Effects of Capsaicin on Masticatory and Swallowing Function.

Introduction: Recent studies have shown that capsaicin improves the pharyngeal swallowing reflex. However, the mechanism by which capsaicin alters mastication and oesophageal function remains unclear. This study aimed to investigate the effects of capsaicin on masticatory and oesophageal function.

Materials And Methods: Participants were 12 healthy individuals (7 men, 5 women: aged 31.5 ± 3.0 years). The participants ingested five rice cakes without capsaicin and then five rice cakes containing capsaicin. Total mastication frequency, total mastication time, and mastication rate were measured. Pharyngeal and upper oesophageal sphincter (UES) parameters were evaluated using high-resolution manometry (HRM). The masticatory and HRM parameters were compared between the ingestion of capsaicin-containing and non-capsaicin containing rice cakes.

Results: The total mastication frequency and total mastication time(s) for capsaicin ingestion were significantly smaller (20.3 ± 9.4 vs. 22.4 ± 7.4; p = 0.011) and shorter (14.2 ± 7.0 vs. 15.4 ± 5.6; p = 0.038), respectively, than those for non-capsaicin ingestion. Comparison of the HRM parameters revealed significantly higher hypopharyngeal contractile integral (mmHg-s-cm) (56.6 ± 40.7 vs. 49.7 ± 43.6; p = 0.016) and proximal oesophageal contractile integral (mmHg-s-cm) (492.3 ± 292.64 vs. 381.2 ± 266; p < 0.001), significantly shorter UES basal pressure (mmHg) (93.6 ± 37.8 vs. 114.5 ± 43.4; p < 0.001), and significantly longer UES relaxation time (ms) (486.7 ± 90.7 vs. 431.2 ± 82.3; p < 0.001) for capsaicin ingestion than for non-capsaicin ingestion.

Conclusions: Decreased mastication frequency and time, increased hypopharyngeal and proximal oesophageal contractile integral, and prolonged UES opening time with capsaicin ingestion suggests that capsaicin improves oral, pharyngeal and oesophageal phases of swallowing.