Black Forest Cocoa Flavanol Supplementation and Health Trial

July 31, 2026 updated by: The Black Forest LLC
This randomized, double-blind, controlled clinical trial will evaluate the effects of daily cocoa flavanol supplementation on vascular and inflammatory biomarkers in healthy adult men aged 30 to 75 years. Participants will be randomized to receive either a cocoa flavanol supplement or a nutrient-matched low-flavanol control product for 4 to 8 weeks. The study will assess changes in inflammatory biomarkers, endothelial function, oxidative stress markers, vascular measurements, and circulating endothelial progenitor cell-related markers. Optional assessments include flow-mediated dilation and single-cell RNA sequencing of peripheral blood mononuclear cells to explore mechanistic biological responses to cocoa flavanol supplementation.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This is an early-phase, randomized, double-blind, controlled mechanistic clinical trial designed to evaluate the effects of daily cocoa flavanol supplementation on vascular biology and inflammatory biomarkers in healthy adults.

Participants aged 30 to 75 years will be randomized in a 1:1 ratio to receive either:

A cocoa flavanol supplement providing approximately 1,200 mg total flavanols daily, or A nutrient-matched low-flavanol cocoa-based control product.

The intervention period will last 4 to 8 weeks. Study products will be provided in identical packaging to maintain blinding.

Primary objectives include evaluating changes in biomarkers associated with endothelial function and systemic inflammation, including hs-CRP, IL-6, IL-1β, IL-10, VCAM-1, ICAM-1, E-selectin, TNF-α, CCL2, CCL4, and IFN-γ.

Secondary objectives include assessment of oxidative stress and vascular tone markers, blood pressure, pulse wave velocity, endothelial progenitor cell-related markers, endothelial microparticles, and nitric oxide-related biomarkers. Optional mechanistic assessments include flow-mediated dilation and single-cell RNA sequencing analyses in a participant subset.

Blood samples and vascular measurements will be obtained at baseline and at the end of the intervention period. The study is designed to explore physiologic and biomarker responses associated with cocoa flavanol supplementation in a healthy adult population

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
90

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Male participants aged 30 to 75 years.
  • Able and willing to provide written informed consent.
  • Generally healthy, as determined by medical history and screening assessments.
  • Willing and able to comply with all study procedures, including blood collection, daily study-product intake, and required study visits.
  • Willing to consume the assigned cocoa flavanol supplement or low-flavanol control product once daily for the duration of the study.
  • Willing to provide peripheral blood samples at baseline and at the end of the intervention.
  • Willing to maintain generally stable dietary, exercise, sleep, medication, and supplement habits during the study.
  • Willing to refrain from initiating new supplements, restrictive diets, fasting regimens, or major exercise programs during the study.
  • Not currently taking medications or supplements known to substantially affect vascular function, nitric oxide pathways, inflammation, oxidative stress, or coagulation, unless approved by the investigator.

Exclusion Criteria:

  • Female biological sex.
  • Younger than 30 years or older than 75 years.
  • Known cardiovascular, metabolic, renal, hepatic, inflammatory, or autoimmune disease, including coronary artery disease, diabetes mellitus, chronic kidney disease, chronic liver disease, rheumatoid arthritis, or another clinically significant inflammatory disorder.
  • Hypertension requiring prescription medication.
  • Active infection, acute illness, or other clinically significant medical condition at screening or baseline.
  • Current use of medications or supplements that may substantially affect vascular function, inflammatory biomarkers, nitric oxide pathways, oxidative stress, or coagulation, including chronic nonsteroidal anti-inflammatory drugs, systemic corticosteroids, anticoagulants, antiplatelet drugs, prescription immunomodulatory agents, phosphodiesterase-5 inhibitors, or high-dose antioxidant supplements, unless approved by the investigator.
  • Known allergy, hypersensitivity, or intolerance to cocoa, chocolate, cocoa flavanols, or any ingredient in either study product.
  • Gastrointestinal disease or condition that may interfere with digestion or absorption of the study product, including celiac disease, inflammatory bowel disease, active gastritis, or a clinically significant malabsorption disorder.
  • Current smoking or vaping of nicotine or cannabis products.
  • Major psychiatric illness, cognitive impairment, or another condition that may interfere with informed consent, adherence, or completion of study procedures.
  • Alcohol or drug abuse within the previous 12 months that, in the investigator's judgment, may affect participant safety or study adherence.
  • Participation in another interventional clinical study within 30 days before screening.
  • Plans to begin a new medication, supplement, restrictive diet, fasting regimen, or major exercise program during the study period.
  • Any condition or circumstance that, in the investigator's judgment, would increase participant risk, interfere with study procedures, compromise adherence, or affect interpretation of the study results.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Cocoa Flavanol Supplement
Participants will receive a daily cocoa flavanol powder supplement providing approximately 1,200 mg total cocoa flavanols per day for 4 to 8 weeks. The supplement will be administered orally once daily in a blinded fashion.
Dietary supplement: Cocoa Flavanol Supplement
A powdered cocoa flavanol dietary supplement administered orally once daily for 4 to 8 weeks. Each daily serving contains approximately 1,200 mg total cocoa flavanols in a 10 g powder formulation. The supplement is mixed with water or a non-alcoholic beverage and consumed in a blinded fashion.
Other Names:
  • Cocoa Flavanols
  • CF Supplement
Placebo Comparator: Low-Flavanol Control
Participants will receive a nutrient-matched low-flavanol cocoa-based powder containing less than 2% total flavanols for 4 to 8 weeks. The control product is designed to match the active supplement in appearance and administration while minimizing biologically active flavanol exposure.
Dietary supplement: Low-Flavanol Control Powder
A nutrient-matched low-flavanol cocoa-based powder administered orally once daily for 4 to 8 weeks. The control product contains less than 2% total flavanols and is designed to match the active supplement in appearance, taste, and administration while minimizing biologically active flavanol exposure.
Other Names:
  • Control Supplement
  • Low-Flavanol Cocoa Control

