Age-associated Arterial Dysfunction, Western Diet, and Aerobic Exercise: Role of the Gut Microbiome



Status:Recruiting
Conditions:Healthy Studies
Therapuetic Areas:Other
Healthy:No
Age Range:18 - 79
Updated:4/17/2018
Start Date:March 15, 2018
End Date:June 1, 2021
Contact:Kara Lubieniecki, MS
Email:ipalab@colorado.edu
Phone:303-735-6410

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The risk of developing cardiovascular diseases increases with aging largely due to
age-related declines in the function of arteries (arterial dysfunction), which are influenced
by common lifestyle factors such as consumption of a "Western" diet and lack of sufficient
physical activity; thus, it is important to study how these factors interact to affect artery
function. This study will determine whether changes to the gut microbiome (the collection of
bacteria and other "microbes" living in the intestinal tract) with aging, Western diet
consumption and aerobic exercise influence arterial function, and the biological pathways
(mechanisms) involved. Specifically, the investigators will perform a randomized,
single-blind, controlled feeding crossover study design (comparing Western diet to
non-Western diet consumption) in young and older, exercising and non-exercising healthy
adults to determine the time course effects (temporal association) of diet on the gut
microbiome and arterial function. Overall, this research has potential to establish the gut
microbiome as a possible target for treating/preventing age-related arterial dysfunction and
reducing the risk of age-associated cardiovascular diseases.

In order to investigate how age-related changes to the gut microbiome, as modulated by
Western diet and exercise, influences arterial function in humans, the investigators will
capitalize on the plasticity of the gut microbiome to dietary perturbations. A randomized,
single-blind, 2x1-week dietary intervention crossover study (with 3 week washout) will be
conducted in young (18-29 years) and old (60-79 years), exercising and non-exercising, male
and female adults from all races and ethnic backgrounds. Testing will take place on the
University of Colorado Boulder main campus at the Clinical and Translational Research Center
(CTRC - located in the Wardenburg Health Center). Subjects will undergo telephone and
in-person CTRC screening, with those eligible assigned to either Group A or Group B using
block randomization stratified by age and exercise status. Group A will undergo isocaloric WD
feeding (high fat [40%], high sugar [25%], low fiber [15g], low nutrient) during Phase 1
(first 1-week treatment period) and non-WD feeding (low-fat [25%], low sugar [15%], high
fiber [22g], high nutrient) during Phase 2 (second 1-week treatment period). Group B will
undergo the dietary interventions in the opposite order. Phases 1 and 2 will be separated by
a 3-week washout period to prevent carry over effects. During each 1-week intervention
period, fecal swabs will be collected daily to characterize the gut microbiome and vascular
function, will be measured at baseline and after 2 and 7 days of controlled feeding to gain
insight into the temporal relation between these outcomes.

Inclusion Criteria:

- Age 18-29 or 60-79 years

- Participating in < 30 min aerobic exercise < 2x/wk for >3 years OR > 45 min vigorous
aerobic exercise > 4x/wk for > 3 yrs

- Currently consuming levels of dietary fat intake with the 40th-60th percentile of
Americans based on the NHANES survey (29-37% calories from fat)

- Healthy (no clinical disease)

- Body mass index < 30 kg/m2

- Ankle-brachial blood pressure index > 0.9

- Total cholesterol < 240 mg/dl

- Fasting plasma glucose < 110 mg/dl

- Weight stable in the past 6 months

Exclusion Criteria:

- Current or past (within 3 months of screening) use of dietary supplements,
anti-inflammatory medications, drugs known to affect the gut microbiome (antibiotics,
pre/probiotics, antifungals, antivirals, antiparasitics), or gastrointestinal-targeted
drugs (proton pump inhibitors, H2 receptor antagonists, laxatives, antidiarrheal
medications)

- Current of past (within 5 years) smoking

- Major change in health status in the last 6 months

- Chronic clinical diseases (e.g., inflammatory bowl diseases, cardiovascular disease,
diabetes, neurological disorders, dementia or other brain diseases of aging)
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Boulder, Colorado 80309
(303) 492-1411
Phone: 303-735-6410
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