What it takes to run a FODMAP diet research study


Caroline Tuck - Research Dietitian & PhD Candidate, 29 January 2018

Ever wondered how the scientific evidence behind the low FODMAP diet was actually made? Well here’s a snap shot.

Dietary studies are not easy to run, because food and diet are so complex it means there are a lot of factors to consider. 

Firstly, the research question needs to be identified. Once we know exactly what we want to find out, or perhaps, what dietary components we want to compare, we need to design a controlled study diet. The diet needs to be, not only nutritionally adequate, but if we are comparing one thing against another, it needs to be exactly the same with the exception of the food component in question. For example, to compare a high FODMAP vs low FODMAP diet, other than the FODMAP content, everything else needs to be the same. This means the fibre, protein, sugar and fat content all need to be identical between the two diets. This can get tricky, especially when high FODMAP foods also tend to be high fibre foods, it can be hard to match them exactly.

Next, once we've planned exactly what the diets are going to be, we need to cook them! So luckily we've got some great chefs on board who help us create tasty meals for our study participants. They also must weigh out every single ingredient they use in each recipe (not so normal for an everyday chef!).

We also need to prepare other parts of the study. For example, we need to create food and symptom diaries which help our study participants tell us how they are feeling on the days of the study. Depending on the study, there may be other components involved too, such as collection of breath or stool samples.

Once we’ve got everything prepared, then we source our participants. This is where the logistics can get difficult, now we’ve got to make sure we get all the food, diaries and collection materials to each participant and back from them in time to test the samples. The recruitment stage can take many months, for example it might take at least 12 months to recruit 30 eligible participants into a study.

The team at Monash University are very grateful for the generosity of our participants who give us their time and allow us to feed them and watch what happens! After we’ve managed to find enough of these generous participants we then go through and look at the data and compare the groups to see what we can find.

From start to finish, a study will often take 2 years or more. You can now appreciate the time and effort involved in running these dietary studies! The great thing is, at the end of it all, we find out what helps and what doesn’t help our patients. So far, the results have been outstanding, with ~75% of patients with IBS feeling better on a low FODMAP diet. 

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