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Effects of Freeze Dried Strawberry Powder Supplementation on Cardiovascular Risk Factors and Gut Microbiome

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. Identifier: NCT03522974
Recruitment Status : Recruiting
First Posted : May 14, 2018
Last Update Posted : September 6, 2019
Information provided by (Responsible Party):
Ann Skulas-Ray, University of Arizona

Brief Summary:
Dietary interventions designed to promote health by increasing the consumption of particular health-promoting foods (e.g., strawberries) generally target blood pressure and LDL-C; however, CVD risk reduction may also be achieved via changes in emerging endpoints such as the gut microbiome. Previous research suggests that strawberries have the potential to reduce LDL-C, but it remains unclear whether there is a dose-response relationship. Moreover, few studies have evaluated effects on vascular health or characterized changes in the gut microbiome following daily strawberry consumption. Additionally, previous studies have largely been conducted among Caucasian populations. Given the demographics of the US, it is important to evaluate effects in study populations that include ethnicities that may have higher risk of type 2 diabetes and/or other CVD risk factors, such as Hispanics. This study aims to examine the effects of 4 weeks of supplementation with two doses of freeze dried strawberry powder (low dose: 13 g/d and high dose: 40 g/d) on: 1) LDL-C and blood pressure; 2) gut microbiome profile; and 3) other CVD and type 2 diabetes risk factors, including glucose, insulin, and inflammatory markers. Overweight (BMI 25-36 kg/m2) but otherwise healthy adults with moderately elevated LDL-C (>3.0 mmol/L) and/or prehypertension (120-159/80-99 mm Hg) will be enrolled. This will optimize the potential for observing significant benefits on these outcomes. 50 eligible participants will be recruited with the expectation that at least 40 will complete the study. The placebo-controlled, crossover study design will allow for a direct comparison of dose-response within the same participant. The investigators anticipate that the bioactive components of strawberries will reduce LDL-C and blood pressure, and modify the gut microbiome, with greater changes on the high dose. There is preliminary evidence that polyphenol-rich foods can modify gut microbiota profiles, but this would be the first study to characterize the effects of daily strawberry consumption. The investigators are uniquely placed at the University of Arizona to enroll a larger percentage of Hispanic participants, who are often under-represented in clinical nutritional research. Results from the proposed study will improve understanding of how strawberries might promote health, and could provide further support for the incorporation of whole freeze dried fruit in dietary guidelines.

Condition or disease Intervention/treatment Phase
Cardiovascular Risk Factor Dietary Supplement: Strawberry powder Dietary Supplement: Placebo powder Not Applicable

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 50 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary Purpose: Prevention
Official Title: Effects of Freeze Dried Strawberry Powder Supplementation on Vascular Function, Blood Markers of Cardiovascular Risk, and the Gut Microbiome
Estimated Study Start Date : November 1, 2019
Estimated Primary Completion Date : December 2020
Estimated Study Completion Date : December 2020

Arm Intervention/treatment
Placebo Comparator: Placebo
40 g/d placebo powder
Dietary Supplement: Placebo powder
40 g/d placebo powder matched for taste and appearance

Experimental: Strawberry powder (high dose)
40 g/d freeze dried strawberry powder
Dietary Supplement: Strawberry powder
Freeze dried strawberry powder

Active Comparator: Strawberry powder (low dose)
13 g/d freeze dried strawberry powder
Dietary Supplement: Strawberry powder
Freeze dried strawberry powder

Primary Outcome Measures :
  1. LDL-C/non-HDL-C [ Time Frame: 4-6 weeks ]
  2. Brachial and central blood pressure [ Time Frame: 4-6- weeks ]
    systolic and diastolic blood pressures

Secondary Outcome Measures :
  1. Pulse Wave Velocity (PWV) [ Time Frame: 4-6 weeks ]
  2. Augmentation Index [ Time Frame: 4-6 weeks ]
    augmentation index corrected for heart rate

  3. Other lipids and lipoproteins [ Time Frame: 4-6 weeks ]
    HDL-C, total cholesterol, and triglycerides

  4. Glucose [ Time Frame: 4-6 weeks ]
    fasting glucose

  5. Insulin [ Time Frame: 4-6 weeks ]
    fasting insulin

Other Outcome Measures:
  1. Gut microbiome [ Time Frame: 4-6 weeks ]
    Composition of the gut microbial community measured by high-throughput 16S rRNA sequencing

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   30 Years to 65 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • At least one of the following:

    • LDL-C above 3.0 mmol/L (116 mg/dL)
    • Systolic blood pressure of 120-159 mmHg
    • Diastolic blood pressure of 80-99 mmHg
  • Total cholesterol below 6.2 mmol/L (240 mg/dL)
  • Triglycerides below 350 mg/dL

Exclusion Criteria:

  • Allergies to strawberries
  • History of CVD, Stage II hypertension (BP ≥ 160/100 mmHg), kidney disease, diabetes, or inflammatory diseases such as GI disorders and rheumatoid arthritis
  • Use of medications/supplements for elevated lipids, blood pressure, or glucose
  • Chronic use of non-steroidal anti-inflammatory or immunosuppressant drugs
  • Conditions requiring chronic use of steroids

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 identifier (NCT number): NCT03522974

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Contact: Chesney Richter, PhD 520-621-5382
Contact: Ann Skulas-Ray, PhD 520-621-2084

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United States, Arizona
University of Arizona Recruiting
Tucson, Arizona, United States, 85721
Contact: Ann Skulas-Ray         
Sponsors and Collaborators
University of Arizona
  Study Documents (Full-Text)

Documents provided by Ann Skulas-Ray, University of Arizona:
Informed Consent Form  [PDF] February 23, 2018

U.S. Department of Health and Human Services and U.S. Department of Agriculture, 2015-2020 Dietary Guidelines for Americans, 2015.

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Responsible Party: Ann Skulas-Ray, Assistant Professor of Nutritional Sciences, University of Arizona Identifier: NCT03522974    
Other Study ID Numbers: Strawberry Study
First Posted: May 14, 2018    Key Record Dates
Last Update Posted: September 6, 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