet is more detail.

For those who you have IBS and are feeling a little lost, confused or want more help get in touch today.

Thanks for reading. 

​Marco

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