Clinical trial NCT06923722: De-stressing the Brain: Can Eating Grapes During Periods of Mental Stress Protect Brain and Vascular Health in Young Adults
Official title: A Placebo-controlled, Randomized, Double-masked, Cross-over Acute Intervention Study Investigating the Effects of Grape Polyphenols on Cerebral Oxygenation, Cognitive and Vascular Function in the Context of Mental Stress in Young Adults
Study type: INTERVENTIONAL
Overall status: NOT_YET_RECRUITING
Phase: NA
Conditions: Healthy
Keywords: vascular function
flavonoids
cerebral oxygenation
mental stress
cognition
executive function
grape
Flow-mediated dilatation
Functional Near-Infrared Spectroscopy
Lead sponsor: University of Birmingham
Sponsor class: OTHER
Collaborators: name: California Table Grape Commission
First posted: 2025-04-11
Enrollment: 44
Sex: ALL
Minimum age (years): 18
Maximum age (years): 40
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: TREATMENT

Brief summary: The main aim of the current study is to investigate whether consuming grapes rich in flavonoids just before mental stress can protect cerebrovascular and peripheral vascular function, mood and cognition, from the negative effects of mental stress in young healthy adults. A second, exploratory aim, will further address whether quality of habitual diet, microbiome health (composition; metabolites production e.g. Short-chain fatty acids) and levels of cardiorespiratory fitness play a role on the beneficial effects of grapes during mental stress. All participants will receive a high-flavonoid grape intervention (60 g freeze-dried grape powder, equivalent to 300 g fresh grapes) and a low-flavonoid grape intervention (60 g powdere isocaloric-matched control). It is hypothesized that the high-flavonoid grape intervention will improve cortical oxygenation and cognitive function in the context of mental stress, and prevent the stress-induced decline in peripheral endothelial function following stress. Furthermore, it is hypothesized that individuals with poorer diets, cardiorespiratory fitness and a poorer gut microbiome will benefit more from the grape intervention in the context of mental stress.

Detailed description: Psychological stress is widespread in our societies, and has been extensively shown to have negative consequences for human health. Specifically, psychological stress induces significant declines in human vascular function, as measured by brachial Flow-mediated Dilatation (FMD). We have demonstrated that flavonoid interventions can prevent the harmful effects of stress on the vascular system. Indeed, flavonoid-rich interventions have also been extensively shown to improve peripheral and cerebrovascular function in the absence of stress. However, the effect of flavonoids on cerebrovascular function and cognition in the context of mental stress is unknown. In the proposed project, our key objectives are to investigate whether grape intake prior to a mental stress task results in better brain oxygenation and vascular function, which leads to improved cognitive performance and mood in young healthy adults. These data will establish whether grapes can be effective as a 'stress snack' to optimize cognitive and brain function in the context of psychological stress. Furthermore, we will explore whether there are certain participant characteristics that mediate the impact of grape flavonoids on cerebrovascular function and cognition in the context of mental stress. Such as, physical fitness (assessed by a VO2 max test), composition of gut microbiome (assessed by faecal sample), habitual diet (assessed by 3-day food diary and the food frequency questionnaire), and eating behaviour and chronic stress (assessed by the eating behaviour questionnaire and perceived stress scale). This work will be important to guide future dietary recommendations around stress and might ultimately result in increased intake of flavonoid-rich grapes and other flavonoid-rich fruits/vegetables overall.

