2.5. Intervention
throat, fever
The participants fasted for 2 h before the start of the treatment periods. Before commencement, a thorough health assessment was conducted on the participants, ensuring the absence of any subjective symptoms affecting the oral and throat regions, as well as the absence of fever (<37.5 °C). Following this confirmation, the participants drank water to wash their mouths and spent an hour within a general hydrothermal environment (20 °C, 60% relative humidity (RH)) to acclimatize. Subsequently, baseline evaluations were performed. Then, they orally ingested the test food and were exposed to low humidity (20 °C, 20% RH) representative of the indoor environment during winter in Japan [