Healthy Adults; Hematopoietic System; CaffeineCaffeineHSCNCT07193264
Impact of Chronic and Acute Caffeine Intake on the Hematopoietic System
A study testing Caffeine (200 mg) in people with Healthy Adults; Hematopoietic System; Caffeine, run by Jasmin Rettkowski at 2 sites in Switzerland.
Trial summary
This study investigates how caffeine intake affects blood stem and progenitor cells in healthy adults. The trial will compare people who regularly consume caffeine with those who consume very little or none. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Healthy Adults; Hematopoietic System; Caffeine
- What is being tested?
- Caffeine (200 mg)
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 100 participants
- Where
- 2 sitesSwitzerland
- Study dates
- 5 Nov 2025to Jun 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Able to give consent.
- Healthy adults aged ≥ 18 years.
- Regular caffeine consumers (≥1 coffee cup/day or ≥1 energy drink/day) or non-consumers (≤1 cup/month and ≤1 energy drink/month) for at least 6 months.
- Willingness to comply with fasting requirements and study procedures.
Who cannot join
- Chronic illnesses or medication use affecting metabolism, including metabolic disorders (e.g., diabetes, thyroid dysfunction, metabolic syndrome).
- Personal history of cancer.
- Personal history of hematological disorders.
- History of radiation therapy.
- Known caffeine hypersensitivity or intolerance.
- Known immunosuppression.
Trial locations and contacts
2 sites in 1 country. Contact the study team or a site near you to ask about taking part.
Switzerland2 sites, 2 recruiting
- Not yet recruiting
ETH GLC
Zurich, Canton of Zurich, 8006
Jasmin Rettkowski, +41 77 236 88 07, dietary.trials@ethz.ch
Nina Cabezas-Wallscheid, nina.cabezas@hest.ethz.ch
- Recruiting
ETH GLC
Zurich, Canton of Zurich, 8006
Rettkowski, +41 77 236 88 07, dietary.trials@ethz.ch
About this study
Official title: CaffeineHSC - Effect of Chronic Caffeine Consumption and Acute Caffeine Administration on the Hematopoietic System
This study investigates how caffeine intake affects blood stem and progenitor cells in healthy adults.
The trial will compare people who regularly consume caffeine with those who consume very little or none. All participants will receive a single 200 mg caffeine tablet (similar to one cup of coffee) under fasting conditions. Blood samples will be collected before and three hours after caffeine intake.
The study will assess whether caffeine influences the mobilization of blood stem and progenitor cells from the bone marrow into the bloodstream. It will also examine the effects of caffeine on the function, gene activity, and metabolism of blood cells.
- Being tested
- Caffeine (200 mg)
- Keywords
- Caffeine consumption, caffeine, Hematopoietic Stem Cells, Hematopoietic Stem and Progenitor Cells, Effect of caffeine on blood system, Effect of caffeine on hematopoietic system
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Caffeine (200 mg)Other
Participants receive a single oral dose of 200 mg caffeine under fasting conditions. Blood samples are collected before and three hours after intake to evaluate effects on hematopoietic stem and progenitor cells, including mobilization, function, gene expression, and metabolism.
| Study group | Role | What they receive |
|---|---|---|
| Caffeine intervention | Experimental | 200mg Caffeine Receives: Other: Caffeine (200 mg) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Mobilization of hematopoietic stem and progenitor cells
The change in the numbers of mobilized HSPCs (defined as CD34+ cells) [cells/ml] in blood (measured by flow cytometry) from baseline to three hours after intake of a single oral dose of 200mg caffeine in habitual caffeine consumers versus non-caffeine consumers.
Measured: From baseline to three hours after caffeine intake
Mobilization of hematopoietic stem and progenitor cells
The change in the relative abundance of HSPCs [% HSPCs of total PBMCs] in blood (measured by flow cytometry) from baseline to three hours after intake of a single oral dose of 200mg caffeine in habitual caffeine consumers versus non-caffeine consumers.
Measured: From baseline to three hours after caffeine intake
Secondary outcomes (6)
Functional alterations in CD34+ peripheral blood cells
Functional alterations in CD34+ PB cells: self-renewal [number of colonies] assessed via colony-forming unit assay.
Measured: From baseline to three hours after caffeine intake
Functional alterations in CD34+ peripheral blood cells
Functional alterations in CD34+ PB cells: single HSPC proliferation [number of cell divisions within 72h] assessed via single HSC proliferation assay.
Measured: From baseline to three hours after caffeine intake
Transcriptional changes in CD34+ cells
Transcriptional changes in CD34+ cells [log2 fold change in gene expression and DEG count] assessed via single-cell RNA sequencing.
Measured: From baseline to three hours after caffeine intake
Relative metabolite abundance
Relative metabolite abundance [arbitrary units based on peak area or height in LC-MS] in plasma and intracellularly in isolated CD34+ cells.
Measured: From baseline to three hours after caffeine intake
Change in the numbers of peripheral blood cells
The change in the numbers of PB cells [cells/ml], including B cells, T cells, myeloid cells in blood, and relative, and measured by flow cytometry
Measured: From baseline to three hours after caffeine intake
Change in the numbers of peripheral blood cells
The change in relative abundance of PB cells [% cell type of total PBMCs] including B cells, T cells, myeloid cells in blood, and measured by flow cytometry
Measured: From baseline to three hours after caffeine intake
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 Sep 2025
- Study start5 Nov 2025
- Primary completionDec 2027 (estimated)
- Study completionJun 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Healthy Adults; Hematopoietic System; CaffeineStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- This is a single-group, open-label study in which all participants receive a single oral dose of 200 mg caffeine under fasting conditions. Blood samples are collected before and three hours after caffeine intake to assess mobilization, function, gene expression, and metabolic profile of hematopoietic stem and progenitor cells.
