Restoring an adequate dietary fiber intake by inulin supplementation: a pilot study showing an impact on gut microbiota and sociability in alcohol use disorder patients

Alcohol use disorder (AUD) is a chronic relapsing disease associated with malnutrition, metabolic disturbances, and gut microbiota alterations that are correlated with the severity of psychological symptoms. This study aims at supplementing AUD patients with prebiotic fiber during alcohol withdrawal, in order to modulate the gut microbiota composition and to evaluate its effect on gastrointestinal tolerance, metabolism, and patient's behavior. A randomized, double-blind, placebo-controlled study included 50 AUD patients assigned to inulin versus maltodextrin daily supplementation for 17 days. Biological measurements (fecal microbial 165 rDNA sequencing, serum biology), dietary intake, validated psychological questionnaires, and gastrointestinal tolerance assessment were performed before and after the intervention. Inulin significantly decreased the richness and evenness and induced changes of 8 genera (q < 0.1) including Bifidobacterium and Bacteroides. Prebiotic had minor effects on gastrointestinal symptoms and nutritional intakes compared to placebo. All patients showed an improvement in depression, anxiety, and craving scores during alcohol withdrawal regardless of the intervention group. Interestingly, only patients treated with inulin significantly improved the sociability score and had an increased serum level of brain-derived neurotrophic factor. This pilot study shows that inulin is well tolerated and modulates the gut microbiota and the social behavior in AUD patients, without further improving other psychological and biological parameters as compared to placebo.