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Carbonic acid tablets containing citric acid and sodium bicarbonate were designed to dissolve in aqueous solution, and release carbon dioxide (CO2). The effect of the carbonic acid tablets on salivary secretion was examined in humans. Healthy male volunteers participated in the whole salivary flow secretion (n = 6) and submandibular-sublingual (SMSL) gland and parotid gland salivary flow secretion (n = 12) studies. Placement of a carbonic acid tablet on the apex of the tongue increased the whole saliva volume. The carbonic acid tablets promoted SMSL salivary secretion, but had less effect on parotid salivary secretion. A citric acid tablet, an acidic tastant, promoted both SMSL and parotid salivary secretion. A tablet containing only sodium bicarbonate, a component of the carbonic acid tablet, had no effect on SMSL salivary secretion. In conclusion, a carbonic acid stimulus specifically enhances salivary secretion from SMSL glands via the formation of CO2.