- Masking
- None (open label)
- Enrolment
- 100 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Jasmin Rettkowski
- Sponsor type
- University, hospital or other
- Collaborators
- ETH Zurich, Laboratory of Stem Cell Biology and Ageing, ETH Zurich, Prof. Nina Cabezas-Wallscheid, Prof. Dr. Nina Cabezas-Wallscheid, ETH Zurich
- Responsible party
- Sponsor-investigator, Jasmin Rettkowski, ETH Zurich
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07193264
- Sponsor's protocol ID
- 2025-00914
- Other IDs
- 2025
- Acronym
- CaffeineHSC
- Status last verified
- Nov 2025
- First submitted
- 18 Sep 2025
- Last updated
- 6 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes
Study at a glance
From the registry record, last updated by the sponsor on 6 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- CaffeineHSC - Effect of Chronic Caffeine Consumption and Acute Caffeine Administration on the Hematopoietic System
- ClinicalTrials.gov ID
- NCT07193264
- Acronym / sponsor ID
- CaffeineHSC / 2025-00914
- Keywords
- Caffeine consumption, caffeine, Hematopoietic Stem Cells, Hematopoietic Stem and Progenitor Cells, Effect of caffeine on blood system, Effect of caffeine on hematopoietic system
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 100 participants (estimated)
- Lead sponsor
- Jasmin RettkowskiUniversity, hospital or other
- Collaborators
- ETH Zurich, Laboratory of Stem Cell Biology and Ageing, ETH Zurich, Prof. Nina Cabezas-Wallscheid, Prof. Dr. Nina Cabezas-Wallscheid, ETH Zurich
- Study start
- 5 Nov 2025 (actual)
- Primary completion
- Dec 2027 (estimated)
- Study completion
- Jun 2028 (estimated)
- First posted
- 25 Sep 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study investigates how caffeine intake affects blood stem and progenitor cells in healthy adults.
The trial will compare people who regularly consume caffeine with those who consume very little or none. All participants will receive a single 200 mg caffeine tablet (similar to one cup of coffee) under fasting conditions. Blood samples will be collected before and three hours after caffeine intake.
The study will assess whether caffeine influences the mobilization of blood stem and progenitor cells from the bone marrow into the bloodstream. It will also examine the effects of caffeine on the function, gene activity, and metabolism of blood cells.
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- This is a single-group, open-label study in which all participants receive a single oral dose of 200 mg caffeine under fasting conditions. Blood samples are collected before and three hours after caffeine intake to assess mobilization, function, gene expression, and metabolic profile of hematopoietic stem and progenitor cells.
| Arm | Type | Receives |
|---|---|---|
| Caffeine intervention | Experimental | Other: Caffeine (200 mg)200mg Caffeine |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Able to give consent.
- Healthy adults aged ≥ 18 years.
- Regular caffeine consumers (≥1 coffee cup/day or ≥1 energy drink/day) or non-consumers (≤1 cup/month and ≤1 energy drink/month) for at least 6 months.
- Willingness to comply with fasting requirements and study procedures.
Key exclusion criteria (6 listed)
- Chronic illnesses or medication use affecting metabolism, including metabolic disorders (e.g., diabetes, thyroid dysfunction, metabolic syndrome).
- Personal history of cancer.
- Personal history of hematological disorders.
- History of radiation therapy.
- Known caffeine hypersensitivity or intolerance.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Caffeine (200 mg)Participants receive a single oral dose of 200 mg caffeine under fasting conditions. Blood samples are collected before and three hours after intake to evaluate effects on hematopoietic stem and progenitor cells, including mobilization, function, gene expression, and metabolism. | Other | Caffeine intervention |
Primary outcome
Mobilization of hematopoietic stem and progenitor cells
Time frame: From baseline to three hours after caffeine intake
The change in the numbers of mobilized HSPCs (defined as CD34+ cells) [cells/ml] in blood (measured by flow cytometry) from baseline to three hours after intake of a single oral dose of 200mg caffeine in habitual caffeine consumers versus non-caffeine consumers.
Mobilization of hematopoietic stem and progenitor cells
Time frame: From baseline to three hours after caffeine intake
The change in the relative abundance of HSPCs [% HSPCs of total PBMCs] in blood (measured by flow cytometry) from baseline to three hours after intake of a single oral dose of 200mg caffeine in habitual caffeine consumers versus non-caffeine consumers.
6 secondary outcomes
Functional alterations in CD34+ peripheral blood cells
Time frame: From baseline to three hours after caffeine intake
Functional alterations in CD34+ peripheral blood cells
Time frame: From baseline to three hours after caffeine intake
Transcriptional changes in CD34+ cells
Time frame: From baseline to three hours after caffeine intake
Relative metabolite abundance
Time frame: From baseline to three hours after caffeine intake
Change in the numbers of peripheral blood cells
Time frame: From baseline to three hours after caffeine intake
Change in the numbers of peripheral blood cells
Time frame: From baseline to three hours after caffeine intake
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Jul 2026.
- Individual participant dataSharing planned: Yes
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Caffeine (200 mg) in people with Healthy Adults; Hematopoietic System; Caffeine, run by Jasmin Rettkowski at 2 sites in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 6 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Each site lists its own contact: choose the nearest one under Trial locations. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Mobilization of hematopoietic stem and progenitor cells (time frame: From baseline to three hours after caffeine intake). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Jul 2026; AzTrials last refreshed its copy on 8 Nov 2026.