Children & The Low FODMAP Diet

Children & The Low FODMAP Diet

Written by Sarah George APD, Hawthorn Health & Dietetics

Do you have a child struggling with constipation, diarrhoea, abdominal pain or bloating? A quick Google search will come up with a myriad of causes, but which one is right? Who do you trust? With so much confusing and conflicting information out there it can be difficult to determine what to do or how to proceed in order to help them.

It can be tempting to simply eliminate foods from your child’s diet, assuming they are “gluten intolerant” or “lactose intolerant” or “dairy intolerant”, or any other number of things, before getting professional advice. The problem here is that if your child’s symptoms haven’t been properly investigated you are putting your child at risk of nutritional deficiencies, growth concerns, and potentially serious complications of undiagnosed disease.

There are many causes of gastrointestinal upset in children, far too many to list here, but a common one I see in my clinic is due to FODMAPs.


FODMAPs stands for…


Oligo-saccharides (e.g. Fructans and Galacto-oligosaccharides)

Di-saccharides (e.g. Lactose)

Mono-saccharides (e.g. Excess Fructose)


Polyols (e.g. Mannitol and Sorbitol)

Simply put, FODMAPs are a group of short-chain carbohydrates (sugars) found naturally in many foods, which in some people are poorly absorbed by the small intestine. They continue down the digestive tract into the large intestine (gut) where they are fermented (broken down) by gut bacteria. This can result in a variety of gut symptoms such as diarrhoea, constipation, bloating, and abdominal pain.


Whilst not an exhaustive list, here are some of the more common sources of FODMAPs:

* Excess fructose found in honey, mango, and apples

* Fructans found in garlic, onion and wheat

* Lactose found in yoghurt, milk, and ice-cream

* Galacto-oligosaccharides found in legumes

* Polyols found in stone fruits, apples, pears, and some mushrooms


The low FODMAP diet aims to identify and limit foods that are not well tolerated, but only to the extent that is necessary to avoid triggering symptoms.

There are three stages to the low FODMAP diet.

1. “Low FODMAP diet” Phase

The first phase of the low FODMAP diet involves limiting the consumption of high FODMAP foods. There are different approaches that can be taken during this phase, and your dietitian will pick the most appropriate approach for your child’s situation.

Usually, it is not recommended for a child to follow a “strict” low FODMAP diet whereby moderate-high amounts of all of the FODMAP sub-groups are limited. Rather, it may be recommended your child follow a “simplified” low FODMAP diet, whereby only frequently consumed foods which are high in FODMAP sub-groups are limited.

This phase is intended to be short-term and temporary, lasting only 2-8 weeks (unless under the guidance of a dietitian or under advice from your medical doctor), and is not intended as a long-term solution.

Being on this first “low FODMAP” phase for longer than necessary can impact on your child’s quality of life and can make social engagements such as a meal out with the family extremely challenging. Restrictive diets in children can also have very real negative consequences such as nutritional inadequacy resulting in vitamin and/or mineral deficiencies and poor growth. In addition, the low FODMAP diet is low in prebiotic fibre which feeds our healthy gut bacteria, helping them to grow and flourish. Therefore, to avoid any potential negative changes in your child’s gut microbiome it is important to move through the first “low FODMAP” phase as quickly as possible.

2. “Re-Challenge” Phase

This phase involves systematically challenging FODMAPs to test your child’s tolerance to not only the types of FODMAPs but also the portion sizes they can tolerate before symptoms are triggered.

3. “Adapted FODMAP diet”

This is the long-term, maintenance phase, which only restricts FODMAP sub-groups and foods found to be poorly tolerated, and only to the extent necessary. It is during this stage where you can start to liberalise your child’s diet, reintroducing those

FODMAP groups that were well-tolerated whilst still maintaining adequate symptom control.


It is recommended that children are only placed on a low FODMAP diet if they have been diagnosed with Irritable Bowel Syndrome (IBS) by a doctor or gastroenterologist.

The low FODMAP diet has been scientifically proven to alleviate symptoms of IBS (1). Whilst the use of the low FODMAP diet in children is a fairly new concept, some initial studies have confirmed its effectiveness for children suffering with IBS (2-4). However, there are many factors that may contribute to gastrointestinal discomfort in children. So how do you know if your child truly has IBS?


