2.2. Study design
This sixteen-week trial was performed using a double-blind, placebo-controlled, parallel group design. Participants were asked to take 2 capsules per day as test foods for 16 weeks. The trial was started between January 25, 2018 and February 1, 2018. Participants visited Wakayama Medical University every 4 weeks (0, 4, 8, 12, and 16 weeks). The participants were asked to collect their saliva for 5 minutes with Salivette Cotton (Sarstedt, Nümbrecht, Germany) under an unstimulated condition. After collection of the saliva, all participants answered a questionnaire, 