Functional gastrointestinal (GI) disorders affect an estimated 14% of children worldwide. Experts anticipate an increase in prevalence rates due to pandemic-related stress and anxiety.1 Such trends underscore the need for a range of effective treatment options for this patient population.

While numerous studies2 have shown that adult patients with functional GI disorders experience symptom relief by adhering to a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs), there is a dearth of evidence regarding the effectiveness of the low FODMAP diet (LFD) in children.

Several studies have aimed to close this gap by investigating the impact of the LFD and high-FODMAP intake on symptoms in pediatric patients with functional GI disorders. In 2019, a retrospective clinical case note review including 29 children aged 4 to 17 years with functional bowel disorders who were treated with an LFD was conducted. Symptom improvement was observed in 79% of patients, while complete symptom resolution was noted in 92% of patients with bloating, 87% of those with diarrhea, and 77% of those with abdominal pain.3


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In a study published in 2020, children aged 6 to 18 years with irritable bowel syndrome (IBS) were randomly assigned to an LFD group or a standard GI-protective diet group (n=30 in each group). Enrollees were advised to avoid caffeine, chocolate, acidic, spicy, and high-fat foods. At baseline, both groups were similar in terms of age, sex, symptom duration, and visual analog scale (VAS) scores reflecting symptom severity.4 After 2 months of the diet intervention, the LFD group showed a significant decrease in VAS scores compared with the standard group (3.80±1.10 vs 2.03±1.03). At 2 months following cessation of each diet (4 months after baseline), VAS scores showed a significant increase in the LFD group compared with the standard diet group (2.97±1.10 vs 1.63±0.71).4

In a randomized controlled trial published in 2020, children with functional abdominal pain (n=27) were assigned to a 4-week intervention consisting of an LFD or a control diet based on the National Institute for Health and Care Excellence (NICE) guidelines.5 Although the LFD group demonstrated a tendency toward symptom improvement, this change did not reach statistical significance, and no significant differences in stool consistency were found. In the NICE group, participants demonstrated significant reductions in abdominal pain intensity (per the Wong-Baker FACES Pain Rating Scale) and frequency (P <.01), as well as improvement in stool consistency (per the Bristol Stool Form Scale), with 93% reporting normal stool (P <.05).5

A 2021 study investigated the effects of FODMAP intake in 46 children with celiac disease (CD) compared against 46 children with nonceliac, mild chronic GI complaints and 46 healthy controls. According to the results, FODMAP intake was lower in the CD group compared with the other groups (P <.0001) but was not related to GI symptoms (P >.05).6 Study findings also revealed that an LFD was associated with lower health-related quality of life (HRQOL). Additionally, lower FODMAP intake from fruits and vegetables in particular was associated with reduced diet adequacy and quality in the CD group (both P <.05).6

The heterogeneity of results across these studies highlights the need for ongoing research to elucidate the potential role of the LFD in children with functional GI disorders.

For additional insights regarding this topic, we interviewed the following clinicians: Andrew S Day, MB, ChB, MD, FRACP, AGAF, professor of pediatrics at the University of Otago in Christchurch, New Zealand, and pediatric gastroenterologist at Christchurch Hospital; Stephanie Brown, a pediatric gastroenterology dietitian and PhD candidate at the University of Otago; and Alena Frankish, RD, a registered dietitian at the University of Alberta in Canada. Brown and Dr Day are coauthors of the 2019 retrospective case review supporting the effectiveness of the LFD in children, and Frankish is 1 of the authors of the 2021 study described above.3,6

What does the literature suggest thus far about the effectiveness of the LFD diet in children with GI disorders? 

Dr Day: In recent years we have gathered extensive experience in the use and application of the LFD in children, particularly those with functional GI disorders. We utilize the LFD regularly in the setting of functional GI disorders and in children with other GI conditions, such as Crohn disease, who have concurrent functional symptoms. 

In our report published in 2019, we showed that the LFD resulted in significant improvements, especially in children with symptoms of abdominal bloat or diarrhea. Children with abdominal pain also showed benefits. Foods containing fructans were the most common group contributing to symptoms, and apples were the single food most commonly reported by children.3

Moreover, it was common for children to be intolerant to more than 1 fermentable carbohydrate subgroup, such as lactose and fructans, for example.3 Lastly, our experience indicates that the success rate of the LFD in reducing symptoms of functional GI disorders in children is similar to the rate described with the use of the LFD in adults — up to 80% internationally.7

There are several other published reports showing the benefits of the LFD in children with functional GI disorders. The team led by Dr Bruno Chumpitazi at Baylor College of Medicine and Texas Children’s Hospital in Houston, has performed a number of clinical trials focused on the LFD and highlighted various aspects, including relationships between the intestine microbiome and response to the LFD.8 Some other investigators have focused more strictly on recurrent abdominal pain in childhood; the current data is mixed and preliminary in this group of children.9

