Clinical trial NCT02593305: Dietary Nitrate and Physiological Aging
Official title: Dietary Nitrate Supplementation and Physiological Function in Older Adults
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Aging
Keywords: nitrate
blood flow
blood pressure
vascular function
hypoxia
Lead sponsor: University of Iowa
Sponsor class: OTHER
Collaborators: name: Neogenis Laboratories
First posted: 2015-11-01
Enrollment: 23
Sex: ALL
Minimum age (years): 18
Maximum age (years): 85
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: BASIC_SCIENCE

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.

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.

Eligibility 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.

Primary outcomes:
measure: Change in Carotid Chemosensitivity Following 4 Weeks of Dietary Nitrate Supplementation and Placebo in Older Adults
timeFrame: Pre and post 4 weeks dietary nitrate supplementation and pre and post 4 weeks of placebo.
measure: Change in Systolic Blood Pressure During Metaboreflex Testing Following 4 Weeks of Dietary Nitrate Supplementation and Placebo in Older Adults.
timeFrame: Pre and post 4 weeks dietary nitrate supplementation and pre and post 4 weeks of placebo.
Secondary outcomes:
Other outcomes:
Locations:
city: Iowa City
country: United States
facility: University of Iowa
state: Iowa
Study officials:
affiliation: University of Iowa
name: Darren Casey, PhD.
role: PRINCIPAL_INVESTIGATOR
References: