Disorders of Gut-Brain Interaction and Psychological Distress Affect Dietary Behavior: Italian Data From the Worldwide Rome Foundation Global Epidemiology Study

Background: Disorders of gut-brain interaction (DGBI) are highly prevalent and frequently associated with psychological distress and meal-related symptoms. While the habitual Italian diet is Mediterranean and nutritionally protective, its high content of fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) may exacerbate gastrointestinal (GI) discomfort in susceptible individuals. The extent to which DGBI and psychological distress are associated with real-world dietary behavior remains unclear. Methods: Data from the Italian arm of the Rome Foundation Global Epidemiology Study (n = 1930) were analyzed. Participants were classified as controls, diagnostic groups (DGBI and sub-diagnostic DGBI) according to Rome IV criteria, and stratified by psychological distress (PHQ-4 < 6 = low; ≥ 6 = high) and GI symptom frequency. Habitual diet was assessed as weekly frequency of consumption of general food categories as well as predefined high-FODMAP (HF) and low-FODMAP (LF) groups. Multivariable negative binomial regression models were used to examine associations among diagnostic groups, psychological distress, GI symptom frequency, and weekly intake of general and FODMAP-classified foods. Results: DGBI affected 46.1% of participants, 20.2% were sub-diagnostic, and 33.7% were controls. High psychological distress was more frequent in DGBI (28.1%) and sub-diagnostic groups (19.0%) than in controls (6.2%) and increased with symptom frequency (adjusted rate ratio [aRR]: 3.90, 95% CI: 2.83–5.38 for DGBI vs. controls). Compared to controls, DGBI participants with low distress reported modest reductions in LF fruits (aRR: 0.94, 95% CI: 0.88–1.00) and vegetables (aRR: 0.91, 95% CI: 0.86–0.97), whereas those with high distress reported broader, nonselective restriction of both HF and LF fruits (aRR: 0.83–0.85) and vegetables (aRR: 0.92, 95% CI: 0.85–1.00). Compared to controls, sub-diagnostic participants without distress reported mild reductions in dairy and fruit intake; those with distress were too few for reliable analysis. Carbohydrate staples (bread, pasta, pizza) did not differ across all groups. Conclusions: Psychological distress exerts a dominant, emotion-driven influence on dietary behavior, promoting nonselective restriction of plant foods independent of FODMAP content. These findings highlight the need for integrated psycho-nutritional interventions that combine psychological support with culturally adapted Mediterranean dietary guidance to preserve nutritional adequacy and improve gut-brain health.