Related Experiment Video
Updated: Jan 20, 2026
Adapting Human Videofluoroscopic Swallow Study Methods to Detect and Characterize Dysphagia in Murine Disease Models
Published on: March 1, 2015
Inhaled hinoki cypress essential oil improves saliva secretion and swallowing function in older adults with
Yoichiro Aoyagi1, Ryo Furuya2, Masaki Kawasaki2
1Department of Rehabilitation Medicine, Graduate School of Medicine, Nippon Medical School.
Background:
Olfactory stimulation with hinoki cypress essential oil reportedly reduces stress hormones and enhances parasympathetic activity, which may in turn increase salivary secretion and facilitate swallowing. However, its effects on swallowing in older adults with dysphagia remain unclear.
Methods:
In this placebo-controlled, single-blind, randomized crossover study, older adults with dysphagia (Food Intake Level Scale ≤9) underwent 5-minute olfactory stimulation with hinoki cypress essential oil or rice oil (placebo) in two sessions one week apart. Repetitive saliva swallowing test (RSST), 3 mL modified water swallowing test (MWST), 30 mL water swallowing test (WST), saliva secretion for 5 minutes, blood pressure, and heart rate were measured before and after each stimulation. Changes from pre- to post-stimulation were compared within each condition and between conditions using Wilcoxon's signed-rank test.
Results:
Thirty-four participants (47% women; 80 ± 10 years) were included. Hinoki cypress essential oil significantly improved RSST (median difference 0.5, 95% CI 0.0-1.0; p = 0.004), MWST (0.5, 95% CI 0.0-1.0; p = 0.003), and saliva secretion (1.0 mL, 95% CI 0.5-2.0; p = 0.002), whereas placebo produced no significant change (all p > 0.05). Improvements in swallowing function were greater with hinoki than with placebo. The increase in saliva secretion following hinoki stimulation was not associated with changes in RSST or MWST scores.
Conclusions:
Brief olfactory stimulation with hinoki cypress essential oil improved swallowing function and increased saliva secretion in older adults with dysphagia compared with placebo in a randomized crossover design. Hinoki cypress essential oil inhalation may represent a simple, noninvasive adjunctive strategy for dysphagia management, warranting confirmation in larger and longer trials.
Trial Registration:
This study was registered in the UMIN Clinical Trials Registry (UMIN-CTR) under registration number UMIN000053271.
Related Concept Videos
08:32Adapting Human Videofluoroscopic Swallow Study Methods to Detect and Characterize Dysphagia in Murine Disease Models
14:13Coordinate Mapping of Hyolaryngeal Mechanics in Swallowing
09:07The Effect of the Application of Thyme Essential Oil on Microbial Load During Meat Drying
04:00Studying the Effects of Inhaled Environmental Pollutants on Olfactory Function in Mice
06:25Stereoacuity Improvement using Random-Dot Video Games
01:25Compounds Essential to Human Function
Inorganic Compounds Essential to Human Functioning
Inorganic compounds essential to human functioning include water, salts, acids, and bases. These compounds are inorganic, i.e., they do not have a carbon-hydrogen bond. Water...