There is no medical test which can diagnose IBS. This is because IBS occurs in the absence of any abnormal blood tests, doesn’t cause any physical damage to the gastrointestinal tract, and doesn’t involve the immune system – meaning it won’t show up on any allergy testing. Therefore, IBS is diagnosed according to symptom presentation after all other relevant medical conditions have been tested for and excluded. Diagnosis should only be made by your doctor or gastroenterologist.

The ‘Rome IV Diagnostic Criteria’ is used to guide diagnosis of IBS. In short, it states that children should feel abdominal pain for at least 4 days per month, with the pain being associated with a change in frequency and/or appearance of stool, and/or pain related to defecation (5). These symptoms should not be able to be explained by any other medical condition.

IBS in children is characterised by chronic gastrointestinal symptoms which include one or more of the following (6):

* abdominal pain

* bloating or visible abdominal distension

* diarrhoea, with or without urgency, with or without nappy rash

* constipation, with or without feelings of incomplete evacuation, with or without soiling

* excessive wind

As adults, it is fairly easy to provide accurate descriptions of any symptoms we may be experiencing. It is trickier identifying these IBS symptoms in young children who are non-verbal or not yet able to fully articulate themselves. In toddlers and pre-school aged children, some signs to look out for include issues with toilet training, unformed bowel actions continuing past infancy, behaviour changes or irritability, sleep disturbances, and anxiety (6). In school-aged children and adolescents, IBS symptoms may manifest as children missing school, withdrawing from social activities to avoid embarrassment amongst peers, spending a longer than normal time on the toilet, or depression (6).

A note on breath testing and fructose malabsorption

When FODMAPs are fermented by gut bacteria they produce either methane and/or hydrogen gas which is then absorbed into the blood, travels to the lungs, and is then breathed out (7). Breath tests work by measuring the amount of gas produced to determine whether someone ‘malabsorbs’ a particular FODMAP sub-group or not.

In young children the testing process can be compromised due to their inability to blow into the testing bag adequately, or to consume the recommended FODMAP dose required for testing. That being said, the only breath test with any real clinical significance is the lactose breath test when used to confirm or deny lactose malabsorption (6).

The fructose breath test is less reliable. Studies have shown that children under the age of 10 years have a natural reduced capacity to absorb fructose (8-9). So fructose breath testing in this age group is clearly problematic and raises questions about the validity of positive test results. If your child has received a diagnosis of “fructose malabsorption” based on a breath test result it is important to see a dietitian who can guide you further as to the validity of this diagnosis and treatment moving forward.

The Monash University FODMAP team refer to “fructose malabsorption” as a “pseudo-diagnosis”. A diagnosis of “fructose malabsorption” is not helpful to parents with young children as it indicates there is a problem, when in fact symptoms may be occurring due to this natural phenomenon which can improve with age. Additionally, in some cases it may be necessary to moderate intake of other FODMAPs in addition to fructose, and so “fructose malabsorption” doesn’t fit the full clinical picture. Monash University urges the importance of not labelling these children as having “fructose malabsorption” but instead they should be informed their symptoms are due to IBS and are being triggered by certain foods (6).


While there are some suggested mechanisms, unfortunately, we just don’t know the exact cause. We do know that children who have a parent with IBS and/or chronic pain are at an increased risk of developing IBS in childhood (6). There is also evidence showing that a bout of gastroenteritis can potentially alter the amount and type of bacteria in the gut, resulting in ‘post-infectious IBS’ (10). Other research suggests that diagnosed cow’s milk allergy in infants is a risk factor for the development of IBS in children (6).


1. Discuss your child’s symptoms with your doctor, paediatrician or paediatric gastroenterologist

It is extremely important that you have discussed your child’s symptoms with your doctor or specialist. There are many causes of gastrointestinal discomfort in children which present with similar symptoms to IBS. These include Coeliac Disease, Inflammatory Bowel Disease, non IgE-mediated food allergies, food intolerance, other functional gastrointestinal disorders, infections and malignancies. Therefore, it’s essential your child has undergone the appropriate testing for these PRIOR to making any dietary changes. An incorrect diagnosis can lead to ineffective treatment and disease complications, so it is essential your child’s symptoms are thoroughly assessed and all necessary exclusionary tests are performed to confirm the diagnosis of IBS.

