The impact of masticatory ability as evaluated by salivary flow rates on obesity in japanese: The Toon health study

Objective This study examined the associations of masticatory ability evaluated by chewing-gum-stimulated salivary flow rate with anthropometric indices among a general Japanese population. Methods In total, 921 Japanese men and women aged 30-79 years participated in this cross-sectional study. Saliva production was stimulated by 5 min of gum chewing, then collected; salivary flow rate was calculated as g/min. Overweight, abdominal obesity in terms of waist circumference (WC), and waist-hip ratio (WHR), and elevated skinfold thickness statuses were determined. Results The multivariable odds ratio and 95% confidence intervals of overweight, abdominal obesity (WC, WHR), and elevated skinfold thickness status for highest vs. lowest quartile of salivary flow rate were 0.59 (0.37-0.95, P for trend=0.02), 0.65 (0.43-0.98, P=0.03), 0.54 (0.35-0.83, P<0.01), and 0.61 (0.39-0.96, P<0.01), respectively. The linear trends of multivariable-adjusted means of BMI, WC, WHR, and skinfold thickness according to quartiles of salivary flow rate did not vary after stratification by overweight status. Conclusions Higher stimulated salivary flow rate, a surrogate marker for mastication ability, was associated with lower prevalence of overweight, abdominal obesity (whether WC- or WHR-defined), and elevated skinfold thickness among the general Japanese population.