Did you know that not all foods have been tested for FODMAPs? The FODMAP content is unknown for a range of foods, so do these foods have a place in the low FODMAP diet? These untested foods do not need to be permanently excluded from your diet, but it is important to understand what stage of the diet you are at and when it is appropriate to trial them in your diet.

The low FODMAP diet is a relatively new diet that has emerged from research to assist with managing IBS, which means that not all foods have been tested for their FODMAP content yet. The low FODMAP diet and its influence on IBS was initially researched by a dietitian named Sue Shepherd and researchers at Monash University just over 20 years ago.

The low FODMAP diet has since been validated by multiple scientific studies for its role in the reduction of IBS symptoms.  However, there are still a range of foods that need to be tested for their FODMAP content. Research is still occurring in the area of FODMAPs, to improve our understanding of them and how they trigger symptoms in people with IBS.

Stage 1: Elimination Phase

The first stage of the low FODMAP diet is the elimination phase. This involves consuming a strictly low FODMAP diet for 2-6 weeks and having minimal IBS symptoms for 5 consecutive days. This should only be completed under the guidance of a dietitian to ensure you are still having adequate nutritional intake.

Stage 2: Challenge Phase

The second stage is the challenge phase. This is where you complete ‘challenges’ by trialling each of the FODMAPs. For the challenges, they are separated into fructan containing foods (wheat, onion, garlic and other fruits and vegetables), galactooligosaccharides, fructose, lactose, sorbitol and mannitol. Wheat, onion and garlic are all completed as individual challenges, rather than just one challenge for fructans. Only one of these will be trialled in the diet at a time, to monitor your symptoms in response to each. It is also important to complete these challenges as per your dietitian, to ensure your specific FODMAP triggers are determined accurately. Your threshold for each FODMAP will also be tested, as people can tolerate varying amounts of each FODMAP.

Stage 3: Maintenance and Personalisation

Once all challenges have been completed, your dietitian will be able to provide information on what FODMAPs you are sensitive to and need to continue limiting in your diet. This is the maintenance phase of the low FODMAP diet, as you are no longer required to avoid all high FODMAP foods, just the ones that trigger your IBS symptoms. At this stage you are able to reintroduce any foods that did not trigger your symptoms, and you will start on your own personalised version of the diet, known as the long term modified low FODMAP diet. The modified low FODMAP diet varies between people and is designed to help reduce your IBS symptoms long term while ensuring adequate intake from all core food groups. Your dietitian will also assist with increasing the variety with your knew modified low FODMAP diet.

Fodstacking as a Trigger for IBS

If you want to try a food that has not been tested, it is important to be aware of Fodstacking. This is when you consume multiple foods that contain small amounts of the same FODMAP, and on their own are each low FODMAP. But when put together equates to a high amount of a single FODMAP. This can occur in a single recipe that contains multiple ingredients, or even in your meals and snacks throughout the day. This it is why it is vital to determine your own threshold for each of the FODMAPs in the challenge phase, so you know how much you can tolerate of each FODMAP.

Guide to Trialling Foods with an Unknown FODMAP Content

Just because a food has not been tested for FODMAPS, does not mean you have to avoid the food when on the low FODMAP diet. These foods can be trialled in a similar method to the challenge phase of the low FODMAP diet. It is important that you have already completed the elimination and challenge stages of the low FODMAP diet before trialling a food that has not been tested, to avoid adding any variables during these stages that could trigger your IBS symptoms. Follow the guide below when trying new foods:

  1. Ensure that you have been free of IBS symptoms for 5 days
  2. Make sure that you are consuming a low FODMAP diet before trialling a new food, to prevent another high FODMAP food from causing symptoms. Also be aware of fodstacking and try to avoid this when trying a new food.
  3. Start with a smaller amount of the food (¼ the usual serve size)
  4. The next day, trial a larger amount of the food  (½ the usual serve size)
  5. The next day trial a full amount of the food (1 usual serve size). Note: if you experience mild but manageable symptoms, have a 1 day ‘washout’ period between steps 4-6 to spread out your intake of the trial food.
  6. Trial the food in the diet for up to 1 week and document any symptoms experienced. Make sure to record the time you eat the new food, and the time when you experience symptoms. See the sample food and symptom diary below.
  7. Use these trials to determine how much of the food you can tolerate without experiencing uncomfortable symptoms (eg: ¼, ½ or 1 usual serve). This is based on the individual and what symptoms you find manageable. For example, you may experience slight bloating or flatulence, but this may be manageable unless it is causing pain or discomfort.
  8. Have a 3 day period between trials where you strictly follow the low FODMAP diet.
  9. If you become unwell, make sure to stop the trial with the food.
  10. Remember, not everyone will react the same to the foods that have not been tested.

Sample Test Schedule (Remember to only test 1 food at a time)

Example products Day 1 Test (1/4 usual serve) Day 2 Test (1/2 usual serve) Day 3 Test (1 usual serve)
Vegan Cornetto 15g (1/4 cornetto) 30g (1/2 cornetto) 60g (whole cornetto)
Sonoma Sourdough 12.5g (1/4 slice) 25g (1/2 slice) 50g (1 slice)
Wildly Good Sweet Potato and Kimchi Burger 62.5g (1/4 burger) 125g (1/2 burger) 250g (1 burger)
Arnold’s Farm Orange Cranberry & Cocoa Granola 15g (1/4 serve) 30g (1/2 serve) 60g (1 serve)

Sample Food and Symptom Diary

  Breakfast Morning Tea Lunch Afternoon Tea Dinner Dessert Stress / Anxiety (out of 10) Symptoms (bloating, nausea, pain, flatulence) Bowel Movements (frequency, constipation, diarrhoea)

Written by: Emily Monro (student dietitian)

Edited by: Rebecca Ponsford (APD)


  1. Erin Dwyer: https://www.monashfodmap.com/blog/3-phases-low-fodmap-diet/
  2. Erin Dwyer, Lyndal McNamara & Dr. Jane Varney: https://www.monashfodmap.com/blog/how-avoid-fodmap-stacking/
  3. K. Whelan, LD Martin, HM Staudacher, MCE Lomer: https://onlinelibrary.wiley.com/doi/full/10.1111/jhn.12530
10 Step Guide to Trialling Foods That Have Not Been Tested For FODMAPs in Your Low FODMAP Diet
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