Sampling method
RECRUITMENT
At the time of recruitment, Day 0, and Week 3, the subjects who underwent sampling in the morning stopped drinking and eating after breakfast, and those who underwent sampling in the afternoon stopped drinking and eating after lunch (drinking water was permitted). The sampling time was between 10:00 and 17:00 on Day 0 and at Week 3. The subjects stopped drinking water, gargling and smoking for 30 min before sampling. At Day 1 and Week 1, the subjects underwent sampling immediately after waking up. All saliva and tongue coating samples were collected using an Intraoral Flora DNA/RNA Sampling Kit (saliva: OMNIgene®/ORAL OM‐505; DNA Genotek; tongue: OMNIgene®/ORAL OMR‐120; DNA Genotek) and stored at 15–30°C (saliva) or 15–25°C (tongue). All collected samples were sent to Shizuoka Innovation Center (Shizuoka, Japan), Sunstar Inc.