Sex Differences in the Association Between Masticatory Function and Sarcopenia Components: The Shizuoka Study

Background/Objectives: Low masticatory function has been proposed as a risk factor for sarcopenia. This study investigated its potential association with body composition and physical performance in community-dwelling older adults. Methods: Participants included adults aged ≥65 years (643 men; 797 women) who volunteered for a longitudinal cohort study. Masticatory function was objectively assessed using gummy jelly and subjectively evaluated via a structured questionnaire. The skeletal muscle mass, body mass index, waist circumference, handgrip strength, gait speed, and five-time chair-stand test were assessed. Results: Objectively measured masticatory function was classified as low (12.6%), moderate (38.0%), or high (49.4%). In men, masticatory function was significantly associated with skeletal muscle mass index (low, moderate, and high: 7.4, 7.7, and 7.7 kg/m²; p = 0.005), handgrip strength (31.8, 34.2, and 35.5 kg; p < 0.001), and gait speed (1.3, 1.4, and 1.4 m/s; p = 0.003). In women, low masticatory function was linked to a higher body mass index (22.9, 22.0, and 21.9 kg/m²; p = 0.028) and waist circumference (82.9, 80.8, and 80.4 cm; p = 0.041). Moreover, these significant associations persisted after adjusting for covariates. Discrepancies were observed between objective and subjective measures of masticatory function, with approximately 40% of participants showing low objective masticatory function, perceiving their chewing ability as normal. Subjective masticatory function exhibited no significant associations with anthropometric measures or sarcopenia components. Conclusions: In men, objectively measured low masticatory function was associated with reduced skeletal muscle mass and poor physical performance; in women, it was linked to higher body mass index.