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

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

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.

Study Overview

• Status: Completed
• Conditions: Caffeine; Nitrate; Cold Exposure
• Intervention / Treatment: Dietary supplement: TruBeet inorganic beetroot juice; Dietary supplement: Caffeine; Other: Cold pressor test

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.

• Study Type: Interventional
• Enrollment (Actual): 24
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Loughborough, United Kingdom, LE11 3TU
    • Loughborough University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Nitrate, caffeine, and cold pressor test (CPT); All outcome variables will be measured for 24 participants in a trial where they receive 400 mg nitrate in the form of beetroot extract, 6 mg/kg caffeine powder, and undergo a 3 min cold pressor test.	Dietary supplement: TruBeet inorganic beetroot juice; 400 mg nitrate-rich beetroot powder, mixed with 300 mL water.; Dietary supplement: Caffeine; 6 mg/kg caffeine powder in capsule form.; Other: Cold pressor test; 3 min cold pressor test using the left foot in cold water (0-2 degree).
Placebo Comparator: Nitrate, placebo caffeine, and CPT; All outcome variables will be measured for 24 participants in a trial where they receive 400 mg nitrate in the form of beetroot extract, 6 mg/kg cornflour (caffeine placebo), and undergo a 3 min cold pressor test.	Dietary supplement: TruBeet inorganic beetroot juice; 400 mg nitrate-rich beetroot powder, mixed with 300 mL water.; Other: Cold pressor test; 3 min cold pressor test using the left foot in cold water (0-2 degree).
Placebo Comparator: Placebo nitrate, caffeine, and CPT; All outcome variables will be measured for 24 participants in a trial where they receive nitrate-depleted beetroot extract (placebo), 6 mg/kg caffeine powder, and undergo a 3 min cold pressor test.	Dietary supplement: Caffeine; 6 mg/kg caffeine powder in capsule form.; Other: Cold pressor test; 3 min cold pressor test using the left foot in cold water (0-2 degree).
Placebo Comparator: Placebo nitrate, placebo caffeine, and CPT; All outcome variables will be measured for 24 participants in a trial where they receive nitrate-depleted beetroot extract (placebo), 6 mg/kg cornflour (caffeine placebo), and undergo a 3 min cold pressor test.	Other: Cold pressor test; 3 min cold pressor test using the left foot in cold water (0-2 degree).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Brachial blood pressure	Brachial blood pressure was collected using an automatic sphygmomanometer.	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).
Flow mediated dilation	Baseline diameter, peak diameter, change in diameter, and shear stimulus following flow mediated dilation procedure of the brachial artery with post-occlusion reactive hyperaemia.	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).
Central blood pressure and pulse wave variables	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.	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).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Forearm blood flow	Forearm blood flow pre- and post-PORH (post occlusion reactive hyperaemia) via strain gauge plethysmography.	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 nitrate and nitrite	Salivary concentration of 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).
Heart rate variability	Time and frequency domains for heart rate variability collected for 3-5min.	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).
NIBP continuous blood pressure	SBP, DBP, MAP, HR collected continuously for 3-5 min.	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).
Whole blood RSNO	S--nitrosothiols concentration from treated whole blood (NEM, EDTA, potassium ferricyanide).	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 nitrate, nitrite, cGMP	Plasma concentrations of nitrate, nitrite, and 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)

Collaborators and Investigators

• Sponsor: Loughborough University
• Collaborators: Biogen Extracts Pvt Ltd
• Investigators: Principal Investigator: Stephen Bailey, Loughborough University

Study record dates

Study Major Dates

• Study Start (Actual): December 5, 2023
• Primary Completion (Actual): November 1, 2024
• Study Completion (Actual): April 1, 2025

Study Registration Dates

• First Submitted: September 12, 2024
• First Submitted That Met QC Criteria: September 17, 2024
• First Posted (Actual): September 19, 2024

Study Record Updates

• Last Update Posted (Estimated): September 12, 2025
• Last Update Submitted That Met QC Criteria: September 5, 2025
• Last Verified: August 1, 2024

More Information

Terms related to this study

• Keywords: Cardiovascular Function; Flow mediated dilation
• Additional Relevant MeSH Terms: Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Alkaloids; Purinones; Purines; Xanthines; Caffeine
• Other Study ID Numbers: LoughboroughUAM

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No