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change From Baseline in Circulating C-Reactive Protein Concentration
Time Frame: Baseline and Week 4
Circulating C-reactive protein will be measured in serum using a custom multiplex bead-based immunoassay. The outcome will be calculated for each participant as the Week 4 concentration minus the baseline concentration. Change from baseline will be compared between the cocoa flavanol supplementation group and the nutrient-matched low-flavanol control group.
Baseline and Week 4
Change From Baseline in Circulating Interleukin-6 Concentration
Time Frame: Baseline and Week 4
Circulating interleukin-6 will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating Vascular Endothelial Growth Factor A Concentration
Time Frame: Baseline and Week 4
Circulating vascular endothelial growth factor A will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating Endothelin-1 Concentration
Time Frame: Baseline and Week 4
Circulating endothelin-1 will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating Stromal Cell-Derived Factor 1 Alpha Concentration
Time Frame: Baseline and Week 4
Circulating stromal cell-derived factor 1 alpha, also known as SDF-1α or CXCL12, will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating E-Selectin Concentration
Time Frame: Baseline and Week 4
Circulating E-selectin will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating Intercellular Adhesion Molecule-1 Concentration
Time Frame: Baseline and Week 4
Circulating intercellular adhesion molecule-1 will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating Vascular Cell Adhesion Molecule-1 Concentration
Time Frame: Baseline and Week 4
Circulating vascular cell adhesion molecule-1 will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating C-C Motif Chemokine Ligand 4 Concentration
Time Frame: Baseline and Week 4
Circulating C-C motif chemokine ligand 4, also known as CCL4, will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating C-C Motif Chemokine Ligand 2 Concentration
Time Frame: Baseline and Week 4
Circulating C-C motif chemokine ligand 2, also known as CCL2, will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating Interferon-Gamma Concentration
Time Frame: Baseline and Week 4
Circulating interferon-gamma will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating Tumor Necrosis Factor-Alpha Concentration
Time Frame: Baseline and Week 4
Circulating tumor necrosis factor-alpha will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating Interleukin-10 Concentration
Time Frame: Baseline and Week 4
Circulating interleukin-10 will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating Interleukin-1 Beta Concentration
Time Frame: Baseline and Week 4
Circulating interleukin-1 beta will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4
Change From Baseline in Circulating Leptin Concentration
Time Frame: Baseline and Week 4
Circulating leptin will be measured in serum or plasma using a custom multiplex bead-based immunoassay. The outcome will be calculated as the Week 4 concentration minus the baseline concentration and compared between treatment groups.
Baseline and Week 4

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change From Baseline in Circulating Endothelial Progenitor Cell Frequency
Time Frame: Baseline and 4 weeks after the first dose
Circulating endothelial progenitor cells will be quantified in peripheral blood by flow cytometry. The outcome will be calculated as the end-of-intervention value minus the baseline value and compared between the cocoa flavanol supplementation group and the nutrient-matched low-flavanol control group.
Baseline and 4 weeks after the first dose
Change From Baseline in Circulating Nitric Oxide Metabolite Concentration
Time Frame: Baseline and Week 4
Circulating nitric oxide metabolites will be measured in serum or plasma using the RayBiotech MA-NO metabolism assay. The outcome will be calculated for each participant as the Week 4 value minus the baseline value. Change from baseline will be compared between the cocoa flavanol supplementation group and the nutrient-matched low-flavanol control group.
Baseline and Week 4

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change From Baseline in Peripheral Blood Mononuclear Cell-Type Abundance by Single-Cell RNA Sequencing
Time Frame: Baseline and Week 4
As an exploratory pilot analysis, single-cell RNA sequencing will be performed on peripheral blood mononuclear cells collected at baseline and Week 4 from a subset of participants. For each identified immune-cell population, cell-type abundance will be calculated as the proportion of quality-controlled cells assigned to that cell type. Exploratory changes from baseline will be evaluated within participants and compared between the cocoa flavanol supplementation and nutrient-matched low-flavanol control groups. This pilot analysis is not powered for confirmatory hypothesis testing.
Baseline and Week 4
Exploratory Change From Baseline in Single-Cell Gene-Expression Pathway Scores
Time Frame: Baseline and Week 4
As an exploratory pilot analysis, single-cell RNA sequencing of peripheral blood mononuclear cells will be used to evaluate cell-type-specific transcriptional changes associated with inflammation, angiogenesis, oxidative stress, vascular repair, and progenitor-cell activity. Prespecified gene-expression pathway scores will be calculated within relevant cell populations. Exploratory changes from baseline to Week 4 will be evaluated within participants and compared between treatment groups. This pilot analysis is not powered for confirmatory hypothesis testing.
Baseline and Week 4

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
The Black Forest LLC

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Shlomi Brielle, PhD, The Black Forest LLC

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
August 15, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
July 31, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 31, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
August 5, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 5, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 31, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • BF-CF-HEALTH-001
  • Pro00092276 (Other Identifier: Advarra IRB)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Only aggregate, de-identified study results are planned for publication. Individual participant-level data will not be shared.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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