Influence of chewing time on salivary stress markers

We investigated the influence of chewing time on salivary stress markers.

Participants performed arithmetic calculations for 30min as stress loading, followed by chewing for 0, 5, 10, or 15min. All experiments finished at 25min after stress loading. With 0-min chewing, saliva was collected before stress loading (BS), immediately after stress loading (R0), and at 5, 10, 15, and 25min after stress loading (R5, 10, 15 and 25). With 5, 10, or 15min chewing, saliva was collected at BS and R0, immediately after chewing (Ch5, 10 and 15, respectively), and 25min after stress loading (Ch5R25, Ch10R25 and Ch15R25, respectively). Salivary alpha-amylase activity and cortisol levels were measured to evaluate stress. Change in stress markers between R0 and Ch5, 10 and 15 or R25, Ch5R25, Ch10R25 and Ch15R25 were calculated.

No significant differences were observed in rate of change in alpha-amylase activity among the chewing conditions. Rate of decrease in cortisol levels was significantly greater at 15-min chewing than at 5-min chewing. Rate of decrease in cortisol levels was significantly greater at 10 and 15-min chewing than at 0-min chewing.

The present results indicate that chewing time affects the reaction of the endocrine system to mental stress, and that continuous chewing for more than 10min is effective in reducing stress.