Clay, particularly in the form of medicinal clays like kaolin (china clay) or smectite (e.g., diosmectite), has been used traditionally and in modern medicine for the management of gastrointestinal disorders, including dyspepsia. The primary scientific rationale stems from its adsorptive properties, which allow clay to bind toxins, bacteria, and excess acids in the gastrointestinal tract, potentially alleviating symptoms such as bloating, discomfort, and nausea associated with dyspepsia.

Several clinical studies and reviews—especially in Europe and parts of Asia—have explored the efficacy of diosmectite in functional gastrointestinal disorders. For example, randomized controlled trials have demonstrated that diosmectite may reduce the frequency and severity of symptoms in patients with acute diarrhea and functional dyspepsia, although the effect size is typically modest and not all studies agree. Mechanistically, smectite clays appear to reinforce the mucosal barrier and reduce gut permeability, which could have benefits for some dyspeptic patients.

However, while there is some scientific support, the overall quality of the evidence is limited by small sample sizes, short study durations, and inconsistent endpoints. Major gastroenterological guidelines do not recommend clay as a first-line therapy for dyspepsia, reflecting the need for more rigorous research. As such, the evidence is best rated as moderate to low (2 on a 0-5 scale).