An 8-week standardized wild thyme (Thymus serpyllum) extract reduced self-reported gastrointestinal symptom burden and improved selected quality-of-life outcomes versus placebo in adults with persistent gastrointestinal discomfort, was well tolerated, and was linked to taxon-level (but not global diversity) changes in the fecal microbiome.
Wild thyme extract (WThE) produced a greater reduction in overall gastrointestinal symptom burden than placebo, as measured by the GSRS total score.
The largest exploratory domain-level differences in GI symptoms between WThE and placebo were in indigestion, constipation, and diarrhea-related symptoms.
WThE improved selected health-related quality-of-life outcomes.
No significant between-group differences in fecal microbiome α- or β-diversity were detected.
Taxon-level analyses identified specific changes in fecal microbial composition with WThE, and predicted functional profiling suggested pathway-level differences.
WThE was well tolerated, with no product-related adverse events reported during the 8-week intervention.
This study tested whether a standardized extract of wild thyme (Thymus serpyllum) could ease ongoing digestive discomfort in adults who had no diagnosed digestive disease. About 178 people were randomly assigned to take either the extract or a placebo for 8 weeks, without knowing which they received. The group taking the extract reported a larger drop in overall digestive symptoms than the placebo group, with the biggest differences seen in indigestion, constipation, and diarrhea-related symptoms. Participants on the extract also reported improvements in some quality-of-life measures. The researchers also looked at gut bacteria in stool samples. The overall diversity of the gut microbial community did not differ between groups, but some specific bacterial groups changed, and computer-based predictions suggested differences in microbial functions. These microbiome findings were exploratory and do not prove that bacterial changes caused the symptom improvements. No product-related side effects were reported. This research suggests wild thyme extract may be a well-tolerated option for reducing everyday digestive discomfort. Important caveats are that only 131 of the 178 participants had week-8 data, that the domain-level and microbiome results were exploratory, and that larger and longer studies would be needed to confirm the findings.
López-Zambrano R, García-García J, López-Escánez L, Vezza T, Gbati L, Palacios-López R, et al.. (2026). Thymus serpyllum Extract Improves Gastrointestinal Symptoms and Modulates Fecal Gut Microbiome Composition in a Multicenter, Randomized, Placebo-Controlled Clinical Trial.. Medical sciences (Basel, Switzerland). https://doi.org/10.3390/medsci14060611