Functional dyspepsia (FD) is one of the most common disorders of gut-brain interaction (DGBI), with an estimated prevalence of 7-8% in the general population. It is defined by Rome IV criteria as bothersome postprandial fullness, early satiety, epigastric pain, or burning, persisting for at least 3 months with onset at least 6 months before diagnosis, and without evidence of structural disease. FD is associated with impaired quality of life, psychological distress, and significant health care utilization. Current treatment options, including proton pump inhibitors and prokinetics, have limited efficacy and potential adverse effects when used long term.
Emerging evidence suggests a role of the gastrointestinal microbiota in FD pathophysiology. Alterations in duodenal microbiota, as well as small intestinal bacterial overgrowth (SIBO) promoted by chronic PPI use, have been reported. Probiotics may reduce dyspeptic symptoms, improve gut barrier function, modulate gastric motility, and exert anti-inflammatory effects.
A randomized controlled trial showed that Bacillus coagulans MY01 and Bacillus subtilis MY02 improved FD symptoms compared to placebo, with good safety and tolerability. In parallel, ginger (Zingiber officinale) has a well-documented gastroprotective effect, supported by both preclinical and clinical data, and has been shown to enhance gastric emptying and reduce upper gastrointestinal discomfort.
The present study (SUBTILE, STO-253) is a prospective, multicenter, interventional trial conducted in France, categorized as RIPH2 (research involving human participants at minimal risks and constraints) under French regulations. The study will evaluate the effect of a dietary supplement combining Bacillus coagulans MY01, Bacillus subtilis MY02, and ginger extract (50 mg, 20% gingerols), marketed in France since January 2025 as Symbiosys® Stomalex.
A total of 198 adult patients with FD (Rome IV criteria, normal endoscopy) will be recruited in primary care and gastroenterology practices. After providing informed consent, eligible participants will receive one capsule per day for 8 weeks. The study involves two in-person visits (baseline and Week 8) and one telephone follow-up at Day 28.
The primary endpoint is the change in total PAGI-SYM score from baseline to Week 8.
Secondary endpoints include changes in PAGI-QoL scores, treatment adherence, use of concomitant therapies, evolution of lower gastrointestinal symptoms, global impressions of change from both patients (PGI-C) and physicians (CGI-I), and satisfaction ratings. An exploratory endpoint evaluates psychological impact using the Hospital Anxiety and Depression Scale (HADS). Safety endpoints include frequency and severity of adverse events.
This study will provide additional clinical evidence on the potential role of spore-forming probiotics combined with ginger extract as a complementary non-pharmacological approach to improve digestive symptoms and quality of life in patients with functional dyspepsia.
