[Determinants of salt taste threshold among urban residents: the KOBE study].

Objectives　Though having a high salt taste threshold has been associated with hypertension, its exact determinants remains unclear. This study aimed to identify the determinants of salt taste threshold in a community-based population and to determine the relationship between salt taste thresholds and the simultaneous presence of multiple determinants.Methods　Of the 1,117 participants of the baseline survey of the Kobe study, a cohort study of healthy urban residents, aged 40-74 years, with no history of cancer or cardiovascular diseases, nor undergoing treatment for hypertension, diabetes, or dyslipidemia, was conducted. Among them, 1,116 underwent the salt taste threshold test, and urine samples were collected to determine their estimated salt intake. The salt taste threshold test was carried out using SALSAVE, with a salt taste threshold of 0.6% defined as normal, and that of 0.8% or more defined as high. A binomial logistic regression model was used, with high salt taste threshold as the objective variable, and life and family status, education, smoking and alcohol drinking status, intake status of salt dried fish, stress indicators, and daily salt intake (estimated from the urine sample) as the explanatory variables. A binomial logistic regression analysis was conducted, through multivariate analysis using the forced entry method, with factors influencing salt taste threshold as explanatory variables, and salt taste threshold (normal/high) as the objective variable. This analysis was performed excluding the urinary sodium-to-potassium ratio to account for multicollinearity with the estimated daily salt intake.Results　The mean age was 60.9±9.0 years for men, and 58.0±8.7 years for women. The salt taste threshold was normal in 80.9% (n=903) of the participants (73.6% [n=251] men and 84.1% [n=652] women), and high in 19.1% (n=213) of the participants (26.3% [n=90] men and 15.9% [n=123] women). Multivariate analysis revealed that smoking habits were significantly associated with a higher salt taste threshold, with an odds ratio (95% confidence interval) of 2.51 (1.33-4.74) for all participants. The odds ratio for a high salt taste threshold was 1.45 (1.03-2.03) for the top 25% estimated daily salt intake group, showing a significant association with a high salt taste threshold. In the analysis by sex, smoking habits were associated with higher salt taste thresholds, while an association with estimated daily salt intake was observed only in men.Conclusion　Smoking status and estimated daily salt intake were associated with higher salt taste thresholds in healthy urban residents.