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Dietary Nitrate and Physiological Aging

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ClinicalTrials.gov Identifier: NCT02593305
Recruitment Status : Completed
First Posted : November 2, 2015
Results First Posted : October 14, 2019
Last Update Posted : October 14, 2019
Sponsor:
Collaborator:
Neogenis Laboratories
Information provided by (Responsible Party):
Darren P Casey, University of Iowa

Brief Summary:
The main purpose/s of this study is to examine the effects of 4 weeks of dietary nitrate supplementation on peripheral chemoreceptor sensitivity, spontaneous baroreflex sensitivity, and blood pressure responsiveness to a variety of physiological stressors in older healthy adults. We will also examine the effect of dietary nitrate supplementation on measures of central artery stiffness and aortic blood pressure in older adults. Lastly, we will also recruit a group of young subjects in order to help characterize the age-related changes associated with the physiological outcome measures of the present study.

Condition or disease Intervention/treatment Phase
Aging Dietary Supplement: Super Beets Dietary Supplement: Super Beets Placebo Not Applicable

Detailed Description:
1 in 3 adults in the U.S. have hypertension which is known to increase the risk of heart disease and stroke. Blood pressure regulation is mediated by many factors including but not limited to metabolic factors, pressure/stretch sensing receptors located in the aorta and carotid arteries, endothelial cell function, and kidney function (via water and sodium absorption/excretion). It has been shown that many of these regulatory mechanisms are altered and/or become dysfunctional with aging. Specifically older adults commonly demonstrate a decreased sensitivity in pressure receptors and/or endothelial dysfunction. Additionally with aging, there is an increase in sympathetic nervous system activity and arterial stiffness which can contribute to higher blood pressure. The important vasodilator, nitric oxide (NO), has been implicated as a key signaling molecule involved in several of the mechanisms in blood pressure regulation outlined above. A decreased NO production or bioavailability is thought to contribute to several of the physiologic changes that come with aging. Therefore, the overall aim of this study is to use a randomized, double-blind crossover, placebo controlled study to examine the effects of acute dietary nitrate supplementation (to boost bioavailable NO) on various parameters of blood pressure regulation and responsiveness in normal healthy older adults. Our main hypothesis is that 4 weeks of dietary nitrate supplementation will decrease the blood pressure responses in older adults in response to a variety of physiological stressors.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 23 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary Purpose: Basic Science
Official Title: Dietary Nitrate Supplementation and Physiological Function in Older Adults
Study Start Date : October 2015
Actual Primary Completion Date : April 28, 2017
Actual Study Completion Date : April 28, 2017

Arm Intervention/treatment
Experimental: Beetroot crystals (nitrate), then placebo
Participants will receive a nitrate rich beetroot powder (10g/day) for 4 weeks. After a washout period of 4 weeks, they will then receive the placebo (beetroot powder, no nitrate) for 4 weeks.
Dietary Supplement: Super Beets
Nitrate rich beetroot powder (10g/day) for 4 weeks
Other Name: Beetroot crystals

Dietary Supplement: Super Beets Placebo
Nitrate deficient beetroot powder (10g/day) for 4 weeks
Other Name: Beetroot crystals no nitrate

Experimental: Placebo, then beetroot crystals (nitrate)
Participants will receive a beetroot powder placebo (no nitrate) for 4 weeks. After a 4 week washout period, they will receive the nitrate rich beetroot powder for 4 weeks.
Dietary Supplement: Super Beets
Nitrate rich beetroot powder (10g/day) for 4 weeks
Other Name: Beetroot crystals

Dietary Supplement: Super Beets Placebo
Nitrate deficient beetroot powder (10g/day) for 4 weeks
Other Name: Beetroot crystals no nitrate

No Intervention: Young Comparison
Young control group, used for age-related comparisons. This group did not go through any intervention.



Primary Outcome Measures :
  1. Change in Carotid Chemosensitivity Following 4 Weeks of Dietary Nitrate Supplementation and Placebo in Older Adults [ Time Frame: Pre and post 4 weeks dietary nitrate supplementation and pre and post 4 weeks of placebo. ]
    Carotid chemosensitivity examined by measuring hypoxia ventilatory responsiveness in older adults before and after 4 weeks of beet root juice supplementation and placebo. Chemoreflex sensitivity was quantified as the change in ventilation in relation to the change in pulse oxygen saturation.

  2. Change in Systolic Blood Pressure During Metaboreflex Testing Following 4 Weeks of Dietary Nitrate Supplementation and Placebo in Older Adults. [ Time Frame: Pre and post 4 weeks dietary nitrate supplementation and pre and post 4 weeks of placebo. ]
    Muscle metaboreflex examined by measuring systolic blood pressure responses to ischemic isometric muscle contraction in older adults before and after 4 weeks of beet root juice supplementation and placebo.



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Ages Eligible for Study:   18 Years to 85 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Two separate age groups were included.

Inclusion Criteria:

  • Healthy young adults 18-35 years of age (comparison group)
  • Healthy older adults 60-85 years of age (intervention group)

Exclusion Criteria:

  • Hypertension, hyperlipidemia, current smoker or smoker within the last year, heart disease, diabetes, Chronic obstructive pulmonary disease, asthma, sleep apnea, Raynaud's disease, body mass index (BMI) > 30 kg/m2, allergy medication, clinical depression, autonomic disorders and other conditions or medications that might normally alter cardiovascular function, exercise tolerance, and/or blood pressure responses.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02593305


Locations
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United States, Iowa
University of Iowa
Iowa City, Iowa, United States, 52242
Sponsors and Collaborators
Darren P Casey
Neogenis Laboratories
Investigators
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Principal Investigator: Darren Casey, PhD. University of Iowa
  Study Documents (Full-Text)

Documents provided by Darren P Casey, University of Iowa:
Informed Consent Form  [PDF] July 28, 2016


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Responsible Party: Darren P Casey, Assistant Professor, University of Iowa
ClinicalTrials.gov Identifier: NCT02593305     History of Changes
Other Study ID Numbers: 201507735
First Posted: November 2, 2015    Key Record Dates
Results First Posted: October 14, 2019
Last Update Posted: October 14, 2019
Last Verified: September 2019
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Keywords provided by Darren P Casey, University of Iowa:
nitrate
blood flow
blood pressure
vascular function
hypoxia
Additional relevant MeSH terms:
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Methamphetamine
Central Nervous System Stimulants
Physiological Effects of Drugs
Sympathomimetics
Autonomic Agents
Peripheral Nervous System Agents
Dopamine Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Adrenergic Agents
Adrenergic Uptake Inhibitors
Neurotransmitter Uptake Inhibitors
Membrane Transport Modulators
Dopamine Uptake Inhibitors