(Updated 2018) by Lee Martin MSc RD
Since I originally wrote this article in 2015 the 3 phases of the low FODMAP diet have gradually become more talked about. In particular the final third phase which is known as the ‘modified FODMAP diet’ or ‘adapted FODMAP diet phase’ has received a lot more interest. The final phase of the low FODMAP diet has also been described as the ‘FODMAP personalisation phase’. In fact the term ‘FODMAP personalisation’ is what we used in our recent evidenced based review of the low FODMAP diet in clinical practice. The review paper is open access and available here: ‘The low FODMAP diet in the management of irritable bowel syndrome: an evidence-based review of FODMAP restriction, reintroduction and personalisation in clinical practice’
Below is the original article I wrote, with a few updates, which describes the background research I was involved in that has increased our understanding of the three phases of the low FODMAP diet…
The 3 phases of the Low FODMAP diet
What is a modified or adapted FODMAP diet?
There is a new term starting to emerge in relation to the low FODMAP diet and this is the modified FODMAP diet.
Put simply this is the long term diet the majority of people follow after completing the reintroduction phase of the low FODMAP diet.
People with IBS who have been fortunate enough to see an experienced FODMAP dietitian will have had explained to them that there are actually 3 phases to a low FODMAP diet. Those who could not get access to a dietitian or have chosen to try the low FODMAP diet themselves may probably not have realised the low FODMAP diet has 3 phases. Certainly if you obtain most of your information from the internet the reintroduction phase and the long term maintenance phase which involves a modified FODMAP diet are rarely mentioned. I have to admit the research into FODMAPs and IBS is pretty slim on these important phases too unfortunately! The figure shows these 3 phases and is explained below.
So what are the 3 phases of the low FODMAP diet?
1. The first phase is the low FODMAP restriction (or elimination) diet. This is what most people know as the low FODMAP diet but this phase of the diet should only be followed for 2-6 weeks.
2. The second phase of the diet is the reintroduction phase. This involves both re-challenging and reintroducing FODMAPs to test your tolerance levels to FODMAPs and understand your FODMAP threshold. This phase takes about 10 weeks to complete. In a way it continues indefinitely as your tolerance to FODMAPs can change over time and you continue to re-challenge and reintroduce FODMAPs. More on reintroducing FODMAPs here.
3. The final phase is termed the personalisation phase and involves a modified (or adapted) FODMAP diet. Once you have completed the reintroduction phase and reintroduced FODMAPs back into your diet most people will still restrict some high FODMAP foods. This combination of eating high FODMAP and low FODMAP foods to personal tolerance results in a modified low FODMAP diet.
The final terminology for these 3 phases has yet to be agreed or published but will be similar to what is discussed above. (UPDATE 2018: The team at King’s College London are leading the way on this, check out the paper we published on all 3 phases of the low FODMAP diet in clinical practice here ‘The low FODMAP diet in the management of irritable bowel syndrome: an evidence-based review of FODMAP restriction, reintroduction and personalisation in clinical practice’)
Research highlighting the three phases of the low FODMAP diet
There is limited research available on what people do once they have completed the 2-6 week low FODMAP diet. In 2015 I presented an abstract while working at King’s College London at the Digestive Diseases Federation conference (see programme here) which looked at the long term effects of the low FODMAP diet in the UK. The research answered some very interesting questions….
Question 1. Do people reintroduce FODMAPs after starting a low FODMAP diet?
In fact 97 out of 103 people completed the reintroduction phase.
Showing that with the education and support from an experienced FODMAP dietitian nearly everyone is able to complete the reintroduction phase.
2. What sort of diet do people follow in the long term after completing the low FODMAP restriction diet and the reintroduction phase?
Out of the 103 participants when followed up one year later:
- 78 of them continued to follow an adapted low FODMAP diet. Meaning they had reintroduced FODMAPs to their own tolerance levels.
- 19 followed a normal diet. Meaning they had reintroduced FODMAPs and no longer followed any FODMAP restrictions.
- 6 continued to follow a low FODMAP restriction diet in the long term (a year later).
Therefore the vast majority of people do reintroduce FODMAPs but continue to follow a modified FODMAP diet as their ‘normal’ diet.
3. After you have reintroduced FODMAPs do you still have relief and control of your IBS symptoms in the long term?
There are two important statistical points here.
- First of all 61% of people found relief of their IBS after following a low FODMAP restriction diet. This is similar to other studies looking at the effectiveness of the restriction phase of the low FODMAP diet.
- Secondly and most importantly in those 61% of people 70% of them continued to have relief of their symptoms a year later.
This shows that in the vast majority of people who find the low FODMAP restriction diet effective, even once they have reintroduced FODMAPs they still have relief of their IBS symptoms in the long term.
The abstract of my study and presentation from the DDF event is available here.
It is great that questions regarding all three phases of the FODMAP dietary treatment are starting to be answered as it helps the low FODMAP diet become a long term treatment option for IBS symptoms. It also means that information about all three phases of the low FODMAP diet will become known to more people. Hopefully this will result in more support for those who are following only phase one of the low FODMAP diet and are unnecessarily restricting their diet.
The study also looked at quality of life, the long term nutritional adequacy and acceptability of the diet with some really interesting findings which I will discuss in a later post.
UPDATE 2018: The full paper for which I presented the abstract from above has been published in Neurogastroenterology & Motility (January 2018) and is available for open access here: Long-term impact of the low-FODMAP diet on gastrointestinal symptoms, dietary intake, patient acceptability, and healthcare utilization in irritable bowel syndrome
Recently Monash University have also published a blog post on the three phases of the low FODMAP diet which you can read here. Additionally a useful and practical article on the modified FODMAP diet can be found on ‘A little Bit Yummy’ here.
Good news! The first ever book dedicated to reintroducing FODMAPs is now available to purchase on Amazon. The book is titled ‘Re-challenging and Reintroducing FODMAPs – A self-help guide to the entire reintroduction phase of the low FODMAP diet’. Click on the logo for more details.
We recently travelled around the world and blogged about following a modified low FODMAP diet. See more on our FODMAP travel section.