Lower Protein Intake Mediates Association Between Lower Occlusal Force and Slower Walking Speed: From the Septuagenarians, Octogenarians, Nonagenarians Investigation with Centenarians Study

ObjectivesTo investigate the association between lower extremity motor function and occlusion in older adults and to examine the possibility of dietary intake of protein mediating the association. DesignCross-sectional, population-based study. SettingUrban and rural area in Japan. ParticipantsCommunity-dwelling septuagenarians (N = 655) and octogenarians (N = 629). MeasurementsInformation was collected on occlusal force, protein intake, grip strength, walking speed, sociodemographic characteristics, and medical history. Multivariable logistic regression analysis was used to investigate the association between walking speed, occlusal force, and protein intake, and structural equation modeling analysis and mediation analysis were performed to investigate the validity of the hypothesized model and identify the indirect effect of protein intake in occlusal force and walking speed. ResultsThe proportion of participants whose walking speed was 0.8 m/s or slower (slow walking speed) was 27.7%. Logistic regression analyses showed that slower walking speed was associated with occlusal force (odds ratio = 1.57, P = .001) after adjusting for medical history, body mass index, grip strength, and protein intake. The fit of the hypothesized model that walking speed was associated with occlusal force through protein intake was good, and the indirect effect was significant. ConclusionSlower walking speed was associated with lower occlusal force. Lower protein intake mediated the association between walking speed and occlusal force. Maintaining occlusal force might prevent insufficient nutrition intake and further deterioration of motor function in older people.