Prebiotic Treatment in People With Schizophrenia

This study is testing whether a prebiotic supplement (a dietary fiber that feeds beneficial gut bacteria) can improve symptoms and overall wellbeing in people with schizophrenia or schizoaffective disorder. The idea is that the gut and the brain are connected, and improving gut health may help with mental health. **You may be eligible if...** - You are 18–60 years old with a diagnosis of schizophrenia or schizoaffective disorder - Your condition is currently stable, as determined by your treating psychiatrist - You are currently taking an antipsychotic medication at a stable dose (no changes in the last 14 days) - Your BMI is 40 or under - You can participate in the consent process **You may NOT be eligible if...** - You have a significant gastrointestinal condition like Crohn's disease, IBS, or celiac disease - You have a brain injury, epilepsy, or intellectual disability - You have taken antibiotics recently, or used a probiotic or prebiotic in the last 3 months - You are pregnant or breastfeeding - You have active alcohol or substance misuse (other than mild marijuana use) - You cannot understand English Talk to your doctor to see if this trial is right for you.