Effect of Bifidobacterium on olanzapine-induced body weight and appetite changes in patients with psychosis

Psychopharmacology (Berl). 2021 Sep;238(9):2449-2457. doi: 10.1007/s00213-021-05866-z. Epub 2021 May 17.


Rationale: Gut microbiota plays an important role in host metabolism. Antipsychotic drugs can result in metabolic abnormalities. Probiotics may ameliorate the antipsychotic drug-induced metabolic abnormalities by regulating gut microbiota.

Objective: To determine whether Bifidobacterium intervention can ameliorate olanzapine-induced weight increase.

Methods: Enrolled patients were assigned to either the olanzapine or olanzapine plus Bifidobacterium group. The following were assessed: body weight, body mass index (BMI), appetite, latency to increased appetite, and baseline weight increase of more than 7%. All assessments were conducted at baseline and at 4, 8, and 12 weeks of treatment.

Results: We enrolled 70 patients with schizophrenia or schizophrenic affective disorder, and 67 completed the study. Treatment for 4 weeks led to between-group differences in weight change (2.4 vs. 1.1 kg, p < 0.05) and BMI (0.9 vs. 0.4, p < 0.05). However, this difference disappeared at 8 and 12 weeks of treatment (both p > 0.05). The two groups did not differ in appetite increase at any time point (p > 0.05). The mean time from olanzapine initiation to appetite increase was also not significantly different between the two groups (t = 1.243, p = 0.220).

Conclusions: Probiotics may mitigate olanzapine-induced weight gain in the early stage of treatment and delay olanzapine-induced appetite increase.

Keywords: Appetite; Bifidobacterium; Olanzapine; Schizophrenia; Weight gain.

MeSH terms

  • Antipsychotic Agents* / therapeutic use
  • Appetite / drug effects
  • Benzodiazepines / pharmacology
  • Bifidobacterium
  • Body Mass Index
  • Body Weight / drug effects
  • Humans
  • Olanzapine / therapeutic use
  • Psychotic Disorders* / drug therapy


  • Antipsychotic Agents
  • Benzodiazepines
  • Olanzapine