Thermal Therapy Modulation of the Psoriasis-Associated Skin and Gut Microbiome
Key Findings
- Prospective observational cohort at Terme di Comano, Italy — 57 psoriasis patients underwent a 12-bath balneotherapy course with thermal spring water (not peat); 43 analyzed for skin microbiome, 45 for gut microbiome via paired samples
- 67.4% of patients showed improvement in PASI and/or affected body surface area after the 12-bath course
- Overall bacterial diversity was not significantly different between psoriatic and unaffected skin, and was not significantly altered by balneotherapy — several low-abundance skin genera did shift toward the healthy-skin pattern
- Gut microbiome: no significant change in overall diversity, but a significant convergence toward a more stable bacterial community after treatment, with an increase in species previously linked to favorable metabolic health
- Authors' own caveat: this observational design does not establish causality between the microbiome shifts and clinical improvement, and the specific taxa that changed were largely inconsistent (83.87% discordant) between patients who improved and those who didn't
An observational cohort study proposing microbiome modulation as a candidate mechanism for balneotherapy’s benefit in psoriasis — not peat-specific, and conducted with non-peat thermal spring water at an Italian spa. Included here because it introduces a mechanism not previously represented on this site: see microbiome modulation.
What It Found
Two-thirds of the 57 patients improved clinically after a 12-bath course, but the study wasn’t designed to prove the water caused that improvement — it was designed to look at what happened to the skin and gut microbiome alongside it. Overall bacterial diversity barely moved, but a handful of low-abundance skin bacteria shifted toward patterns seen in healthy (non-psoriatic) skin, and the gut microbiome became more stable, with an increase in bacterial species independently linked to favorable metabolic health in other research.
Why the Caveats Matter
The authors are unusually direct about the limits of their own data: this is a single observational cohort, it doesn’t isolate cause from effect, and the specific bacterial changes were inconsistent between patients who got better and patients who didn’t (over 80% discordant). That’s the honest state of this mechanism — plausible and interesting, not established. It’s graded preliminary on this site’s mechanism page for exactly that reason, and it should not be read as evidence that peat itself affects the microbiome — no study has tested that.