UMIN-ICDS Clinical Trial
| Unique ID issued by UMIN | UMIN000063491 |
|---|---|
| Receipt number | R000072659 |
| Scientific Title | Evaluation of the Effects of Different Types of Hot Spring Water on Human Skin: A Prospective Exploratory Interventional Study in Healthy Adults |
| Date of disclosure of the study information | 2026/11/01 |
| Last modified on | 2026/11/01 22:46:24 |
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Basic information
Public title
Evaluation of the Effects of Different Types of Hot Spring Water on Human Skin
Acronym
Evaluation of the Effects of Different Types of Hot Spring Water on Human Skin
Scientific Title
Evaluation of the Effects of Different Types of Hot Spring Water on Human Skin: A Prospective Exploratory Interventional Study in Healthy Adults
Scientific Title:Acronym
Evaluation of the Effects of Different Types of Hot Spring Water on Human Skin: A Prospective Exploratory Interventional Study in Healthy Adults
Region
| Japan |
Condition
Condition
Healthy adults (no specific disease targeted)
Classification by specialty
| Adult |
Classification by malignancy
Others
Genomic information
YES
Objectives
Narrative objectives1
To evaluate the effects of different types of hot spring water on skin function and the skin microbiota. Changes in skin function following repeated topical application and changes in the skin microbiota following bathing at hot spring sites will be explored and compared across water types.
Basic objectives2
Bio-availability
Basic objectives -Others
Trial characteristics_1
Exploratory
Trial characteristics_2
Pragmatic
Developmental phase
Not applicable
Assessment
Primary outcomes
Changes in skin function parameters (stratum corneum hydration, transepidermal water loss, skin pH, sebum level, viscoelasticity, skin color, and skin surface morphology) and skin microbiota composition before and after hot spring water exposure. Skin function is assessed at baseline and week 4 in the topical application study; microbiota are assessed before and after the seven-day bathing period in the on-site bathing study.
Key secondary outcomes
Microscopic image-based assessment of skin condition, changes in stratum corneum metabolites, changes in predicted microbial functions based on metagenomic prediction, and differences among hot spring water types.
Base
Study type
Interventional
Study design
Basic design
Parallel
Randomization
Non-randomized
Randomization unit
Blinding
Open -no one is blinded
Control
Placebo
Stratification
YES
Dynamic allocation
YES
Institution consideration
Institution is considered as a block.
Blocking
YES
Concealment
No need to know
Intervention
No. of arms
2
Purpose of intervention
Prevention
Type of intervention
| Behavior,custom |
Interventions/Control_1
Fifty-one healthy adults will be assigned to three groups (17 per group), each receiving one of three selected hot spring water types. Sterile gauze soaked with sterilized hot spring water containing a preservative will be applied to one inner forearm, and gauze soaked with similarly prepared placebo distilled water containing the same preservative will be applied to the other forearm once daily for 28 days. Skin measurements and sampling will be performed at baseline and week 4, following a 7-day washout period.
Interventions/Control_2
Fifty-one healthy adults will be allocated to three groups (17 per group), each assigned to one designated hot spring water type. Participants will bathe once daily for seven consecutive days, for a total of 20 minutes per session with breaks as needed. A 14-day washout period will precede bathing. Skin surface microbial samples from the inner forearm will be collected before and after the bathing period and analyzed by 16S rRNA gene sequencing.
Interventions/Control_3
Interventions/Control_4
Interventions/Control_5
Interventions/Control_6
Interventions/Control_7
Interventions/Control_8
Interventions/Control_9
Interventions/Control_10
Eligibility
Age-lower limit
| 20 | years-old | <= |
Age-upper limit
| 65 | years-old | >= |
Gender
Male and Female
Key inclusion criteria
Healthy Japanese men and women aged 20 to 65 years who understand the study and provide written informed consent, are able to participate in skin measurements and stratum corneum sampling or pre and post-bathing microbiota sampling, and can comply with study restrictions. The on-site bathing study primarily recruits Beppu residents and may recruit residents of Oita Prefecture if needed.
Key exclusion criteria
Exclusion criteria include eczema, wounds or marked inflammation of the inner forearm; severe dermatological or systemic disease; medications affecting outcomes; a history of allergy or contact dermatitis related to hot spring constituents, cosmetics or quasi-drugs; current or previous atopic dermatitis or an atopic predisposition; pregnancy or breastfeeding; inability to comply with restrictions on other hot spring use; or investigator judgment of ineligibility. For the topical application study, participation in other studies involving the inner forearm currently or within the preceding month is excluded; for the bathing study, participation in other clinical or human studies currently or within the preceding month is excluded.
Target sample size
102
Research contact person
Name of lead principal investigator
| 1st name | Takashi |
| Middle name | |
| Last name | Kobayashi |
Organization
Oita University
Division name
Faculty of Medicine
Zip code
879-5593
Address
1-1 Idaigaoka Hasama-machi Yufu Oita 879-5593 Japan
TEL
097-586-5702
takashik@oita-u.ac.jp
Public contact
Name of contact person
| 1st name | Takaaki |
| Middle name | |
| Last name | Yahiro |
Organization
Oita University
Division name
Faculty of Medicine
Zip code
879-5593
Address
1-1 Idaigaoka Hasama-machi Yufu Oita 879-5593 Japan
TEL
097-586-5712
Homepage URL
https://www.med.oita-u.ac.jp/idc/news/2025/news_250203.html
takaaki-816@oita-u.ac.jp
Sponsor or person
Institute
Oita University
Institute
Department
Personal name
Takashi Kobayashi
Funding Source
Organization
Beppu City
Organization
Division
Category of Funding Organization
Local Government
Nationality of Funding Organization
Japan
Other related organizations
Co-sponsor
MANDOM CORPORATION
Name of secondary funder(s)
IRB Contact (For public release)
Organization
Oita University
Address
1-1 Idaigaoka Hasama-machi Yufu Oita 879-5593 Japan
Tel
097-549-4411
takaaki-816@oita-u.ac.jp
Secondary IDs
Secondary IDs
NO
Study ID_1
Org. issuing International ID_1
Study ID_2
Org. issuing International ID_2
IND to MHLW
Institutions
Institutions
大分大学
Other administrative information
Date of disclosure of the study information
| 2026 | Year | 11 | Month | 01 | Day |
Related information
URL releasing protocol
Publication of results
Unpublished
Result
URL related to results and publications
Number of participants that the trial has enrolled
Results
Results date posted
Results Delayed
Results Delay Reason
Date of the first journal publication of results
Baseline Characteristics
Participant flow
Adverse events
Outcome measures
Plan to share IPD
IPD sharing Plan description
Progress
Recruitment status
Preinitiation
Date of protocol fixation
| 2026 | Year | 10 | Month | 01 | Day |
Date of IRB
Anticipated trial start date
| 2026 | Year | 10 | Month | 06 | Day |
Last follow-up date
| 2028 | Year | 03 | Month | 31 | Day |
Date of closure to data entry
| 2031 | Year | 03 | Month | 31 | Day |
Date trial data considered complete
Date analysis concluded
| 2031 | Year | 03 | Month | 31 | Day |
Other
Other related information
Management information
Registered date
| 2026 | Year | 11 | Month | 01 | Day |
Last modified on
| 2026 | Year | 11 | Month | 01 | Day |
Link to view the page
Value
https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000072659
