Nitrate and Vitamin C on Vascular Health Oxidative Stress

The Combined Effect of Dietary Nitrate and Vitamin C on Endothelial Function, Oxidative Stress Biomarkers, and Blood Lipids

The objective of this study is to examine whether the co-administration of dietary nitrate combined with vitamin C for 4 weeks in patients at risk for CVD would yield robust effects on endothelial function using blood measures and a non-invasive technique (Peripheral Artery Tonometry) compared to dietary nitrate supplementation alone.

Study Overview

• Status: Completed
• Conditions: Endothelial Dysfunction
• Intervention / Treatment: Dietary supplement: Dietary nitrate in the form of beetroot juice for all participnats; Dietary supplement: Nature Made vitamin c 1000 mg; Dietary supplement: Placebo

Detailed Description

This is a 10 week randomized, cross-over, double-blinded, placebo-controlled study. This study was designed to compare the magnitude changes in RHI (primary outcome), plasma NO metabolites (nitrate and nitrite), and plasma vitamin C, plasma oxidized LDL, and blood (secondary outcome) following treatment with inorganic nitrate and vitamin C placebo (N) and inorganic nitrate combined with vitamin C (NC). Following baseline testing, eligible subjects were randomized to receive either treatment (N) or treatment (NC) for 4 weeks (period1), and participants were then crossed over to the alternate treatment for another 4 weeks (period 2). There was a 2-week washout at crossover.

• Study Type: Interventional
• Enrollment (Actual): 23
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Kentucky
    • Lexington, Kentucky, United States, 40536
      • University of Kentucky
    • Lexington, Kentucky, United States, 40514
      • University of Kentucky

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 50 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Age: between 50 and 70 years
• Body mass index (BMI) of 18.5-34.9 kg/m2
• Reactive hyperemia index (RHI) of < or equal to 2
• High cholesterol levels with LDL concentrations (>130 mg/dL)
• Not receiving any lipid lowering therapy.
• Non-smokers

Exclusion Criteria:

• Evidence of overt atherosclerotic disease (i.e., documented medical history of coronary artery disease, peripheral artery disease, cardiovascular disease, and stroke).
• Any surgery or medical history that could confound study results, such as a history of bowel resection, rheumatoid arthritis, inflammatory bowel disease, celiac disease, diabetes, uncontrolled hypertension (systolic blood pressure >160 mm Hg or diastolic blood pressure >100 mm Hg), controlled hypertension on clonidine medication.
• Participants were ineligible if they had been diagnosed with the following medical conditions such as active cancer, severe anemia (Hb < 10mg/dL), hepatic or renal disease, heart failure, or finger deformities.
• HIV-positive patients on combination antiretroviral therapy because of potential pharmacokinetic interactions with beetroot juice were excluded.
• Participants were also excluded if they reported taking any form of hormone replacement therapy (estrogens, progesterone, and testosterone), multivitamin supplements that provides >100% of RDA, or any of the following medications that attenuate nitrate conversion to NO: proton pump inhibitors (PPI) and antibiotics.
• Participants who consumed greater than 6 drinks of alcohol (any form) per week, performed structured resistance or aerobic training for more than 1-hour four times per week, or participated in other clinical intervention within the previous 30 days were excluded from the study.
• Eligible subjects were asked to avoid using the mouthwash before and throughout the study duration. In addition, enrolled participants were advised to consume low- vitamin c diet throughout the study. They were provided at the beginning of the study with a list of high vitamin C foods/fortified foods to avoid during the study.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Randomization and Dietary supplement Interventions; The dietary nitrate supplement was provided in the form of commercial beetroot juice (Sport Beet IT shot, Heartbeet Ltd) for all participants, whereas vitamin C and the placebo were provided as supplement capsules. Participants were asked to consume one dose/shot of sport Beet IT (70ml) that delivers on average 300-400mg of inorganic nitrate every day in the morning during the four-week study period, except for the test days and washout weeks. Accordingly, the participant were asked to consume the concentrated beetroot juice with breakfast meals, and then the vitamin C supplement (1000 mg)or placebo at the same time one-hour post beetroot juice supplementation	Dietary supplement: Dietary nitrate in the form of beetroot juice for all participnats; participants asked to consume dietary nitrate in the form of beet juice everyday in the morning and then one hour later, the vitamin C capsules.; Other Names: Sport Beet IT shot; Dietary supplement: Nature Made vitamin c 1000 mg; vitamin C and the placebo were provided as supplement capsules. Participants were asked to consume one dose/shot of sport Beet IT (70ml) that delivers on average 300-400mg of inorganic nitrate every day in the morning during the four-week study period, except for the test days and washout weeks. Accordingly, the participant were asked to consume the daily vitamin C supplement (1000 mg) or placebo one-hour post beetroot juice supplementation.
Placebo Comparator: Placebo; Vitamin C placebo was matched with the active vitamin c capsules in shape, color, and size.	Dietary supplement: Dietary nitrate in the form of beetroot juice for all participnats; participants asked to consume dietary nitrate in the form of beet juice everyday in the morning and then one hour later, the vitamin C capsules.; Other Names: Sport Beet IT shot; Dietary supplement: Placebo; Vitamin C matched Placebo capsules that made from starch.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change of peripheral endothelial function	Non-invasive technique called peripheral artery tonometry reactive hyperemia (PAT-RH)	Change from baseline endothelial function at 4 weeks of each treatment intervention period

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change of plasma total nitric oxide (NOx)	Sum of nitric oxide metabolites (nitrite and nitrate) were assessed	Change from baseline plasma NOx at 4 weeks of each treatment intervention period
Change of blood biomarker of oxidative stress	Oxidized low density lipoprotein (oxLDL)	Change from baseline oxLDL at 4 weeks of each treatment intervention period
Change of blood lipids	Total cholesterol(TC), low density lipoprotein(LDL), triglycerides(TG), and high density lipoprotein (HDL)	Change from baseline blood lipids at 4 weeks of each treatment intervention period

Collaborators and Investigators

• Sponsor: David Travis Thomas

Publications and helpful links

General Publications

• Basaqr R, Skleres M, Jayswal R, Thomas DT. The effect of dietary nitrate and vitamin C on endothelial function, oxidative stress and blood lipids in untreated hypercholesterolemic subjects: A randomized double-blind crossover study. Clin Nutr. 2021 Apr;40(4):1851-1860. doi: 10.1016/j.clnu.2020.10.012. Epub 2020 Oct 14.

Study record dates

Study Major Dates

• Study Start (Actual): February 5, 2018
• Primary Completion (Actual): September 15, 2019
• Study Completion (Actual): December 13, 2019

Study Registration Dates

• First Submitted: February 14, 2020
• First Submitted That Met QC Criteria: February 21, 2020
• First Posted (Actual): February 25, 2020

Study Record Updates

• Last Update Posted (Actual): February 25, 2020
• Last Update Submitted That Met QC Criteria: February 21, 2020
• Last Verified: February 1, 2020

More Information

Terms related to this study

• Keywords: Endothelial function; Vitamin C; Nitric Oxide; Nitrate
• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Protective Agents; Micronutrients; Vitamins; Antioxidants; Ascorbic Acid
• Other Study ID Numbers: 17-0412-F3R

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