Effect of Inulin-Type Fructans on Body Composition, Carbohydrate Metabolism and Energy Expenditure in Patients with Psoriasis: Results of INGUTSKIN Randomized Controlled Trial

Introduction: Patients with psoriasis, a non-contagious, chronic, systemic inflammatory skin disease, often suffer from carbohydrate metabolism disorders, which can exacerbate systemic inflammation. Methods: This randomized, double-blind, placebo-controlled trial (RCT) evaluated the effects of chicory-derived inulin-type fructans (ITFs) on body composition, energy expenditure, and carbohydrate metabolism in patients with mild psoriasis (PS), using a healthy control (n = 32) group as a baseline reference. PS participants (n = 56) were randomized to receive 15 g/day of ITFs (n = 29) or a placebo (n = 27) for 8 weeks. Body composition using bioelectrical impedance analysis (BIA), carbohydrate metabolism (fasting glucose, insulin, glycated hemoglobin, Oral Glucose Tolerance Test (OGTT)) and resting energy expenditure (resting metabolic rate (RMR), oxygen consumption (VO₂), carbon dioxide production (VCO₂)) via indirect calorimetry were determined. Results: At baseline, patients with PS had significantly (p < 0.01) higher body mass index and visceral fat levels, and abnormal levels of selected parameters of carbohydrate metabolism, compared with healthy controls. Following the intervention, the ITFs group maintained stable fasting glucose levels, while the placebo group showed an undesirable increase (Δ_glucose = +5.7 mg/dL; p < 0.01). The energy expenditure analysis revealed a significant treatment effect on RMR and VO₂ parameters (p < 0.01), with a decrease in the placebo group (p < 0.01) while remaining stable in the prebiotic group. There was no significant effect of the intervention on body composition and anthropometric parameters. Conclusions: Patients with PS exhibit a higher metabolic risk than healthy controls. Although no significant changes were observed within the intervention groups, the deterioration of metabolic indices in the placebo group may indicate an unfavorable effect of the maltodextrin. Consequently, the stabilization of parameters in the prebiotic group should be interpreted with great caution. This RCT was registered at ClinicalTrials.gov (NCT05971992).