Eleven pounds is a big difference for this simple strategy
STUDY: Huang J et al, Translational Psychiatry 2022;12:185
STUDY TYPE: Randomized, double-blind, placebo-controlled trial
FUNDING: National Natural Science Foundation of China
Background
Antipsychotics change the gut microbiome, which explains part of the mechanism behind their weight gain. Probiotics have some benefits for mental and metabolic health, and this study tested them with schizophrenia.
The Study
This 12-week, double-blind trial from China enrolled 136 adults with schizophrenia or bipolar disorder who had gained weight (at least 10%) on a second generation antipsychotic. They were randomized to one of four arms while the antipsychotic was kept stable:
- Probiotics plus dietary fiber
- Probiotics alone
- Dietary fiber alone
- Placebo
Results
The combination of probiotics with dietary fiber had the best outcomes. They lost 2.36 kg on average, while the placebo group gained 2.63 kg — a nearly 5 kg (11 pound) difference. Probiotics or fiber alone prevented further weight gain but didn’t reverse it.
The combination also protected metabolic health: insulin resistance index (IRI) worsened significantly on placebo but stayed flat in all active treatment arms. Total cholesterol fell in the combination group and rose slightly in placebo. HDL dropped in placebo but held steady elsewhere.
No serious adverse events occurred; constipation was more common on placebo.
Gut microbiota sequencing in a subset of 33 patients showed increased bacterial richness and a favorable shift in the Bacteroidetes/Firmicutes ratio in the combination group — changes linked to less adiposity and better metabolic control in prior studies.
Limitations: single-center design, a Chinese patient population that may limit generalizability, no follow-up beyond 12 weeks, and small stool sample numbers for microbiota analysis.
Practice Implications
- While metformin is recommended first line for antipsychotic weight gain, many patients do not want to take another medicine.
- Probiotics are a good option, and deliver the best results when taken with fiber or a prebiotic.
- The formulation used (Bifico capsules plus a modified fiber drink) isn’t commercially available in US, but the two probiotics on this page were tested by independent labs, use the strains that improve mental health, and contain a prebiotic.
— Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report