Eligibility criteria: Inclusion Criteria:

* Males and females
* 18 - 40 years old

Exclusion Criteria:

* Smokers
* Consumes \> 21 units of alcohol per week
* History of cardiovascular, respiratory, metabolic, liver or inflammatory diseases
* Suffers from blood-clotting disorders
* Allergies or intolerances to foods
* On a weight reducing dietary regiment
* Currently taking dietary supplements, including fatty acids and vitamins
* On long-term medication or have been on antibiotics in the last 3 months
* Has an infection at present (e.g. cold) or viral infection

Primary outcomes:
measure: Pre-frontal cortical Tissue Oxygenation Index (NIRS) - TOI
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (during mental stress) and 1 hour 15 minutes post-intervention (during cognitive tasks, 10 minutes post-stress)
measure: Pre-frontal cortical Tissue Oxygenation Index (NIRS) - O2Hb
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (during mental stress) and 1 hour 15 minutes post-intervention (during cognitive tasks, 10 minutes post-stress).
measure: Pre-frontal cortical Tissue Oxygenation Index (NIRS) - HHb
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (during mental stress) and 1 hour 15 minutes post-intervention (during cognitive tasks, 10 minutes post-stress).
measure: Pre-frontal cortical Tissue Oxygenation Index (NIRS) - nTHI
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (during mental stress) and 1 hour 15 minutes post-intervention (during cognitive tasks, 10 minutes post-stress).
Secondary outcomes:
measure: Flow-mediated dilatation (FMD) of the brachial artery
timeFrame: Change from pre-intervention baseline to 2 hours and 2 hours 45 minutes post-intervention (45-90 minutes post-stress).
measure: Common Carotid Artery (CCA) - Blood flow
timeFrame: Change from pre-intervention baseline to 2 hours and 2 hours 45 minutes post-intervention (45-90 minutes post-stress).
measure: Common Carotid Artery (CCA) - Shear rate
timeFrame: Change from pre-intervention baseline to 2 hours and 2 hours 45 minutes post-intervention (45-90 minutes post-stress).
measure: Executive Function (MANT) - Accuracy
timeFrame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress).
measure: Executive Function (Switch) - Accuracy
timeFrame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress).
measure: Executive Function (MANT) - Reaction time
timeFrame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress).
measure: Executive Function (Switch) - Reaction time
timeFrame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress).
measure: Executive Function (MANT) - Inverse Efficiency Score
timeFrame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress).
measure: Executive Function (Switch) - Inverse Efficiency Score
timeFrame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress).
measure: Mood (POMS)
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (immediately following stress), 2 hours and 2 hours 45 minutes post-intervention (45-90 minutes post-stress).
Other outcomes:
measure: Forearm blood flow (FBF)
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (during 8 minutes rest and 8 minutes of mental stress).
measure: Forearm vascular conductance (FVC)
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (during 8 minutes rest and 8 minutes of mental stress).
measure: Cardiovascular activity - Heart rate (HR)
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (during 8 minutes rest and 8 minutes of mental stress).
measure: Cardiovascular activity - R-wave to pulse interval (RPI)
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (during 8 minutes rest and 8 minutes of mental stress).
measure: Cardiovascular activity - Heart rate variability (HRV)
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (during 8 minutes rest and 8 minutes of mental stress).
measure: Cardiovascular activity - beat-to-beat systolic blood pressure (SBP)
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (during 8 minutes rest and 8 minutes of mental stress).
measure: Cardiovascular activity - beat-to-beat diastolic blood pressure (DBP)
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (during 8 minutes rest and 8 minutes of mental stress).
measure: Cardiovascular activity - beat-to-beat mean arterial pressure (MAP)
timeFrame: Change from pre-intervention baseline to 1 hour post-intervention (during 8 minutes rest and 8 minutes of mental stress).
measure: Brachial Systolic Blood Pressure (SBP)
timeFrame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress), 2 hours post-intervention (45 minutes post-stress) and 2 hour 45 minutes post-intervention (90 minutes post-stress).
measure: Brachial Diastolic Blood Pressure (DBP)
timeFrame: Change from pre-intervention baseline to 1 hour 15 minutes post-intervention (10 minutes post-stress), 2 hours post-intervention (45 minutes post-stress) and 2 hour 45 minutes post-intervention (90 minutes post-stress).
Locations:
city: Birmingham
country: United Kingdom
facility: School of Sport, Exercise & Rehabilitation Sciences
Study officials:
References: