Role of Flavanols in Exercise and Aging

Acute and Long-term Effects of Dietary Flavanols on Local Control of Skeletal Muscle Blood Flow During Exercise in Young and Old Humans

It has well known that diets rich in fruits, vegetables and cocoa products are associated with positive health benefits and these positive effects have been shown to be due to compounds they contain called flavanols. Flavanols have been shown to exert their positive effects by indirectly increasing nitric oxide (NO) bioavailability. NO is a potent vasodilator that is believed to play a role in increasing blood flow to active muscle during exercise. This regulatory process is impaired with healthy aging. The underlying premise to this study is that if NO bioavailability can be increased following flavanol ingestion, will there be a restoration of blood flow during exercise in older individuals? Accordingly, the first part of this research project will compare the acute vascular effects of flavanol ingestion between a young and old group. The investigators have hypothesized that both groups will show an improvement in blood flow to active muscle during exercise, though the magnitude of the change will be greater in the older group. The second part of this project will look at the effects of 4 weeks of daily flavanol ingestion in the old group. The investigators hypothesize that subjects will demonstrate an improvement in blood flow to active muscle during exercise after the 4 week intervention and that the magnitude of the change will be greater than the acute effects. Findings from this proposal will provide evidence for the efficacy of flavanols to be used (as a simple and safe lifestyle intervention) to reverse or combat impaired blood flow regulation in older individuals.

Study Overview

• Status: Completed
• Conditions: Aging
• Intervention / Treatment: Dietary supplement: High Flavanol Trial; Dietary supplement: Low Flavanol Trial; Dietary supplement: High Flavanol Trial; long-term; Dietary supplement: Low Flavanol Trial; long-term effects

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Texas
    • Austin, Texas, United States, 78712
      • University of Texas at Austin: Environmental and Autonomic Physiology Laboratory

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 80 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Males and Females between 18 - 30 years old
• Males and Females between 60 - 80 years old

Exclusion Criteria:

• cardiovascular and/or microvascular disease
• blood clotting disorder
• pregnant lady
• current smoker (or regularly smoked within last year)
• a history of an adverse reaction to cold
• taking medications known to effect the autonomic nervous system

Study Plan

How is the study designed?

Design Details

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

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Acute effects of flavanol consumption; The outcome measurements will be made on all study participants before and 2 hours after consumption of the high flavanol beverage.	Dietary supplement: High Flavanol Trial; The experimental trial (high flavanol content) will involve the consumption of a beverage containing about 1000mg of cocoa flavanols.
Placebo Comparator: Low Flavanol Trial; acute effects; Once again, the outcome measurements will be made on all study participants before and 2 hours after consumption of the low flavanol beverage.	Dietary supplement: Low Flavanol Trial; The placebo trial (low flavanol content) will involve the consumption of a beverage containing 75 mg of cocoa flavanols.
Experimental: Long-term effects of flavanol consumption; Only those study participants over 60 years of age will continue with this arm of the trial. The same outcome measures will be performed following 4 weeks of daily consumption of a high flavanol beverage.	Dietary supplement: High Flavanol Trial; long-term; The experimental trial (high flavanol content) will involve the daily consumption of a beverage containing about 1000mg of cocoa flavanols for 4 weeks. Subjects will be provided with 28 packets of the beverage to take home with them.
Placebo Comparator: Low Flavanol Trial; long-term effects; Only those study participants over 60 years of age will continue with this arm of the trial. The same outcome measures will be performed following 4 weeks of daily consumption of a low flavanol beverage.	Dietary supplement: Low Flavanol Trial; long-term effects; The placebo trial (low flavanol content) will involve the daily consumption of a beverage containing 75 mg of cocoa flavanols for 4 weeks. Subjects will be provided with 28 packets to take home with them.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in femoral blood flow during exercise following flavanol consumption	Blood flow regulation to active muscles during knee extension exercise can be assessed by using ultrasound to measure blood flow in the femoral artery. This will be done before and after stimulation of the sympathetic nervous system. A baseline value will be obtained and then the measurement will be performed again 2 hours after flavanol ingestion.	During knee extension exercise, change from baseline in blood flow 2 hours post flavanol ingestion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in flow-mediated dilation (FMD) following flavanol consumption	Flow-mediated dilation is commonly used as an index of nitric oxide bioavailability. Nitric oxide is believed to play a role in blood flow regulation during exercise. A baseline value will be obtained and then the measurement will be performed again 2 hours after flavanol ingestion.	Change from baseline in FMD 2 hours post flavanol ingestion

Collaborators and Investigators

• Sponsor: University of Texas at Austin
• Investigators: Principal Investigator: Michelle Harrison, M.A., University of Texas at Austin

Study record dates

Study Major Dates

• Study Start: December 1, 2012
• Primary Completion (Actual): April 1, 2014
• Study Completion (Actual): April 1, 2014

Study Registration Dates

• First Submitted: March 8, 2012
• First Submitted That Met QC Criteria: March 15, 2012
• First Posted (Estimate): March 19, 2012

Study Record Updates

• Last Update Posted (Estimate): June 25, 2014
• Last Update Submitted That Met QC Criteria: June 24, 2014
• Last Verified: May 1, 2014

More Information

Terms related to this study

• Keywords: Exercise; Aging; Antioxidant; Nitric Oxide; Blood Flow; Flavanol; Young (18-30 yrs); Aging (60 - 80 yrs)
• Other Study ID Numbers: 2012-02-0114