Further studies are underway. One pilot study has looked at the use of the LFD in children with autism in regards to GI and behavioral symptoms. GI symptoms tended to improve, but no change in behavior was noted.10 Interestingly, some work has also focused on colic in breastfeeding infants. Maternal LFD resulted in improvement in colic symptoms in the infants.11 

Frankish: The research in this area remains limited and is somewhat controversial. Overall, the evidence on associations and effect is available and consensus exists that yes, reducing FODMAPs in the diet may help to significantly relieve GI symptoms in the population with functional GI disorders. However, it is important to recognize that the majority of research supporting the use of the LFD was done in the adult population. Pediatric studies are few and variations in age groups, interventions, and duration make them difficult to compare.

In our study, we were exploring potential benefits of the LFD for children with celiac disease and recurring functional GI complaints. The results showed no relation between FODMAP intake and GI symptoms in children; however, there was a positive association with HRQOL, diet adequacy, and overall diet quality, which are all very important determinants of health to consider in clinical practice.6

For patients who may benefit from this diet, what recommendations should clinicians give parents about reducing the burden (related to time and expense, etc) associated with adherence to the LFD?

Brown: Adopting an LFD involves numerous changes in food choices and selection. Given the potential benefits for children with relevant symptoms that are likely to respond, it is important to undertake the LFD carefully and rigorously. It is important to conduct an LFD under the guidance of an experienced and knowledgeable dietitian — while anyone can Google how to start an LFD independently, efficacy studies are based only on people who have worked with a specialized dietitian.

This will also help mitigate the potential for unnecessary over-restriction of foods that may impact adversely upon nutritional status and diet quality in the long term, especially in young children. Moreover, we want to prevent any harmful food behaviors such as disordered eating from developing in this impressionable age group.

Care during each of phase of dietary change is important. Full restrictions should be only for the prescribed time. Reintroduction should be conducted carefully with 1 group of foods at a time. This process may identify 1 or more food groups that trigger symptoms. Nontriggering foods should be reintroduced to habitual diet. Subsequent testing of thresholds of trigger foods is also encouraged, as these may change over time. ​For example, we advise that children retest their trigger sugar group every 3 months to determine if tolerance has changed. 

Frankish: Overall, an LFD doesn’t need to be expensive or time-consuming. The same tips that work for any other types of diets will work here as well: plan ahead, cook in batches and freeze, use a slow cooker, etc.

I believe one of the most important things is to let a patient know that there will be a follow-up and reintroduction of foods with an aim to further determine triggers — eg, types of FODMAPs — which will also help to avoid unnecessarily long-term restrictions. Although seemingly obvious, this is surprisingly often overlooked in practice. Being proactive and advocating the importance of a reintroduction phase to patients is very important, particularly to those who have significant improvement in symptoms, as they may be the most reluctant to add foods back.

For this reason, having a pediatric dietitian with expertise in GI disorders and the LFD as part of the care team can greatly assist, not only with the food reintroduction phase but also with the establishment of a long-term individualized meal plan. In our study, an LFD was associated with overall low diet quality.6 Following this diet removes or minimizes a ton of nutritious foods that are important for children. Therefore, we caution clinicians against overusing it, as the risk of associated nutritional deficiencies (and reduced HRQOL) is likely high. That’s why, if deciding to recommend an LFD, referral to a dietitian for further support is essential

What should clinicians and parents do to minimize the risk that these patients may develop disordered eating from being on a restrictive diet?

Brown: It is important that patients and families adhere to prescribed durations and guidelines for the use of the LFD and work with a dietitian with specialist knowledge in this area to prevent unnecessary over-restriction of foods. Careful monitoring is essential at each phase of the LFD.

Moreover, our 2019 study showed that 25% of children were experiencing concurrent mental health disorders — especially anxiety.3 Identifying comorbid factors such as anxiety and considering appropriate referral to relevant psychology support services is an important component of the child’s overall care.

If current or historical clinical “red flags” around disordered eating are noted prior to commencing the LFD, it would not be recommended for this child to commence the diet. 

Frankish: As we know, any type of restrictive diet can place children at higher risk for developing various food aversions and disordered eating later in life. This is one of the main reasons why an LFD is usually not recommended for children who are already diagnosed with disordered eating, eating disorders, and selective or severe picky eating.

When we focus on improving immediate physical symptoms, potential long-term complications and mental health aspects are easily overlooked. Therefore, discussing risks and strategies with families and enhancing care by involving interprofessional team members right from the beginning is essential.

Some great general points to include in conversation are: “A low FODMAP diet doesn’t mean a no FODMAP diet,” and “Avoid referring to foods as ‘good for you’ or ‘bad for you.’” Overall, I often recommend that parents shift the focus from foods that need to be avoided to the variety of delicious and nutritious food that can be offered.

