Association Between Mean Chewing Count per Bite During Rice Ball Consumption and the Postprandial Salivary Secretory Immunoglobulin a Response in Healthy Adult Men: A Pilot Study

Background/Objectives: Mastication may influence oral mucosal immunity; however, its association with postprandial salivary secretory immunoglobulin A (s-IgA) dynamics remains unclear. This pilot study examined the association between mean chewing count per bite during rice ball consumption and the postprandial salivary s-IgA response in healthy men. Methods: Thirty-seven healthy adult men were enrolled. Mean chewing count per bite was analyzed continuously and secondarily in exploratory groups defined by the median (<30, n = 18; ≥30 chews/bite, n = 19). Unstimulated whole saliva was collected before, 0–5, 10–15, and 25–30 min after eating. Salivary s-IgA concentration, saliva weight, and s-IgA secretion rate were evaluated as absolute values and baseline ratios. Baseline-adjusted, repeated-measures, and sensitivity analyses were performed. Results: Mean chewing count per bite correlated positively with normalized salivary s-IgA concentration at 10–15 min (ρ = 0.347, p = 0.036) and 25–30 min (ρ = 0.352, p = 0.033), but these associations were attenuated after false discovery rate correction (q = 0.053 for both). Baseline salivary s-IgA was inversely associated with normalized responses. In exploratory group comparisons, normalized salivary s-IgA concentration was higher in the ≥30 chews/bite group at 10–15 and 25–30 min, whereas absolute s-IgA concentration, saliva weight, and s-IgA secretion rate did not differ between groups. Baseline-adjusted associations were not statistically significant. Conclusions: Higher mean chewing count per bite may be associated with greater relative postprandial salivary s-IgA responses in healthy adult men, but these findings are exploratory and should be interpreted cautiously.