top of page


FODMAP testing is best done using a food approach. 


Breath tests for lactose and fructose have been popular in the past but recent research shows that fructose tests are inconsistent and unreliable, and lactose tests may indicate lactose is being malabsorbed but not whether you have lactose intolerance! That means, many people can have a degree of malabsorption but that does not mean that there is enough of an issue to cause symptoms.


Many people feel so relieved by the improvement of symptoms, especially if they have been suffering with intolerable symptoms for a long time with no answers in sight, that a desire to stay in the happy space of minimal symptoms is more than tempting. This is understandable.

The next phase, though is pretty exciting, as you get to IDENTIFY your specific food triggers. Everybody likes this stage, and often the results are quite surprising and liberating. Maybe you can tolerate the dreaded onion, but garlic is ok for you in moderate amounts. Maybe fructose is ok after all but it is sorbitol that sends your gut into spasms.

Until you do food trials, everything is just a 'best guess'. Food trials give a whole lot more clarity, and they are EASY trials.


The purpose of this diet is to give you personal knowledge about your triggers so you can decide if eating something is worth it to you or not. When you can identify most of your slip up triggers then you can be a lot more in control and less 'food anxious'.  

FACT: Many FODMAPs provide important food for our gut loving microbes. Foods that promote healthy bacteria in our gut are called prebiotics. FODMAPs are prebiotics.


For this reason, avoiding FODMAP triggers that you ultimately don't need to will help your gut.  Find out more about FODMAPs for our gut health.


Chances are that you are not sensitive to ALL the FODMAP foods- just SOME. The challenge program allows you to identify which of the FODMAPs are your personal triggers, and an idea of how sensitive you are: mild, moderate or very sensitive.

There are 8 -10 different challenges and the order of the challenges depends on your preferences (see below).

The challenges are simple  as they involve trialling out one food  (per FODMAP sub-group) at increasing doses over 3 days. These 3 days can be consecutive (at their fastest implementation), in the case of the smallest FODMAPs (lactose, excess fructose and the 2 polyols: sorbitol and mannitol)  or with a rest day in between each dose for the larger FODMAPs (GOS in legumes, and the fructans in bread, fruits, onion and garlic). The larger FODMAPs are best done with a day between doses as it takes longer for these FODMAPs to reach the large intestine where rapid fermentation occurs and symptoms are triggered.


Then 3 days of rest (and settled symptoms) before embarking on a new food trial.

At the end of the challenges- you will have a reaction profile and now can identify the high FODMAP foods causing you mild issues, moderate symptoms and more severe symptoms. Of course, you will also be identifying the FODMAPs that you have gone through all the effort of avoiding but end up being fine for you! The results never cease to surprise people who think they know what they are going to react to.


First up- these trials are really easy. Eat what you normally eat and just add the one food at one sitting into what you normally have. NO SPECIAL MEALS NEED TO BE MADE. In fact, best if this is not done as best not do anything too different to what you normally would do.

For example, for the excess fructose trial, you start of day 1 adding moderate dose of honey into (for example) your normal breakfast or just eating it on a spoon. That is it!! Really simple.


Food trials (or challenges) are commenced in any preferred order but fructose and lactose are often first as they are the most basic challenges. 


The smaller FODMAPs (fructose, lactose and the polyols) are the fastest trials as they can be over within 3 days followed by at least 3 days of rest (need to have a well settled gut before starting a new challenge). However, they don't have to be done on 3 consecutive days- you can just fit it into your busy lifestyle with days between, if needed.

The larger FODMAPs (Fructans: wheat, fruit, onion, garlic and GOS/galactans: ie legumes/almonds/soy bean milk) are best done with a day in-between followed by 3 days of rest. This is because we need to give time for the fructans or GOS/galactans to have time to reach the large intestine, and is best to see the impact of a small/medium or large dose before going onto the next dose.


  • Excess Fructose ( eg honey/mango)

  • Lactose (normal milk/ice cream)- only do if lactose was reduced in your Low FODMAP diet

  • Polyol: Sorbitol (eg apricot/avocado)

  • Polyol: Mannitol (eg cauliflower/mushroom)

  • Fructans: Wheat  (eg bread/ pasta)

  • Fructans: Onion & garlic 

  • Fructans: Fruit (eg grapefruit/raisins)

  • GOS/Galactans: Beans  (eg legumes/chickpeas/almonds)

Once the results of these trials are through then there are some combination trials, for example apples and pears have sorbitol and fructose FODMAPs so if you end up being fine with the fructose and sorbitol trials then checking the foods that have this combination can be a useful thing to do.

See upcoming blog on HACKS for doing FODMAP food trials.


Now is the time to get some FODMAP foods back into your diet - the best way to keep your gut as healthy as possible as FODMAPs are probiotics that help optimise your gut biome or natural probiotics in your gut.


This last phase of the FODMAP elimination diet, reintroduction, is based on what you have identified through food trials - which FODMAPs are fine for you, and which ones you may need to manage.

Foods that are fine can be reintroduced and check that you are actually fine with this, while the FODMAPs you react to can be reintroduced based on your individual level of sensitivity.


Read more about this in an upcoming page dedicated to reintroductions. 


Yao, C. K., and Tuck, C. J. (2017) The clinical value of breath hydrogen testing. Journal of Gastroenterology and Hepatology, 32: 20–22. doi: 10.1111/jgh.13689.

Gibson, P. R. (2017) The evidence base for efficacy of the low FODMAP diet in irritable bowel syndrome: is it ready for prime time as a first-line therapy?. Journal of Gastroenterology and Hepatology, 32: 32–35. doi: 10.1111/jgh.13693.

Barrett, J. S. (2017) How to institute the low-FODMAP diet. Journal of Gastroenterology and Hepatology, 32: 8–10. doi: 

Tuck, C., and Barrett, J. (2017) Re-challenging FODMAPs: the low FODMAP diet phase two. Journal of Gastroenterology and Hepatology, 32: 11–15. doi: 10.1111/jgh.13687.

bottom of page