The relationship between oral function and body mass index among independently living older Japanese people

This study aimed to clarify the relationship between oral function and Body Mass Index (BMI) using data from independently living, relatively healthy older people. The hypothesis was that oral function is more important than dental status for healthy body weight.

The subjects were community-dwelling, independently living elderly people over 60 years of age (N = 807, 408 men and 399 women). An oral health examination, an oral and general health interview, and measurement of oral function, such as masticatory performance and occlusal force, were carried out. BMI (kg/m2) was used to measure body fat. A multiple logistic regression analysis was used for 2 outcome variables of underweight and overweight.

Overall, 70.1% of the subjects were in the normal category of BMI (20 to 25), 13.4% were in the underweight category (< 20), and 16.5% were in the overweight category (> 25). Neither occlusal force nor masticatory performance was significantly correlated with BMI. However, when the lowest 20% of occlusal force and masticatory performance values were used as explanatory variables, multiple logistic regression analyses showed that being underweight was significantly associated with having lower masticatory performance (odds ratio = 2.0, P= .015). In addition, being overweight was significantly associated with lower occlusal force (odds ratio = 1.8, P = .013). There was no statistical difference in the underweight or overweight proportions as a function of either number of teeth or type of dentition.

Based on the results of this study, occlusal force and masticatory performance, rather than number of teeth or type of dentition, may play an important role in maintaining a normal BMI in independently living older Japanese people.