Dietary strategies for chronic constipation: smartly targeting hormonal and reflex pathways for optimal recovery

Chronic constipation (CC) is a common disorder of gut-brain interaction that markedly impairs quality of life and remains challenging to manage. Despite the availability of laxatives and prosecretory agents, up to half of patients experience suboptimal relief, underscoring the need for complementary, physiology-based nutritional strategies. Nutrients influence intestinal motility through multiple pathways, including enteroendocrine signalling, bile-acid metabolism, microbiota-derived metabolites, and intestinal taste-receptor activation. Integrating these mechanisms into clinical nutrition requires structured approaches that align fiber type, bile flow, microbial modulation, and sensory stimulation with motility phenotype and fermentation tolerance. Among dietary interventions, the most consistent clinical evidence supports the use of soluble fiber (e.g., psyllium), kiwifruit or prunes, and magnesium- or sulfate-rich mineral waters to improve stool frequency and consistency. Other components, such as fermented foods, probiotics, and generic hydration, show variable efficacy and remain supported primarily by physiological or translational data. The SMART (Sensory, Motor, bile Acid and Reflex Tailored) Constipation Diet (SCD) is proposed as a hypothesis-generating dietary framework that integrates fiber optimization, bile stimulation, microbial support, and chrono-nutritional timing into a coherent dietary model. Given the heterogeneity of CC (e.g., functional constipation, IBS-C, defecatory disorders) and the scarcity of phenotype-stratified trials, the SCD should be regarded as a translational concept rather than a validated clinical protocol. Future randomized, controlled studies with hard motility and symptom outcomes are needed to determine whether coordinated, multi-pathway dietary modulation can outperform single-component interventions and advance precision nutrition in CC.