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Comparative Study of Olfactory Training in Patients with Idiopathic Olfactory Dysfunction

Comparison of Olfactory Training in Olfactory Impaired Cases with Unknown Cause

Shiga Hideaki

Kanazawa Medical University Hospital

1-1,Daigaku,Uchinada,Kahoku,Ishikawa

shigah@kanazawa-med.ac.jp

Shiga Hideaki

Kanazawa Medical University

1-1,Daigaku,Uchinada,Kahoku,Ishikawa

+81-76-218-8147

shigah@kanazawa-med.ac.jp

Recruiting

Mar. 24, 2026

Interventional

randomized controlled trial

open(masking not used)

active control

parallel assignment

treatment purpose

1) Idiopathic olfactory dysfunction.
2) No apparent cause in medical history, such as common cold (including COVID-19), head trauma, or dementia.
3) No abnormal findings in the nasal sinuses on nasal fiberoptic or sinus CT.
4) No significant intracranial cerebral atrophy, cerebrovascular disease, or brain tumor on head MRI.
5) Average of odor recognition threshold in T&T olfactometry of 2.6 to 4.0 (moderately depressed) or 4.2 to 5.4 (severely depressed).
6) Age is 50 years or older.
7) Gender is unspecified.
8) Outpatients.
9) Independent in daily activities.
10) Written informed consent has been obtained from the patient, freely given after a sufficient explanation of the study and before participation.

1) Patients with olfactory dysfunction for more than 3 years.
2) Patients who received olfactory stimulation therapy within 1 month prior to the start of the study.
3) Patients taking oral steroids, nasal steroids, zinc preparations, vitamin B12 preparations or Chinese herbal preparations.
4) Patients with a threshold value exceeding 8 dB in either the right or left tympanic nerve area in an electrical taste test.
5) Patients with a history of airway hypersensitivity disease such as poorly controlled asthma.
6) Patients with a history of food allergy, or with a positive test result for allergens that cause food allergy in allergy test View 39.
7) Patients suffering from or with a history of serious internal organ diseases.
8) Patients who are deemed inappropriate as study participants by the principal investigator or a physician in charge of the research.

Both

Idiopathic olfactory dysfunction

Study participants will be randomly assigned to either the soup food group or the olfactory training kit group at the time of enrollment.
Participants in the soup food group will take the soup food once a day, either between meals or before meals.
Participants in the olfactory training group will perform olfactory training twice a day.
At a follow-up visit 12 weeks after the start of the study, if the study participants wish to continue their participation in the study, they will receive an additional 12-week supply of soup foods or olfactory training kits.

Idiopathic olfactory dysfunction

olfactory training

D000857

D000094562

Average of odor recognition threshold in T&T olfactometry

Number of correct answers to the card-based olfactory identification ability test (Open Essence), results of the daily smell questionnaire, questionnaires on diet and health status, olfactory stimulus/meal record card, and percentage of adverse event occurrence.

+81-76-218-8346

Nov. 27, 2025

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