Mechanisms of action and clinical effectiveness of herbal treatments for disorders of gut-brain interaction.

Disorders of gut-brain interaction (DGBI), such as functional dyspepsia (FD) and irritable bowel syndrome (IBS), affect about one-third of the global population. Many patients turn to traditional and herbal medicines for relief, given the lack of effective therapies. This review assesses the clinical and preclinical evidence for herbal treatments used for patients with DGBI. Placebo-controlled trials show that specific herbal preparations, including peppermint oil, ginger, and commercial formulations like STW-5, ZZKZ and Rikkunshito significantly improve gastrointestinal symptoms. Their effectiveness likely arises from various mechanisms, such as alterations in gastrointestinal motility, desensitization of visceral sensory function, and suppression of low-grade mucosal or systemic inflammation. Recent studies of the effects of herbal extracts on the gastrointestinal microbiome also implicate microbial involvement in their effectiveness. Most herbal preparations contain multiple bioactive compounds to address various disease mechanisms, and there remains a significant gap in dose-response studies for optimizing therapeutic outcomes.