Effects of synbiotic supplementation on the components of metabolic syndrome in patients with schizophrenia: a randomized, double-blind, placebo-controlled trial

Background: Antipsychotic drugs may have adverse effects on the components of metabolic syndrome. Previous studies have shown that changes in the intestinal microbiome are associated with metabolic disturbances in patients with schizophrenia. The objective of this study was to determine the effects of synbiotics on the components of metabolic syndrome as primary outcomes in patients with schizophrenia. Secondary outcomes were HbA1c, insulin resistance, LDL-c, and anthropometric measurements.

Methods: In this double-blind, placebo-controlled trial, seventy patients with schizophrenia receiving antipsychotic drugs who had at least two criteria of metabolic syndrome were randomly divided into two groups to receive either two capsules of a synbiotic supplement or a placebo daily for 8 weeks. Anthropometric indices and biochemical parameters were measured at baseline and after the intervention.

Results: Fifty-five patients completed the study. The synbiotic supplement significantly decreased waist circumference and HbA1C compared to placebo (-2.66 ± 4.20 vs. 3.03 ± 4.50 and - 0.26 ± 0.54 vs. 0.20 ± 0.75, respectively). Although BMI did not change significantly in the synbiotic + antipsychotic group, it increased in the placebo + antipsychotic group (-0.37 ± 1.00 vs. 0.61 ± 1.09 P < 0.5). LDL-c and triglyceride (TG) levels decreased significantly in the synbiotic + antipsychotic group, but the change was not significantly different from that of the placebo + antipsychotic group. FBS, HDL-c, systolic and diastolic blood pressure, insulin resistance, and total cholesterol were not significantly different between the two groups after intervention.

Conclusion: Synbiotic supplement may decrease waist circumference, HbA1c, LDL and TG and prevent BMI increase in patients receiving antipsychotic drugs.

Trial registration: Iranian Registry of Clinical Trials (IRCT Number: IRCT20090901002394N45), Date: 26-12-2019.