Caffeine, Cold Exposure, Nitrate
Conditions
Keywords
Cardiovascular Function, Flow mediated dilation
Brief summary
Dietary inorganic nitrate supplementation may have positive implications on cardiovascular function. The aim of this project is to determine if nitrate supplementation can attenuate the effects that caffeine and cold exposure have on the cardiovascular system.
Detailed description
Acute caffeine consumption and cold exposure elicit negative effects on the cardiovascular system. Humans are regularly exposed to such conditions of increased cardiovascular strain, which may lead to elevated chronic cardiovascular risk. On the other hand, dietary inorganic nitrate supplementation is well established to improve cardiovascular function in healthy individuals. Thus, acute nitrate supplementation may compensate for the negative effects that caffeine and the cold place on the cardiovascular system. These effects will be measured using peripheral blood pressure, pulse wave analysis, heart rate variability, forearm blood flow, flow mediated dilation, and blood and saliva markers.
Interventions
DIETARY_SUPPLEMENTTruBeet inorganic beetroot juice
400 mg nitrate-rich beetroot powder, mixed with 300 mL water.
DIETARY_SUPPLEMENTCaffeine
6 mg/kg caffeine powder in capsule form.
OTHERCold pressor test
3 min cold pressor test using the left foot in cold water (0-2 degree).
Sponsors
Biogen Extracts Pvt Ltd
Loughborough University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
PREVENTION
Masking
DOUBLE (Subject, Investigator)
Masking description
Double-blinded using supplement placebos.
Intervention model description
24 participants will complete 4 experimental conditions in a randomized order.
Eligibility
Sex/Gender
ALL
Age
18 Years to 40 Years
Healthy volunteers
Yes
Inclusion criteria
* Blood pressure \< 130 mmHg systolic and \< 85 mmHg diastolic. BMI between 18.5 and 29.9 kg/m2. Females must be naturally menstruating (regular length cycle and menses) or using a form of combined hormonal contraception (for at least 6 months).
Exclusion criteria
* Existing cardiovascular or metabolic conditions. Experience any adverse reactions to experimental procedures or supplements. Allergies to supplements or breakfast items. Involved in any other studies. Blood pressure \> 130 mmHg systolic and \> 85 mmHg diastolic.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Brachial blood pressure | Mean of 5 readings taken pre-supplementation (0 hours) and post-supplementation (2.5 hours). 1 reading was taken pre- cold pressor test (3.5 hours). All measures were recorded on every experimental trial (4 trials with at least 48 h washout between). | Brachial blood pressure was collected using an automatic sphygmomanometer. |
| Flow mediated dilation | Measured pre-supplementation (at 0 hours) and post-supplementation (at 2.5 hours) for every experimental trial (4 trials with at least 48 h washout between). | Baseline diameter, peak diameter, change in diameter, and shear stimulus following flow mediated dilation procedure of the brachial artery with post-occlusion reactive hyperaemia. |
| Central blood pressure and pulse wave variables | Collected pre-supplementation (0 hours), post-supplementation (2.5 hours), and during the cold pressor test (3.5 h) for 4 experimental trials (4 trials with at least 48 hours washout in between). | Mean of 2-3 readings for aortic systolic BP, aortic diastolic BP, HR, Augmentation index, augmentation index corrected to HR of 75 bpm, pulse pressure, and augmentation pressure. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| NIBP continuous blood pressure | Collected pre-supplementation (0 hours), post-supplementation (2.5 hours), and during the cold pressor test (3.5 h) for 4 experimental trials (4 trials with at least 48 hours washout in between). | SBP, DBP, MAP, HR collected continuously for 3-5 min. |
| Heart rate variability | Collected pre-supplementation (0 hours), post-supplementation (2.5 hours), and during the cold pressor test (3.5 h) for 4 experimental trials (4 trials with at least 48 hours washout in between). | Time and frequency domains for heart rate variability collected for 3-5min. |
| Plasma nitrate, nitrite, cGMP | Collected pre-supplementation (0 hours), post-supplementation (2.5 hours), and immediately post- cold pressor test (3.5 h) for 4 experimental trials (4 trials with at least 48 hours washout in between) | Plasma concentrations of nitrate, nitrite, and cGMP. |
| Whole blood RSNO | Collected pre-supplementation (0 hours), post-supplementation (2.5 hours), and immediately post- cold pressor test (3.5 h) for 4 experimental trials (4 trials with at least 48 hours washout in between). | S--nitrosothiols concentration from treated whole blood (NEM, EDTA, potassium ferricyanide). |
| Forearm blood flow | Measured pre-supplementation (at 0 hours) and post-supplementation (at 2.5 hours) for every experimental trial (4 trials with at least 48 h washout between). | Forearm blood flow pre- and post-PORH (post occlusion reactive hyperaemia) via strain gauge plethysmography. |
| Salivary nitrate and nitrite | Measured pre-supplementation (at 0 hours) and post-supplementation (at 2.5 hours) for every experimental trial (4 trials with at least 48 h washout between). | Salivary concentration of nitrate and nitrite |
Countries
United Kingdom
Outcome results
None listed