Natural polysaccharides and depression: systematic review of preclinical evidence via the microbiota-gut-brain axis
A systematic review of 20 preclinical studies associates natural polysaccharides with improved depression-like behaviors in animal models, but reports substantial heterogeneity and high risk of bias.
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What the study showed
Polysaccharide treatment was generally associated with reduced depression-like behaviors, normalized neurotransmitter levels, and decreased inflammation and oxidative stress in animal models. These effects were accompanied by changes in intestinal barrier function, gut microbiota composition, and short-chain fatty acid metabolism. The authors explicitly acknowledge substantial heterogeneity and high risk of bias across included studies.
How it was done
Systematic review following PRISMA guidelines, searching PubMed, Web of Science, and Embase up to October 4, 2025. Twenty preclinical studies met inclusion criteria.
Risk of bias
All 20 included studies are preclinical; no human data are available. High risk of bias and substantial heterogeneity preclude causal interpretation, as stated by the authors themselves.
What this study does NOT prove
This review does not demonstrate antidepressant efficacy of polysaccharides in humans, nor does it establish causality between gut microbiota and depression.
In clinical practice
No clinical application or therapeutic recommendation is supported by this review. Translational and clinical studies are explicitly identified as necessary next steps.
Limitations
All 20 included studies are preclinical; no human data are available. High risk of bias and substantial heterogeneity preclude causal interpretation, as stated by the authors themselves.
Technical appendix
Version history
- 1.0 · 2026-07-15 — Auto-generated under Evidence Standard v1.0
Paid access: structured summary from public metadata; consult the original study at the source.