Dietary Nitrate and Physiological Aging

Dietary Nitrate Supplementation and Physiological Function in Older Adults

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.

Study Overview

• Status: Completed
• Conditions: Aging
• Intervention / Treatment: Dietary supplement: Super Beets; Dietary supplement: Super Beets Placebo

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.

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

Contacts and Locations

Study Locations

• United States
  • Iowa
    • Iowa City, Iowa, United States, 52242
      • University of Iowa

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

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.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

3

Arms and Interventions

Participant Group / 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 Names: Beetroot crystals; Dietary supplement: Super Beets Placebo; Nitrate deficient beetroot powder (10g/day) for 4 weeks; Other Names: 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 Names: Beetroot crystals; Dietary supplement: Super Beets Placebo; Nitrate deficient beetroot powder (10g/day) for 4 weeks; Other Names: Beetroot crystals no nitrate
No Intervention: Young Comparison; Young control group, used for age-related comparisons. This group did not go through any intervention.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Carotid Chemosensitivity Following 4 Weeks of Dietary Nitrate Supplementation and Placebo in Older Adults	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.	Pre and post 4 weeks dietary nitrate supplementation and pre and post 4 weeks of placebo.
Change in Systolic Blood Pressure During Metaboreflex Testing Following 4 Weeks of Dietary Nitrate Supplementation and Placebo in Older Adults.	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.	Pre and post 4 weeks dietary nitrate supplementation and pre and post 4 weeks of placebo.

Collaborators and Investigators

• Sponsor: Darren P Casey
• Collaborators: Neogenis Laboratories
• Investigators: Principal Investigator: Darren Casey, PhD., University of Iowa

Study record dates

Study Major Dates

• Study Start: October 1, 2015
• Primary Completion (Actual): April 28, 2017
• Study Completion (Actual): April 28, 2017

Study Registration Dates

• First Submitted: October 27, 2015
• First Submitted That Met QC Criteria: October 29, 2015
• First Posted (Estimate): November 1, 2015

Study Record Updates

• Last Update Posted (Actual): October 14, 2019
• Last Update Submitted That Met QC Criteria: September 24, 2019
• Last Verified: September 1, 2019

More Information

Terms related to this study

• Keywords: blood pressure; vascular function; hypoxia; blood flow; nitrate
• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Adrenergic Agents; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Autonomic Agents; Peripheral Nervous System Agents; Neurotransmitter Uptake Inhibitors; Membrane Transport Modulators; Dopamine Agents; Dopamine Uptake Inhibitors; Central Nervous System Stimulants; Sympathomimetics; Adrenergic Uptake Inhibitors; Methamphetamine
• Other Study ID Numbers: 201507735

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