The scale of the problem is growing. Pediatric-onset inflammatory bowel disease is rising in incidence worldwide, and children tend to carry a more aggressive disease phenotype than adults, facing decades of potential inflammation, hospitalization and surgery. Biologic agents such as infliximab and adalimumab have transformed outcomes, but long-term cohort data show that a substantial fraction of children lose response over time, and drug approval pathways for young patients remain constrained. Against this backdrop, nutritional therapy occupies a unique position: it is the only induction strategy recommended by European guidelines as first-line for pediatric Crohn’s disease that simultaneously improves inflammation, supports growth and avoids pharmacological side effects. The catch, as the review emphasizes, is that remission rates vary considerably across studies depending on research design, treatment population and how remission is defined in the first place.

The authors frame the field’s central challenge as a transition away from a one-treatment-suits-all strategy toward a tailor-made, precision-based approach. In principle, a clinician armed with a reliable treatment-responsiveness phenotype could match each child to the therapy most likely to work before the first formula feed or the first injection. The benefits would cascade through the healthcare system: fewer months spent on ineffective regimens, less exposure to unnecessary immunosuppression, earlier escalation for the children who need it, and reduced lifetime costs of a disease whose economic burden is among the highest of any chronic inflammatory condition. The obstacle is that, despite decades of research, the evidence base for definitive predictors of response to nutritional therapy remains insufficient, a conclusion the review states plainly rather than glossing over.

What does the existing evidence actually suggest? Among the most consistently reported signals are early clinical improvement and a reduction in faecal calprotectin, the stool-based marker of intestinal inflammation that has become a workhorse of pediatric IBD monitoring. Serial measurements during exclusive enteral nutrition have been shown to track with disease activity and treatment response, and falling calprotectin concentrations during therapy have been linked to better outcomes and to the prediction of clinical relapse after treatment ends. Early mucosal healing, visible at endoscopy in newly diagnosed children, is also associated with improved long-term outcomes. But the picture is not clean: at least one prospective pediatric study concluded that faecal calprotectin is not a clinically useful marker for predicting early non-response to exclusive enteral nutrition, and the review notes that the rapid fall in calprotectin seen during treatment is lost quickly once food is reintroduced. Timing, it seems, matters as much as the marker itself.

Disease location offers another thread of evidence, though a tangled one. Classic work from the early 2000s suggested that colonic Crohn’s disease without ileal involvement responds less well to enteral nutrition, hinting that the intestinal segment where inflammation resides shapes the therapy’s effectiveness. Later studies complicated this view, with some reporting that disease phenotype does not influence clinical remission at all, and others examining whether specific scoring systems can predict short- and long-term mucosal healing across different gastrointestinal segments. The review also highlights practical determinants that have nothing to do with biology: adherence. Real-world studies of children starting exclusive enteral nutrition have identified factors associated with higher adherence and better response, and parent-perspective research underscores how difficult the diet’s social and psychological demands can be for families. Whether the formula is polymeric or elemental, and whether it is delivered orally or by tube, appears to have little effect on outcomes, which at least simplifies one clinical decision.

The most scientifically vibrant frontier, and the one the review treats as the field’s future horizon, lies in the gut microbiome. Nutritional therapy works, at least in part, by reshaping the microbial communities that drive intestinal inflammation, and several prospective studies have now reported microbial signatures that predict response. Children whose baseline gut communities contain particular bacterial taxa and functional profiles have been shown more likely to achieve sustained remission after exclusive enteral nutrition, and early shifts in microbial community structure during treatment have been associated with durable remission. Metabolomic analyses add another layer, with gut metabolome signatures alongside microbiota profiles predicting response in prospective pediatric cohorts. Even a child’s pre-diagnosis diet has been found to correlate with the microbiome and to predict response to enteral nutrition, suggesting that long-term dietary habits may prime the gut environment for success or failure before therapy even begins.

