A Phase 2 interventional study of Beetroot juice and Beetroot juice placebo in Peripheral Arterial Disease, sponsored by David N. Proctor, PhD. Completed at 1 site in United States. Open to participants aged 21 Years to 85 Years. Per ClinicalTrials.gov, last updated 2026-08-13.
Sponsored by David N. Proctor, PhD · Phase 2, Interventional, and Treatment
In this study the investigators will test the hypothesis that short-term consumption of inorganic nitrate (supplied in concentrated beetroot juice) enhances coronary blood flow responses, large artery hemodynamics, and leg oxygenation/exercise tolerance in patients with peripheral arterial disease (PAD). Understanding and improving blood flow regulation in the heart and skeletal muscles of patients with PAD is important because exercise triggers symptoms of leg pain and substantially raises blood pressure and myocardial demand in these patients.
Peripheral arterial disease (PAD) is a strong predictor of cardiovascular mortality and negatively affects functional capacity and quality of life for as many as 14 million patients in the U.S. alone. One open-label study showed that acute consumption of beetroot juice improved 6 min walk performance, reduced blood pressure, and enhanced leg muscle oxygenation in PAD patients. However, no studies have rigorously confirmed these findings in a double-blind manner, nor have the effects of this supplement been investigated (acutely or short-term) in the coronary circulation of PAD patients.
In addition to studying its effects on graded treadmill walking performance and consequent large artery vasodilation, the present study will examine the effects of short-term beetroot juice consumption (twice/day) on both coronary and leg vasodilator (graded calf flexion) and vasoconstrictor (isometric handgrip, voluntary apnea) responses in patients with PAD. Participants will randomly consume either nitrate-rich or nitrate-depleted beetroot juice with a 7 to 14 day wash-out period between. Effects of beetroot juice consumption on plasma nitrate, nitrite and methemoglobin will also be assessed.
1,542 studies on the registry are indexed under Peripheral Arterial Disease; 282 are open to participants now.
This study's enrollment of 11 is below the median of 74 across 1,066 interventional studies indexed under Peripheral Arterial Disease.
Browse Peripheral Arterial Disease studies →David N. Proctor, PhD is the lead sponsor of 2 studies on the registry; none are open to participants now.
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Exclusion Criteria:
Subjects will consume 70 ml of beetroot juice (Beet-It Organic Shot) twice per day (morning, afternoon) for 5 to 7 days to assess the short term effects of this nitrate supplement on graded treadmill walking responses (day 4) and vasodilator/vasoconstrictor responses in the coronary and lower leg circulations (day 5 or 6 or 7). On both study visits, subjects will consume their morning dose 1 hour 45 min before experiments begin.
Drug: Beetroot juice
Subjects will consume 70 ml of beetroot juice (Beet-It Organic Placebo) twice per day (morning, afternoon) for 5 to 7 days to assess the short term effects of this nitrate supplement on graded treadmill walking responses (day 4) and vasodilator/vasoconstrictor responses in the coronary and lower leg circulations (day 5 or 6 or 7). On both study visits, subjects will consume their morning dose 1 hour 45 min before experiments begin.
Drug: Beetroot juice placebo
This beverage contains 0.3 g of inorganic nitrate per 70 ml container, and is bottled and supplied by James White Drinks (UK).
Also known as: Beet-It Organic Shot
This beverage is identical in look and taste to the Beet-It organic shot, but has the nitrate removed. It is also bottled and supplied by James White Drinks (UK).
Also known as: Beet-It organic placebo
Peak Treadmill Time
Peak treadmill time was determined using the Gardner treadmill protocol, measured as the number of seconds the participant was able to walk until they asked to stop the test due to leg fatigue.
Time frame: 4 to 6 days after initiating daily ingestion of beetroot juice
Coronary Flow Velocity Response to Peak Plantar Flexion Exercise
Change in LAD coronary artery flow velocity, measured using transthoracic ultrasound, from baseline rest to peak plantar flexion exercise. Single leg plantar flexion exercise of the most symptomatic leg was performed at a rate of 20 contractions per minute, with increases in workload (1 kg) every minute until volitional fatigue, or until maximum exercise duration of 14 min was reached.
