The low FODMAP low-down

The low FODMAP diet is the shiny new diet we keep hearing about. It is popping up everywhere, it’s in my insta feed, on products, supplements and everyone is talking about it. So for today’s blog I wanted to run you through what exactly is it, who is it for (and who is it NOT for), and most importantly is it actually a healthy diet? 

FODMAP is an acronym for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols, now I know you’re probably sitting there thinking ‘oligo what?’ And I don’t blame you. Essentially these are all short chain sugars or carbohydrates which are found in many foods naturally but also can be added to foods during processing. These carbohydrates as the name suggests are fermented by the bacteria in our large bowel and they are a substrate for our gut microbes. Below is a table of some of the common high FODMAP foods (you will notice most of them are incredibly healthy foods).

Image from Monash FODMAP website

Image from Monash FODMAP website


The low FODMAP diet restricts these fermentable sugars or carbohydrates to restrict the amount of substrate available for fermentation by the bacteria. Now if you are up on all things #guthealth you might be thinking, 'hang on isn’t fermentation by our gut microbes good for us?!’. Yes it absolutely is. Unfortunately though for some people with Irritable Bowel Syndrome (IBS) this fermentation process is incredibly painful and symptomatic causing excessive bloating, diarrhoea and cramping. Not really ideal. 



What is the PROCESS:

A low FODMAP diet is a bit different to your typical diet (hate that word). The low FODMAP diet is a process. It is not a diet that you just get a list and exclude foods, I know many of you may have been instructed this before and I am deeply sorry you haven’t been given the proper education around the diet. 

When someone embarks on a low FODMAP diet the process is that they eliminate the high FODMAP foods (and obviously replace them with low FODMAP options) for a short period of time, usually 2-4 weeks. After which the FODMAP foods are systematically re-introduced in a dose-response method. Essentially you want to know, which FODMAPs are causing the issues as it is unlikely they all are, in fact I am yet to see someone who is symptomatic with ALL of them. You also want to know how much of that FODMAP containing food do you need to consume before you get a symptom. As with most food intolerances, small amounts are often well tolerated but larger amounts illicit a symptom. Finally you want to know what that symptom is, and how long it lasts for, because you know, this makes planning social situations a little less stressful. I kinda want to know if it’s going to be explosive diarrhoea in 5 mins versus bloating over the next hour. 

After this re-introduction period you should have a bit more of a road map for which foods are well tolerated and which cause symptoms for you. Now this isn’t set in stone, if you don’t respond well to garlic for example, this doesn’t mean you can’t have garlic ever again! Periodic re-introduction is essential as our gut is ever evolving and the other factors that play a role in our symptoms are also changing (sleep, stress, etc). So while you may get horrendous pregnancy belly with garlic now, in 6 months time this may not be the case. 

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Who Might Benefit:

This diet was coined here in Australia, by the team at Monash for those who suffer with IBS. It is not a diet for everyone and there are a few reasons why it isn’t, I will explain these reasons soon. When I work with my IBS clients we use the low FODMAP diet as second line therapy in those with medically diagnosed IBS with symptoms of frequent and recurring abdominal cramping and pain, bloating and altered bowel habits. Note I say second line therapy, I avoid elimination if possible and have had huge success in doing so. 


What are the risks?

So it isn’t all sunshine, roses and normal poops. There are some drawbacks when it comes to the low FODMAP diet. Firstly, it is a very restrictive diet and restrictive of many healthy foods. Due to it’s restrictive nature this diet is not appropriate if you have an eating disorder. Your dietitian will work with you on strategies to help keep you comfortable during your recovery.


Secondly, the way this diet provides it’s symptomatic benefits is through reducing the substrate for fermentation by our gut microbes. This fermentation process produces byproducts called short chain fatty acids that are incredibly beneficial for us. We also know our gut microbes play a large role in many aspects of health including immunity, inflammation, disease risk plus much more. So by reducing their food (substrate) by restricting our FODMAP intake we are starving off some of these microbes and in fact we have research to prove this. Following a strict low FODMAP diet reduces the diversity of our gut microbiome. This is why it is so essential to introduce as many FODMAPs as possible during that re-introduction phase and also why we shouldn’t embark on this diet if we don’t absolutely have to and why I use this diet as second line therapy in IBS not first! 

All in all the low FODMAP diet is incredibly effective when used on the right people, at the right time, with the right guidance. I should mention, I strongly suggest doing this under the guidance of a dietitian who works in the space of gastrointestinal nutrition so you can step through this process swiftly, with as little stress as possible and do it properly the first time. It is not a diet for everyone and is certainly not a healthy gut diet, in fact quite the opposite. 


If you are wondering what is a healthy gut diet that will actually FEED your microbiome looks like I have developed a 7 day meal plan with recipes to give you an overview of what that might look like. Click here to get your meal plan

Over the coming weeks I will be taking you through more of the topics we touched on here including sleep, stress and other methods for managing IBS so be sure you are signed up to receive emails so you don’t miss a beat.

Chat soon, 

Marika x 

Marika Day