Endothelial Dysfunction
Conditions
Keywords
Nitrate, Vitamin C, Endothelial function, Nitric Oxide
Brief summary
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.
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.
Interventions
DIETARY_SUPPLEMENTDietary 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.
DIETARY_SUPPLEMENTNature 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.
DIETARY_SUPPLEMENTPlacebo
Vitamin C matched Placebo capsules that made from starch.
Sponsors
David Travis Thomas
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Investigator)
Intervention model description
Crossover double blinded crossover study
Eligibility
Sex/Gender
ALL
Age
50 Years to 70 Years
Healthy volunteers
Yes
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change of peripheral endothelial function | Change from baseline endothelial function at 4 weeks of each treatment intervention period | Non-invasive technique called peripheral artery tonometry reactive hyperemia (PAT-RH) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change of plasma total nitric oxide (NOx) | Change from baseline plasma NOx at 4 weeks of each treatment intervention period | Sum of nitric oxide metabolites (nitrite and nitrate) were assessed |
| Change of blood biomarker of oxidative stress | Change from baseline oxLDL at 4 weeks of each treatment intervention period | Oxidized low density lipoprotein (oxLDL) |
| Change of blood lipids | Change from baseline blood lipids at 4 weeks of each treatment intervention period | Total cholesterol(TC), low density lipoprotein(LDL), triglycerides(TG), and high density lipoprotein (HDL) |
Countries
United States
Outcome results
None listed