Letter: Low FODMAP Therapy in Paediatric Irritable Bowel Syndrome: Balancing Efficacy, Expectancy and Safety. Authors' Reply

Dear Editor,

We thank Hakimi and Giles [1] for engaging with our study [2]. Their letter raises important questions about long‐term safety and implementation. We welcome the opportunity to clarify several aspects of our study design that may help place our findings in the appropriate clinical context.

First, expectancy effects are unlikely to fully account for the observed findings. In crossover dietary trials, each participant acts as their own control, which helps reduce between‐person variability and limits some forms of bias. More broadly, the methodological literature is clear that blinding in whole‐diet interventions is difficult, but still feasible only within practical limits, and that careful design, blinded outcome assessment, and transparent reporting represent appropriate standards rather than flaws [3]. Earlier paediatric randomised evidence also used a double‐blind crossover design to test low‐FODMAP exposure in children with IBS, showing that this general approach is both precedented and scientifically valid [4].

Second, the observed benefit cannot be entirely attributed to nonspecific dietetic attention alone. Prior randomised data in children showed that a low‐FODMAP diet reduced abdominal pain frequency compared with a typical childhood diet, supporting a diet‐specific effect rather than a purely contextual one [4]. In adults, response rates have also been consistently higher with low‐FODMAP intervention than with sham dietary advice, again indicating benefit beyond supportive contact alone [5]. At the same time, structured dietary care has real therapeutic value, which makes an active comparator clinically appropriate rather than conceptually problematic [3, 6].

Third, the biological signals observed in low‐FODMAP research argue against expectancy as the sole explanation for improvement. In children, baseline gut microbiome composition and predicted microbial metabolic capacity were associated with response to the low‐FODMAP diet, suggesting measurable biological heterogeneity in treatment effects [4]. In adults, faecal volatile organic compound profiles classified response to low‐FODMAP treatment with 97% mean accuracy and a 95% CI of 96%–99%, reinforcing the view that metabolic signatures track genuine physiological response rather than simple expectation [5].

Safety concerns deserve careful attention, especially in children, but they should be interpreted in proportion to the intervention actually studied. Reviews and society guidance agree that restrictive diets can carry risks related to nutritional adequacy and disordered eating, particularly when poorly implemented or self‐directed [7, 8]. That is exactly why paediatric guidance recommends that low‐FODMAP use, when considered, be limited in duration, used only in selected children, and delivered under the supervision of an experienced dietitian after attention to eating‐disorder risk and feeding difficulties [8]. Our interpretation is consistent with that evidence framework, not in conflict with it.

Finally, the call for larger studies, longer follow‐up, and better stratification tools is reasonable. But these are important research priorities for the field as a whole and do not detract from the interpretation of the present findings. The current literature already recognises both the promise of biomarker‐guided dietary therapy and the persistent methodological constraints of dietary trials, while emphasizing transparent reporting and ongoing safety evaluation [3, 4, 5].

Overall, we welcome this discussion and believe that our findings and the perspectives raised by Hakimi and Giles together contribute to a more balanced understanding of the role of the low‐FODMAP diet in paediatric IBS. Our study supports its short‐term efficacy under specialist supervision, while future research will further define which children benefit most and how this intervention can be implemented safely over time.

Author Contributions

Fernanda Cristofori: writing – review and editing. Vanessa Nadia Dargenio: writing – review and editing. Stefamia Paola Castellaneta: writing – review and editing. Ruggiero Francavilla: conceptualization, writing – original draft.

Funding

The authors have nothing to report.

Linked Articles

This article is linked to Cristofori et al. papers. To view these articles, visit https://doi.org/10.1111/apt.70830 and https://doi.org/10.1111/apt.70718.

Cristofori F., Dargenio V. N., Castellaneta S. P., and Francavilla R., “Letter: Low FODMAP Therapy in Paediatric Irritable Bowel Syndrome: Balancing Efficacy, Expectancy and Safety. Authors' Reply,” Alimentary Pharmacology & Therapeutics 64, no. 7 (2026): 1023–1024, 10.1111/apt.70866.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.