One Size Fits None: A Comparative Analysis of the Low-FODMAP Diet and the Tayyibat Exclusionary System Using an Evidence-Based Comparator

Background: The dietary landscape features two contrasting approaches to gastrointestinal symptom management: the evidence-based Low-FODMAP diet, developed through systematic research at Monash University, and the Tayyibat system, a non-standardised exclusionary protocol that imposes permanent, universal prohibitions on entire food categories. Despite overlapping short-term symptom relief, these systems differ fundamentally in their scientific basis, duration, reintroduction protocols, and safety profiles. A critical gap exists in the literature: no comprehensive comparative biochemical analysis has systematically examined these dietary approaches side-by-side. Objective: This study provides a comparative analysis of the Low-FODMAP diet and the Tayyibat exclusionary system using an evidence-based comparator framework. The analysis examines biochemical mechanisms, clinical evidence, nutritional adequacy, microbiome effects, and safety across both systems. By integrating nutrigenetic and nutrigenomic evidence—including gene-diet interactions involving TCF7L2 and APOE polymorphisms—this analysis further aims to establish a genomically-informed foundation for future precision nutrition research and personalised dietary intervention. Methods: The study employs a hypothesis-driven narrative/critical comparative review methodology, integrating evidence from randomised controlled trials, meta-analyses, nutrigenetic studies, and mechanistic biochemical analyses. Primary source materials for the Tayyibat system were analysed alongside peer-reviewed literature on FODMAP biochemistry, gastrointestinal physiology, microbiome ecology, and nutrigenomics. Due to the absence of clinical data for the Tayyibat system, this study applies established biochemical and nutrigenetic principles to evaluate mechanistic plausibility and potential long-term metabolic risks. Results: The Low-FODMAP diet is supported by extensive evidence from RCTs and meta-analyses, demonstrating 70-75% symptom improvement in IBS patients. Its three-phase structure respects biological individuality, preserves microbiome diversity, and avoids permanent nutritional deficiencies. In contrast, the Tayyibat system lacks any peer-reviewed evidence, imposes permanent prohibitions that create predictable micronutrient deficiencies (choline, calcium, iron, vitamin D), promotes progressive microbiome depletion, and encourages medication abandonment with documented patient harm. Conclusions: Evidence-based, individualised dietary approaches are scientifically superior to universal, permanent prohibitions. The Low-FODMAP diet exemplifies principles of personalised nutrition, while the Tayyibat system represents the dangers of non-evidence-based dietary guidance. Nutrigenetic evidence demonstrates that universal dietary recommendations are biologically implausible. These findings highlight gene-diet interaction as a critical and underexplored frontier, underscoring the need for dedicated genomic research programmes to advance individualised, precision-based dietary intervention. The imperative for evidence-based practice in nutrition has never been clearer: one size fits none.