These findings align with a broader conceptual shift captured in a 2024 position paper from the European Society for Paediatric Gastroenterology, Hepatology and Nutrition, which called for precision nutrition in pediatric IBD. The logic is compelling: if exclusive enteral nutrition remodels the microbiome and its metabolic output, then the composition of a child’s starting microbial community should, in theory, determine how far that remodeling can go. Multidisciplinary consensus work on microbiome-based biomarkers published in The Lancet Microbe has begun to define the standards such biomarkers would need to meet before clinical deployment, and the review argues that integrating clinical data with multiomic information, spanning genomics, microbiomics and metabolomics, into a unified decision-making framework could eventually enable genuinely personalized treatment selection. Machine learning approaches developed for targeted therapies elsewhere in medicine offer a template for how such heterogeneous data streams might be combined.

The authors are careful, however, to temper enthusiasm with rigor. Anticipating treatment response, they write, transcends simple stratification based on clinical characteristics, meaning that no checklist of age, disease location, severity or laboratory values currently suffices to forecast outcome. The literature they surveyed provides insufficient evidence for definitive predictors, and many of the most promising microbiome and metabolome studies are small, single-center and retrospective, vulnerable to the confounding and overfitting that plague biomarker research. The path forward, they suggest, involves prospective validation of candidate predictors in large, well-phenotyped cohorts, harmonized definitions of remission and response, and ultimately the kind of integration of clinical and multiomic data that precision medicine initiatives in other fields have begun to demonstrate at scale.

For families facing a new diagnosis, the practical message of the review is one of cautious optimism. Nutritional therapy remains a first-line, evidence-based option, whether as exclusive enteral nutrition or as partial enteral nutrition combined with the Crohn’s disease exclusion diet, and randomized trial evidence shows the dietary approach can induce rapid, sustained remission in children. Early clinical improvement and falling faecal calprotectin during the first weeks of treatment are reasonable indicators that the therapy is working, and clinicians can use them to guide decisions about continuing or switching. What the field cannot yet do is predict, before the first sip of formula, which child will respond. Closing that gap, the review concludes, may be a small but crucial step toward individualized therapy for every child with Crohn’s disease, transforming a treatment that sometimes works brilliantly into one that works brilliantly for the right patients, chosen in advance.

Subject of Research: Predictors of response to nutritional therapy in pediatric Crohn's disease

Article Title: Current perspectives and future horizons in predicting response to nutrition therapy in children with Crohn’s disease – a narrative review

Article References: Krawiec, P., & de Ridder, L. (2026). Current perspectives and future horizons in predicting response to nutrition therapy in children with Crohn’s disease – a narrative review. Pediatric Research. https://doi.org/10.1038/s41390-026-05559-3

Image Credits: AI Generated

DOI: 10.1038/s41390-026-05559-3

Keywords: Crohn's disease, exclusive enteral nutrition, pediatric IBD, precision nutrition, faecal calprotectin, gut microbiome, Crohn's disease exclusion diet, personalized medicine, multiomics, biomarkers, mucosal healing, narrative review

Colitis, a form of inflammatory bowel disease characterized by chronic inflammation of the colon, poses significant treatment challenges and impacts millions globally. Traditional therapeutic strategies mainly involve immunosuppression and symptomatic relief but fall short of addressing the underlying mechanisms governing mucosal repair and homeostasis. The current study shifts the focus towards endogenous metabolic regulators influenced by resident microbiota, showing how microbial metabolites can modulate host metabolism to promote intestinal healing.

Indole propionic acid is a lesser-known yet biologically potent bacterial metabolite produced primarily by specific gut commensals. Researchers have long hypothesized the involvement of such small molecules in signaling cascades between microbiota and host tissues. This latest work elucidates how IPA specifically regulates the expression and activity of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), a key mitochondrial enzyme driving ketogenesis within intestinal epithelial cells.

Ketogenesis, traditionally associated with hepatic metabolism during fasting states, has recently been recognized for its extrapolation to other tissues, including the gut. Within the intestinal epithelium, ketone bodies act not only as alternative energy substrates but also as signaling molecules influencing inflammation and cellular repair. By enhancing HMGCS2 activity, IPA effectively stimulates ketogenesis, thereby fostering an environment conducive to mucosal regeneration and barrier integrity restoration.