Time frame: 4 days after initiating daily ingestion of beetroot juice
Resting Blood Pressure
Resting mean arterial blood pressure (mmHg) obtained prior to the exercise treadmill test obtained using an automated arm blood pressure cuff.
Time frame: 4 to 6 days after initiating daily ingestion of beetroot juice
Plasma Nitrate Concentration Prior to Plantar Flexion Test Visit.
Venous blood samples were collected via venipuncture for storage and later determination of plasma nitrate concentration at Wake Forest University.
Time frame: 4 to 6 days after initiating ingestion of beetroot juice
| Milestone | Beetroot Juice First, Then Placebo | Placebo First, Then Beetroot Juice |
|---|---|---|
| Started | 6 | 5 |
| Completed | 6 | 5 |
| Not completed | 0 | 0 |
| Milestone | Beetroot Juice First, Then Placebo | Placebo First, Then Beetroot Juice |
|---|---|---|
| Started | 6 | 5 |
| Completed | 6 | 5 |
| Not completed | 0 | 0 |
| Milestone | Beetroot Juice First, Then Placebo | Placebo First, Then Beetroot Juice |
|---|---|---|
| Started | 6 | 5 |
| Completed | 6 | 5 |
| Not completed | 0 | 0 |
Peak treadmill time was determined using the Gardner treadmill protocol, measured as the number of seconds the participant was able to walk until they asked to stop the test due to leg fatigue.
| s | Beetroot Juice (Beet-It Organic Shot) | Beetroot Juice Placebo (Beet-It Organic Placebo) |
|---|---|---|
| Peak Treadmill Time | 730.5 ± 604.5 | 691.3 ± 547.7 |
Change in LAD coronary artery flow velocity, measured using transthoracic ultrasound, from baseline rest to peak plantar flexion exercise. Single leg plantar flexion exercise of the most symptomatic leg was performed at a rate of 20 contractions per minute, with increases in workload (1 kg) every minute until volitional fatigue, or until maximum exercise duration of 14 min was reached.
| cm/s | Beetroot Juice (Beet-It Organic Shot) | Beetroot Juice Placebo (Beet-It Organic Placebo) |
|---|---|---|
| Coronary Flow Velocity Response to Peak Plantar Flexion Exercise | 11.83 ± 10.46 | 7.06 ± 6.01 |
Resting mean arterial blood pressure (mmHg) obtained prior to the exercise treadmill test obtained using an automated arm blood pressure cuff.
| mmHg | Beetroot Juice (Beet-It Organic Shot) | Beetroot Juice Placebo (Beet-It Organic Placebo) |
|---|---|---|
| Resting Blood Pressure | 85 ± 8 | 91 ± 9 |
Venous blood samples were collected via venipuncture for storage and later determination of plasma nitrate concentration at Wake Forest University.
| uM | Beetroot Juice (Beet-It Organic Shot) | Beetroot Juice Placebo (Beet-It Organic Placebo) |
|---|---|---|
| Plasma Nitrate Concentration Prior to Plantar Flexion Test Visit. | 763.50 ± 123.22 | 46.28 ± 28.18 |
Collected over From enrollment through study completion, approximately 4-6 weeks per participant.. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Beet-It Organic Shot | 0/11 (0%) | 0/11 (0%) | 0/11 (0%) |
| Beetroot Juice Placebo (Beet-It Organic Placebo) | 0/11 (0%) | 0/11 (0%) | 0/11 (0%) |
All randomized study participants (Sequence 1: Beetroot Juice then Placebo; Sequence 2: Placebo then Beetroot Juice).
| Age, Categorical(Participants) | All Study Participants |
|---|---|
| <=18 years | 0 |
| Between 18 and 65 years | 6 |
| >=65 years | 5 |
| Age, Continuous(years) | All Study Participants |
|---|---|
| Mean | 64.5 ± 8 |
| Sex: Female, Male(Participants) | All Study Participants |
|---|---|
| Female | 2 |
| Male | 9 |
| Ethnicity (NIH/OMB)(Participants) | All Study Participants |
|---|---|
| Hispanic or Latino | 0 |
| Not Hispanic or Latino | 11 |
| Unknown or Not Reported | 0 |
| Region of Enrollment(participants) | All Study Participants |
|---|---|
| United States | 11 |
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David N. Proctor, PhD