If your child is experiencing persistent or progressive anaemia, nocturnal bowel motions, night waking, unexplained weight loss or poor growth, joint pain, chest pain, pain with urination, or difficulty swallowing, you should present to your medical team for further investigation. These are not typical IBS symptoms and warrant further investigation (6). Likewise, recurrent vomiting, rectal bleeding, or a family history of coeliac disease or inflammatory bowel disease, all require further investigation by your medical doctor before a diagnosis of IBS is made (6,11).

2. Make an appointment with a Dietitian

Once your child’s IBS has been diagnosed, it is time to make an appointment with a dietitian trained in paediatric nutrition and FODMAPs. You might think you can “go it alone” with the amount of information freely available on the internet, but the accuracy of many of these resources is often questionable. An appointment with a dietitian may very well save you time, energy, and money in the long run.

A FODMAP trained paediatric dietitian will be able to provide a thorough initial assessment of your child, verifying your child’s symptoms against the Rome IV criteria, and ensure appropriate medical investigations have been performed to exclude other diagnoses. A dietitian will consider other factors which can affect bowel symptoms, such as fluid and fibre intake, and physical activity levels. A “strict” low FODMAP diet approach is not always indicated as the primary line of treatment, and a dietitian will guide you as to what kind of dietary changes are necessary. Most importantly, your dietitian can help to ensure your child’s diet remains nutritionally adequate.

Children have specific nutrition needs, and restrictive diets can lead to nutritional deficiencies impacting on normal growth and development. Of particular concern are iron, calcium and fibre (6). Therefore, it is extremely important the low FODMAP diet is not undertaken without medical advice and the guidance of a dietitian.


You cannot and should not self-diagnose your child as having IBS. Given the overlapping symptoms between IBS and other diseases, it is imperative to see your medical doctor or specialist to obtain the correct diagnosis. Furthermore, removing foods from your child’s diet may impact on the validity of testing for certain diseases like coeliac disease, further prolonging and delaying the correct diagnosis.

Seeing your doctor and/or specialist is essential for diagnosis, and an appointment and assessment by a dietitian should not be underestimated. Unfortunately, not everything that needs to be covered can be covered during one appointment with a dietitian, so be prepared for multiple visits if needed, and come armed with plenty of questions.

I love working with families to help them get to the bottom of their child’s symptoms. The journey can be long and complex, but it’s extremely satisfying to see their child’s symptoms improve as a direct result of my help and guidance.

Sarah is a dietitian who works with both children and adults with food intolerances and IBS. She practices in Melbourne, Australia but provides Skype consultations worldwide. She also helps facilitate an online Facebook group called “Low FODMAP Parent Support” which you are welcome to join for more guidance and support, but please note this group does not replace medical advice and should not be used as a substitute for working with your own dietitian.


1. Halmos EP, et al, ‘A Diet Low in FODMAPs Reduces Symptoms of Irritable Bowel Syndrome’, Gastroenterology 2014;146(1):67-75.

2. Gomara RE, et al, ‘Fructose intolerance in children presenting with abdominal pain’, J Pediatr Gastroenterol Nutr 2008;47(3):303-8.

3. Escobar MA Jr, et al, ‘Fructose intolerance/malabsorption and recurrent abdominal pain in children’, J Pediatr Gastroenterol Nutr 2014;58(4):498-501.

4. Wintermeyer P, et al, ‘Fructose malabsorption in children with recurrent abdominal pain: positive effects of dietary treatment’, Klin Padiatr 2012;224(1):17-21.

5. Hyams S, et al, ‘Childhood Functional Gastrointestinal Disorders: Child/Adolescent’, Gastroenterology 2016;150:1456-1468.

6. Monash University, ‘Low FODMAP Dietitian Course 2018’.

7. Gastrolab, ‘Hydrogen and Methane Breath Testing for Gastrointestinal Disorders’,

8. Dabritz J, et al, ‘Significance of hydrogen breath tests in children with suspected carbohydrate malabsorption’, BMC Pediatr 2014;14:59.

9. Jones HF, et al, ‘Effect of age on fructose malabsorption in children presenting with gastrointestinal symptoms’, J Pediatr Gastroenterol Nutr 2011;52(5):581-4.

10. Monash University, ‘Frequently Asked Questions about FODMAP’,

11. International Foundation for Gastrointestinal Disorders, ‘Bellyaches in Children’,


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  • Jennie

    Great information Sarah. Thank you.

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