Beyond Hydration: Natural Mineral Water and Metabolic Health

Background: Natural mineral water (NMW) is a heterogeneous dietary exposure whose composition varies substantially among sources. Objective: This critical review examines human intervention evidence on NMW in relation to metabolic health across healthy adults and populations with hypercholesterolaemia, type 2 diabetes mellitus (T2DM), and metabolic dysfunction-associated steatotic liver disease (MASLD) while separating direct clinical findings from mechanistic evidence. Methods: Seven principal human intervention studies were identified in the clinical synthesis. Results: Controlled studies did not show a reproducible glucose-lowering effect attributable to mineralwater composition. Selected studies nevertheless reported changes in postprandial insulin dynamics, glycoalbumin, oxidative status, gastrointestinal or microbiota-related variables, and intestinal, inflammatory, and hepatic outcomes. Calcium and magnesium in mineral water are bioavailable, but mineral absorption should not be interpreted as evidence of disease-specific efficacy. The literature is constrained by small samples, chemically dissimilar waters, heterogeneous populations, variable intervention durations, and inconsistent comparator designs. Conclusions: Accordingly, current evidence supports NMW primarily as a source-specific nutritional exposure rather than an established metabolic intervention. Future trials should use analytically characterized intervention and control waters, predefined outcomes, adequate durations, and clearly defined metabolic phenotypes to determine whether particular hydrochemical profiles produce reproducible metabolic effects.