The aryl hydrocarbon receptor (AhR) is a nuclear protein which, upon association with certain endogenous and exogenous ligands, translocates into the nucleus, binds DNA and regulates gene expression. Tryptophan (Trp) metabolites are one of the most important endogenous AhR ligands. The intestinal microbiota is a critical player in human intestinal homeostasis. Many of its effects are mediated by an assembly of metabolites, including Trp metabolites. In the intestine, Trp is metabolized by three main routes, leading to kynurenine, serotonin, and indole derivative synthesis under the direct or indirect involvement of the microbiota. Disturbance in Trp metabolism and/or AhR activation is strongly associated with multiple gastrointestinal, neurological and metabolic disorders, suggesting Trp metabolites/AhR signaling modulation as an interesting therapeutic perspective. In this review, we describe the most recent advances concerning Trp metabolism and AhR signaling in human health and disease, with a focus on nutrition as a potential therapy to modulate Trp metabolites acting on AhR. A better understanding of the complex balance between these pathways in human health and disease will yield therapeutic opportunities.

The increase in incidences of pediatric Crohn’s Disease (CD) worldwide has been strongly linked with dietary shifts towards a Westernized diet, ultimately leading to altered gut microbiota and disturbance in intestinal immunity and the metabolome. Multiple clinical studies in children with CD have demonstrated the high efficacy of nutritional therapy with exclusive enteral nutrition (EEN) to induce remission with an excellent safety profile. However, EEN is poorly tolerated, limiting its compliance and clinical application. This has spiked an interest in the development of alternative and better-tolerated nutritional therapy strategies. Several nutritional therapies have now been designed not only to treat the nutritional deficiencies seen in children with active CD but also to correct dysbiosis and reduce intestinal inflammation. In this review, we report the most recent insights regarding nutritional strategies in children with active CD: EEN, partial enteral nutrition (PEN), Crohn’s disease exclusion diet (CDED), and CD treatment-with-eating diet (CD-TREAT). We describe their setup, efficacy, safety, and (dis)advantages as well as some of their potential mechanisms of action and perspectives. A better understanding of different nutritional therapeutic options and their mechanisms will yield better and safer management strategies for children with CD and may address the barriers and limitations of current strategies in children.

Excessive crying, often described as infantile colic, is the cause of 10% to 20% of all early pediatrician visits of infants aged 2 weeks to 3 months. Although usually benign and self-limiting, excessive crying is associated with parental exhaustion and stress. However, an underlying organic cause is found in less than 5% of these infants. In the majority of cases, treatment consists not of “curing the colic,” although usually it is possible to reduce crying, but of helping the parents to get through this challenging period in their baby’s development. The aims of this review are to discuss definition, etiology, and evaluate different treatment regimes in infants who cry excessively.

Probiotics are increasingly used in the treatment of functional gastrointestinal disorders. Studies in constipated adults with a Bifidus yoghurt (containing Bifidobacterium breve, Bifidobacterium bifidum and Lactobacillus acidophilus) showed a significant increase in defecation frequency. The aim of this pilot study was to determine if Bifidobacterium breve is effective in the treatment of childhood constipation.

Irritable bowel syndrome (IBS) and functional abdominal pain (syndrome) (FAP(S)) are common pediatric disorders, characterized by chronic or recurrent abdominal pain. Treatment is challenging, especially in children with persisting symptoms. Gut-directed hypnotherapy (HT) performed by a therapist has been shown to be effective in these children, but is still unavailable to many children due to costs, a lack of qualified child-hypnotherapists and because it requires a significant investment of time by child and parent(s). Home-based hypnotherapy by means of exercises on CD has been shown effective as well, and has potential benefits, such as lower costs and less time investment. The aim of this randomized controlled trial (RCT) is to compare cost-effectiveness of individual HT performed by a qualified therapist with HT by means of CD recorded self-exercises at home in children with IBS or FAP(S).

Neurogenic/neuropathic bowel dysfunction (NBD) is common in children who are affected by congenital and acquired neurological disease, and negatively impacts quality of life. In the past, NBD received less attention than neurogenic bladder, generally being considered only in spina bifida (the most common cause of pediatric NBD). Many methods of conservative and medical management of NBD are reported, including relatively recently Transanal Irrigation (TAI). Based on the literature and personal experience, an expert group (pediatric urologists/surgeons/gastroenterologists with specific experience in NBD) focused on NBD in children and adolescents. A statement document was created using a modified Delphi method. The range of causes of pediatric NBD are discussed in this paper. The various therapeutic approaches are presented to improve clinical management. The population of children and adolescents with NBD is increasing, due both to the higher survival rate and better diagnosis. While NBD is relatively predictable in producing either constipation or fecal incontinence, or both, its various effects on each patient will depend on a wide range of underlying causes and accompanying comorbidities. For this reason, management of NBD should be tailored individually with a combined multidisciplinary therapy appropriate for the status of the affected child and caregivers.