An interventional study of High-flavanol cocoa powder and Low-flavanol cocoa powder in Healthy, sponsored by University of Birmingham. Completed at 1 site in United Kingdom. Open to female participants aged 18 Years to 26 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-07.
Sponsored by University of Birmingham · Not applicable, Interventional, and Treatment
The aim of this project is to examine whether flavonoids, which are small molecules naturally present in cocoa, as well as fruits and vegetables such as berries, tea, citrus fruits, apple (typically responsible for giving these foods their strong colours), can be used to protect the human vascular system. Impaired vascular function, as determined by measuring vasodilator responses to various everyday stimuli, can be linked to elevated blood pressure (hypertension) and prevalence of cardiovascular disease. Vascular response to mental stress in particular have been shown to be associated with future risk of cardiovascular disease. Findings from this study could have implications for effective prevention of cardiovascular events in groups with increased cardiovascular risk, such as South Asians and in particular, South Asian women.
Psychological stress is linked to cardiovascular health, specifically there is evidence of increased risk of cardiovascular events following episodes of psychological stress, suggesting a vulnerability of the cardiovascular system to the experience of stress.
Individuals of South Asian ethnicity are at higher risk of CVD but also have higher incidence of stress and mood disorders. SA women, in particular, have higher incidence of mental disorders and depression, compared to age-matched WE women, suggesting that this may be a particular vulnerable group.
Flavanols are polyphenolic molecules abundant in cocoa, apples, berries and tea, which have been shown to exert both acute and chronic benefits in the vascular system, by improving conduit artery endothelial function and blood pressure.
However, the effect of flavonoid-rich interventions in ethnic groups at higher risk of CVD, such as South Asians, have not been studied. Intake of flavonoid-rich foods in this population may be able to protect vascular function, particularly in the context of psychological stress.
In this preliminary acute study (randomised, placebo-controlled, double-blind, cross-over intervention) in SA and WE women we assess the effect of an acute cocoa flavanol intervention on the microvascular and cardiovascular responses to acute mental stress. We further compare the impact of flavanols on microvascular responses between women who showed vasodilation in comparison to women that exhibit vasoconstriction during mental stress.
806 studies on the registry are indexed under Stress, Psychological; 131 are open to participants now.
This study's enrollment of 23 is below the median of 84 across 651 interventional studies indexed under Stress, Psychological.
Browse Stress, Psychological studies →University of Birmingham is the lead sponsor of 182 studies on the registry; 29 are open to participants now.
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Exclusion Criteria:
12 g of fat-reduced natural cocoa powder containing 695 mg of total flavanols, including 150 mg (-)-epicatechin
Dietary Supplement: High-flavanol cocoa powder
12 g of fat-reduced alkalized cocoa powder containing 5.6 mg of total flavanols
Dietary Supplement: Low-flavanol cocoa powder
12 g of fat-reduced natural cocoa powder containing 695 mg of total flavanols, including 150 mg (-)-epicatechin
12 g of fat-reduced alkalized cocoa powder containing 5.6 mg of total flavanols
Forearm oxygen saturation (NIRS) during mental stress (SO2)
Forearm levels of tissue saturation (SO2) will be assessed by functional Near-Infrared Spectroscopy (fNIRS). The NIRS device measures changes in chromophore concentrations of oxyhaemoglobin (O2Hb) and deoxyhaemoglobin (HHb), providing depth-resolved measures of total tissue oxygen saturation: oxyHb /(oxyHb+deoxyHb)
Time frame: Change from pre-intervention baseline to 1. 5 hours post-intervention (during mental stress)
Forearm total haemoglobin (NIRS) during mental stress (total Hb)
Forearm levels of tissue saturation (totalHb) will be assessed by functional Near-Infrared Spectroscopy (fNIRS). The NIRS device measures changes in chromophore concentrations of oxyhaemoglobin (O2Hb) and deoxyhaemoglobin (HHb), providing depth-resolved measures of changes in total haemoglobin, which is an index of tissue perfusion/blood flow: oxyHb+deoxyHb
Time frame: Change from pre-intervention to 1.5 hours post-intervention (during mental stress)
Beat-to-beat systolic blood pressure (SBP)
Beat-to-beat systolic blood pressure (SBP) will be measured using a Finometer (mmHg)
Time frame: Change from pre-intervention baseline to 1.5 hour post-intervention (during mental stress)
Beat-to-beat diastolic blood pressure (DBP)
Beat-to-beat diastolic blood pressure (DBP) will be measured using a Finometer (mmHg)
Time frame: Change from pre-intervention to 1. 5 hours post-intervention (during mental stress)
Beat-to-beat mean arterial pressure (MAP)
Beat-to-beat mean arterial pressure (MAP) will be estimated from beat to beat diastolic and systolic blood pressure
Time frame: Change from pre-intervention to 1. 5 hours post-intervention (during mental stress
Forearm Vascular Conductance index (FVC) during mental stress
Forearm levels of vascular conductance (FVC) will be assessed by functional Near-Infrared Spectroscopy (fNIRS). The NIRS device measures changes in chromophore concentrations of oxyhaemoglobin (O2Hb) and deoxyhaemoglobin (HHb), which is used to estimate totalHb. Pulsatile (beat to beat) Arterial Blood pressure will be monitored using a Finometer® MIDI (Finapres Medical Systems) during mental stress. FVC index will be estimated by dividing ∆totalHb by Mean Arterial Blood pressure
Time frame: Change from pre-intervention to 1. 5 hours post-intervention (during mental stress)
Heart rate (HR) during mental stress
Heart rate (HR, bpm) is assessed using an electrocardiogram.
Time frame: Change from pre-intervention to 1. 5 hours post-intervention (during mental stress)
Resting Diastolic Blood Pressure (DBP)
Resting diastolic blood pressure (mmHg) will be measured using an automated oscillometric blood pressure monitor, with a cuff attached to the right upper arm, following at least 10 minutes rest.
Time frame: Change from pre-intervention baseline to 1.5 hours post intervention
Brachial Systolic Blood Pressure (SBP)
Resting systolic blood pressure (mmHg) will be measured using an automated oscillometric blood pressure monitor, with a cuff attached to the right upper arm, following at least 10 minutes rest.
Time frame: Change from pre-intervention baseline to 1.5 hours post intervention
Vasoconstriction/ Vasodilatory status of individuals during mental stress
Determined by a positive FVC index (vasodilator) or negative FVC index (vasoconstrictor) in the control group
Time frame: Pre-intervention (control)
Forearm microvascular response to stress in vasoconstrictor vs vasodilator participants
Planned sub-analysis comparing physiological measures described between those participants who vasodilate in response to stress (healthy response) and those who vasoconstrict in response to stress (unhealthy response). Physiological measures during mental stress task will include Heart Rate, Beat-to-beat diastolic and systolic blood pressure, Forearm Tissue Saturation (SO2, NIRS), Forearm Total Haemoglobin (total Hb, NIRS) and Forearm Vascular Conductance (FVC index)
Time frame: Change from pre-intervention baseline to 1.5 hours post intervention
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Plan to share: No
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Aug 2026. You cannot join it, but the record below documents what was studied.
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