Gut microbiota transplant might help antidepressants work faster

30.10.2026

The microbial changes associated with FMT are accompanied by increases in bile acids and reductions in inflammatory signals, which may help explain the antidepressant effect

What is already known

Depression is common and often difficult to treat. Standard antidepressants help many people with depression, but a large fraction of them do not reach remission. Gut microbes are known to influence brain function, and thus may also affect how people respond to antidepressants. But it’s unclear whether reshaping the gut microbiota could improve the effects of antidepressants.

What this research adds

Researchers tested whether fecal microbiota transplantation (FMT) could improve treatment for depression when added to escitalopram, a standard antidepressant. They gave 60 people with depression either FMT or placebo for 2 weeks and then followed them for 8 weeks. FMT did not improve remission at week 8. But people receiving FMT improved faster: by week 2, more had a 50% drop in depression scores. FMT was well tolerated, and analyses suggested that donor microbes partly took hold in the guts of recipients, changed bile-acid levels, and reduced inflammatory signals.

Conclusions

The findings suggest that reshaping the gut microbiota may help antidepressants work faster and better, likely through effects on bile acids and inflammation.

Depression is a common condition that affects mood, sleep, appetite and physical health, and many people do not fully recover with standard antidepressants alone. Now, researchers have found that combining microbiota transplants with antidepressant treatment may help people with depression improve faster, although it did not significantly increase remission.

The findings, published in Cell Host & Microbe, suggest that reshaping the gut microbiota may help antidepressants work faster and better, likely through effects on bile acids and inflammation.

Gut microbes are known to influence brain function, and thus may also affect how people respond to antidepressants. But it’s unclear whether reshaping the gut microbiota could improve the effects of antidepressants.

Researchers led by Jing Li at Capital Medical University in Beijing, China, tested whether fecal microbiota transplantation (FMT) could improve treatment for depression when added to escitalopram, a standard antidepressant.

Faster improvement

Study participants were, on average, about 30 years old and 40% were experiencing a first episode of major depression. The researchers gave 60 participants either FMT or placebo for 2 weeks and then followed them for 8 weeks.

FMT did not improve remission—defined as a low score on a standard depression rating scale—at week 8. But people receiving FMT improved faster: by week 2, more had a 50% drop in depression scores, compared with 6.7% in the placebo group.

By week 8, depression scores had fallen more in the FMT group than in the placebo group, suggesting that FMT may have boosted the antidepressant effect even though it did not improve remission, the authors say.

Microbial shifts

FMT was well tolerated, and analyses suggested that donor microbes partly took hold in the guts of recipients. By week 2, FMT increased microbial diversity and shifted the recipients’ gut communities toward a more donor-like pattern, including decreases in some bacteria linked to inflammation.

Further analyses suggested that these microbial changes were accompanied by increases in bile acids and reductions in inflammatory signals, which may help explain the antidepressant effect, the researchers say.

Although the trial did not meet its main remission endpoint, they add, “FMT may provide a safe avenue to enhance escitalopram efficacy through microbiota-directed regulation of bile-acid metabolism and inflammation.”