What should be the focus of future research regarding the LFD in children with GI disorders?

Dr Day: Although we know a lot about the use of the LFD from many studies conducted in adult populations, we are still learning about the use of this intervention in children and adolescents. Reports over the last few years have resulted in new information and understanding about the use of the LFD in children. However, there continue to be many areas that require more research to ensure that this intervention is considered more widely and used wisely across the world.

Some of the areas that require further attention are:

  • Additional studies focusing on the role of the LFD in functional GI disorders in children
  • Establishing better ways to identify the children who might respond better to the LFD
  • Evaluating and understanding the impact of altered FODMAP intake upon the developing microbiome when used early in life
  • Considering the potential impact of the LFD upon the microbiome in the short and longer term 
  • Development and use of specific internationally-recognized pediatric resources that might help to standardize care

Frankish: Much more research is definitely needed in this area, as an increasing number of children report experiencing chronic GI pain. The LFD has already shown some promising results in adults and is rapidly gaining popularity. However, this is perhaps a pivotal point for clinicians to remember: We need to avoid the temptation to apply these findings to children, who have different physiological and psychological needs for growth and development.

We need more high-quality research to determine effective and sustainable therapeutic strategies to resolve ongoing GI symptoms in children with and without other health conditions. A lot of previous research was focused on 1 or 2 FODMAPs only, so studies that would analyze all FODMAPs are really needed. We also need studies that would be specific and include children of certain age groups (for example, teens vs toddlers) and different socioeconomic and cultural backgrounds, and most importantly, research that would investigate potential risks and long-term implications for growth and development of children.

References

  1. Di Lorenzo C. Pandemic stress may lead to, exacerbate functional GI disorders in children. American Academy of Pediatrics News. September 1, 2021. Accessed February 21, 2022. https://publications.aap.org/aapnews/news/15555
  2. Wang J, Yang P, Zhang L, Hou X. A low-FODMAP diet improves the global symptoms and bowel habits of adult IBS patients: a systematic review and meta-analysis. Front Nutr. Published online August 19, 2021. doi:10.3389/fnut.2021.683191
  3. Brown SC, Whelan K, Gearry RB, Day AS. Low FODMAP diet in children and adolescents with functional bowel disorder: a clinical case note review. JGH Open. 2019;4(2):153-159. doi:10.1002/jgh3.12231
  4. Dogan G, Yavuz S, Aslantas H, Ozyurt BC, Kasirga E. Is low FODMAP diet effective in children with irritable bowel syndrome?. North Clin Istanb. 2020;7(5):433-437. doi:10.14744/nci.2020.40326
  5. Boradyn KM, Przybyłowicz KE, Jarocka-Cyrta E. Low FODMAP diet is not effective in children with functional abdominal pain: a randomized controlled trial. Ann Nutr Metab. 2020;76(5):334-344. doi:10.1159/000510795
  6. Cyrkot S, Marcon M, Brill H, et al. FODMAP intake in children with coeliac disease influences diet quality and health-related quality of life and has no impact on gastrointestinal symptoms. Int J Food Sci Nutr. 2021;72(7):956-967. doi:10.1080/09637486.2021.1880553
  7. O’Brien L, Skidmore P, Wall C, et al. A low FODMAP diet is nutritionally adequate and therapeutically efficacious in community dwelling older adults with chronic diarrhoea. Nutrients. 2020;12(10):3002. doi:10.3390/nu12103002
  8. Chumpitazi BP, Cope JL, Hollister EB, et al. Randomised clinical trial: gut microbiome biomarkers are associated with clinical response to a low FODMAP diet in children with the irritable bowel syndrome. Aliment Pharmacol Ther. 2015;42(4):418-27. doi:10.1111/apt.13286 
  9. Stróżyk A, Horvath A, Muir J, Szajewska H. Effect of a low-FODMAP diet for the management of functional abdominal pain disorders in children: a study protocol for a randomized controlled trial. Nutr J. 2021;20(1):1. doi:10.1186/s12937-020-00656-3
  10. Nogay NH, Walton J, Roberts KM, Nahikian-Nelms M, Witwer AN. The effect of the low FODMAP diet on gastrointestinal symptoms, behavioral problems and nutrient intake in children with autism spectrum disorder: a randomized controlled pilot trial. J Autism Dev Disord. 2021;51(8):2800-2811. doi:10.1007/s10803-020-04717-8
  11. Iacovou M, Craig SS, Yelland GW, Barrett JS, Gibson PR, Muir JG. Randomised clinical trial: reducing the intake of dietary FODMAPs of breastfeeding mothers is associated with a greater improvement of the symptoms of infantile colic than for a typical diet. Aliment Pharmacol Ther. 2018;48(10):1061-1073. doi:10.1111/apt.15007