The molecular underpinnings of this pathway involve IPA binding events that alter transcriptional networks within intestinal epithelial cells, leading to upregulated HMGCS2 gene expression. These changes underpin augmented ketone body synthesis, which subsequently exerts anti-inflammatory effects, dampening pathological immune responses inherent in colitis. Consequently, the interplay between microbial metabolites and host metabolic enzymes emerges as a critical determinant of therapeutic outcomes in intestinal inflammation.

In experimental models of colitis, administration of IPA or modulation of gut microbiota composition yielded robust protection against colonic inflammation. Mice treated with IPA demonstrated significant reductions in disease severity, histological damage, and pro-inflammatory cytokine release. These protective effects correlated with enhanced mucosal healing, underscoring the therapeutic potential of targeting microbiota-derived metabolites and their metabolic pathways.

Beyond preclinical models, the study hints at translational implications for human IBD. Analysis of patient samples revealed a consistent decrease in intestinal HMGCS2 expression and ketone body levels during active disease phases, suggesting that impaired microbiota-host metabolic crosstalk contributes to disease progression. Restoring this axis through probiotic or metabolite-based therapies holds promise for more effective and durable interventions against colitis.

Additionally, the research offers insights into the spatial and temporal regulation of gut ketogenesis, emphasizing the role of localized metabolic shifts in orchestrating immune tolerance and barrier function. Intestinal epithelial cells serve as dynamic metabolic hubs capable of sensing microbial signals and adapting their metabolic programs accordingly, a concept that challenges traditional views of tissue metabolism in health and disease.

Mechanistically, the IPA-HMGCS2 pathway integrates with broader metabolic networks involving fatty acid oxidation, mitochondrial biogenesis, and reactive oxygen species management. This integration highlights the multifaceted nature of metabolic regulation within the gut epithelium and its centrality in maintaining mucosal resilience under inflammatory stress.

Furthermore, these findings underscore the critical influence of microbiota composition on host metabolic health, reinforcing the need to consider microbial ecology in disease pathogenesis and treatment. Dysbiosis, characterized by the loss of IPA-producing bacteria, may predispose individuals to heightened susceptibility to colitis by disrupting this protective ketogenesis-driven mechanism.

The discovery also paves the way for novel biomarker development, where circulating or fecal IPA levels could serve as indicators of mucosal health and therapeutic response. Monitoring these metabolites might refine patient stratification and individualized treatment approaches in clinical practice.

Crucially, this study advocates for a paradigm shift towards leveraging host-microbiota metabolic synergies as a frontier in biomedical innovation. Targeting metabolic nodes like HMGCS2 via microbiota-derived compounds holds transformative potential beyond colitis, possibly extending to other inflammatory and metabolic disorders.

Moreover, the implications of this research reach into nutritional sciences, where diet-induced modulation of microbiota composition and metabolite production could complement pharmacological strategies. Nutritional interventions designed to boost IPA levels or sustain HMGCS2 activity might represent adjunctive therapies enhancing mucosal healing and disease remission.

In conclusion, the intricate crosstalk unveiled between microbiota-derived IPA and intestinal ketogenesis via HMGCS2 not only redefines our understanding of mucosal immunometabolism but also heralds a new era of microbiome-centric therapeutics for colitis. As research unfolds, harnessing these endogenous metabolic circuits promises more precise, effective, and lasting interventions for patients burdened by inflammatory bowel diseases.

Subject of Research: The interaction between microbiota-derived indole propionic acid (IPA) and the regulation of intestinal ketogenesis mediated by HMGCS2 in the context of colitis and mucosal healing.

Article Title: Microbiota-derived IPA protects against colitis by regulating intestinal HMGCS2-mediated ketogenesis to facilitate mucosal healing.

Article References:
Zhang, Y., Tu, S., Shao, X. et al. Microbiota-derived IPA protects against colitis by regulating intestinal HMGCS2-mediated ketogenesis to facilitate mucosal healing. Nat Commun (2026). https://doi.org/10.1038/s41467-026-69341-z

Image Credits: AI Generated