The association between masticatory ability and lower Timed Up & Go Test performance among community-dwelling Japanese aging men and women: The Toon Health Study

Few studies examined the association between deterioration of masticatory ability assessed by objective marker and physical function. Therefore, we examined the association between salivary flow rate which is one of the objective and surrogate marker of masticatory ability and lower Timed Up & Go (TUG) performance which is one of major measurement of physical function among aging Japanese. This cross-sectional study enrolled 464 Japanese aged 60–84 years old. Participants chewed tasteless and odorless gum for 5 min, calculated stimulated salivary flow rate (g/min) during all chews. The 3 m TUG was conducted, and 75th percentile value (6.8 s for men and 7.0 s for women) or higher was defined as lower TUG performance. Logistic regression analysis was used to examine the association between stimulated salivary flow rate and lower TUG performance. We found that the stimulated salivary flow rate tended to be negatively associated with the TUG time. We also observed significant negative association between stimulated salivary flow rate and lower TUG performance; the multivariable-adjusted OR (95% confidence interval, CIs) of lower TUG performance for the highest quartile of stimulated salivary flow rate compared with the lowest quartile was 0.34 (0.16–0.69, P for trend = 0.02). Further adjusting for BMI, the association was attenuated but remaind significant; the OR (95% CIs) in highest quartile was 0.37 (0.18–0.76, P for trend = 0.04). Higher stimulated salivary flow, which means well masticatory ability, was inversely associated with lower TUG performance in the aging Japanese population.