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NCT Number: NCT07747714

Black Forest Cocoa Flavanol Supplementation and Health Trial

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.

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Key information

Conditions

Endothelial Function Inflamation Oxidative Stress Vascular Health

Age range

30 year–75 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Black Forest Supplements (The Black Forest LLC), Miami, Florida, United States

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About this study

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

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

Cocoa Flavanol Supplement

Dietary 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

Low-Flavanol Control Powder

Dietary Supplement

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

Primary outcomes

  1. 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.

  2. 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.

  3. 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.

  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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

Secondary outcomes

  1. 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.

  2. 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.

Other outcomes

  1. 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.

  2. 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.

Study contacts

Contact information is provided by the study sponsor or research team.

Shlomi Brielle, PhD

CONTACT

[email protected]

‪(617) 744-9534‬

Sponsors and collaborators

Lead sponsor

The Black Forest LLC

Industry

Registry information

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Aug 5, 2026
Registry last updated
Aug 5, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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