Dietary fiber and probiotics for the treatment of atypical antipsychotic-induced metabolic side effects: study protocol for a randomized, double-blind, placebo-controlled trial

Background Atypical antipsychotic medications, which are effective for the treatment of schizophrenia and bipolar disorder, are associated with features of metabolic syndrome, such as weight gain, hyperglycemia, dyslipidemia, and insulin resistance. Although there are a few studies on the effects of dietary fiber or probiotics on weight loss in obese people, no published trials have reported the efficacy of dietary fiber and probiotics on reducing atypical antipsychotic-induced weight gain. Methods For this 12-week randomized, double-blind, placebo-controlled study, 100 patients with a weight gain of more than 10% after taking atypical antipsychotic medications were recruited. Participants were randomized to four groups as follows: probiotics (840 mg twice daily (bid)) plus dietary fiber (30 g bid), probiotics (840 mg bid) plus placebo, placebo plus dietary fiber (30 g bid), or placebo group. The primary outcome was the change in body weight. Secondary outcomes included changes in metabolic syndrome parameters, appetite score, biomarkers associated with a change in weight, and gut microbiota composition and function. Discussion To date, this is the first randomized, placebo-controlled, double-blinded trial investigating the efficacy of dietary fiber and probiotics alone and in combination to reduce metabolic side effects induced by atypical antipsychotic medications. If effective, it is possible to conclude that dietary fiber and probiotics can reduce atypical antipsychotic-induced metabolic side effects. Trial registration number ClinicalTrials.gov NCT03379597. Registered on 19 November 2017.