The excessive intake of dietary salt is a global issue in health. Attempts have been made to address this issue, including the development of salt substitutes. Yet, none of these substances are currently in wide use, because of their weak saltiness. The purpose of this study was to assess the effects of sodium aspartate (Asp-Na) on salty taste perception using the bullfrog glossopharyngeal nerve response and human sensory tests. When added to the mixture of NaCl and KCl, Asp-Na significantly enhanced the glossopharyngeal nerve response to the mixture by 1.6-fold compared to control. Asp-Na did not enhance the response to NaCl, nor did Asp-Na enhance the response to sour, bitter, or umami stimuli. The optimal concentration for Asp-Na to enhance the salt mixture was 1.7mM. The largest enhancement was induced when NaCl and KCl were mixed at equimolar concentrations. Asp-Na significantly suppressed the glossopharyngeal nerve response to quinine hydrochloride, which suggests that bitterness of KCl is suppressed by Asp-Na. The salty taste enhancing effect of Asp-Na was also confirmed with human sensory tests. The present results suggested that the mixture of NaCl and KCl containing Asp-Na can be used as a salt substitute. In addition to demonstrating that Asp-Na enhanced salt taste responses in an experimental animal and human, our findings provide clues to identify the elusive salty taste receptors.
Keywords: nerve response; potassium chloride; reducing salt intake; salt substitute; salt taste receptor; salty taste enhancing substance.
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