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Completed

NCT Number: NCT06602921

The Effects of Nitrate, Caffeine, and Cold Exposure on Cardiovascular Function.

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.

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Key information

Conditions

Nitrate Caffeine Cold Exposure

Age range

18 year–40 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Loughborough University

Loughborough, LE11 3TU, United Kingdom

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

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

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.

Treatment and study plan

TruBeet inorganic beetroot juice

Dietary Supplement

400 mg nitrate-rich beetroot powder, mixed with 300 mL water.

Caffeine

Dietary Supplement

6 mg/kg caffeine powder in capsule form.

Cold pressor test

Other

3 min cold pressor test using the left foot in cold water (0-2 degree).

Primary outcomes

  1. Brachial blood pressure

    Time frame: 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.

  2. Flow mediated dilation

    Time frame: 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.

  3. Central blood pressure and pulse wave variables

    Time frame: 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 outcomes

  1. Forearm blood flow

    Time frame: 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.

  2. Salivary nitrate and nitrite

    Time frame: 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

  3. Heart rate variability

    Time frame: 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.

  4. NIBP continuous blood pressure

    Time frame: 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.

  5. Whole blood RSNO

    Time frame: 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).

  6. Plasma nitrate, nitrite, cGMP

    Time frame: 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.

Sponsors and collaborators

Lead sponsor

Loughborough University

Other

Collaborators

  • Biogen Extracts Pvt Ltd

Registry information

Official study title

Does Dietary Nitrate Supplementation Attenuate the Cardiovascular Strain Elicited by Caffeine and Cold Exposure in Healthy Individuals?

Important dates

Study start
2023
Primary completion
2024
Study completion
2025
First posted
Sep 19, 2024
Registry last updated
Sep 12, 2025

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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