Effects of Aging on the Relationship between Ionic Components in Saliva and Salt Taste Preference

Because excessive intake of salt causes high blood pressure and renal failure, regulation of salt intake is important for maintenance of health. The amount of salt intake may be influenced by perception of salt taste, i.e. the recognition threshold for salty taste and salt concentration that makes food good taste（preference concentration）. Although salt intake increases with age, the effect of age on salty taste perception is unclear. We have previously reported that preference for salty taste was associated with ion concentrations in saliva. Because saliva components was also reported to change with age, ion concentrations in saliva may be a factor that affects the sensitivity and preference for salt of elderly people. To clarify the determinants to increase salt intake of elderly people, we measured the perception of salty taste and concentrations of sodium and potassium ions in 75 adult volunteers. We also conducted a questionnaire on dietary habits to examine the preference degree and intake frequency for salty foods. The subjects were divided into the younger（＜40 y）and elder（≧40 y）groups. Significant differences were not observed between the two groups except for intake frequency of salty foods. In the elder group, the positive correlations were observed between sodium ion concentration in the resting saliva and recognition threshold, preference concentration and preference degree, which were not shown in the young group. These results suggest that long-standing dietary habits affected saliva components, which in turn affected taste perception.