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

Study Overview
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Brief Summary
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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.

Official Title
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Effects of Freeze Dried Strawberry Powder Supplementation on Vascular Function, Blood Markers of Cardiovascular Risk, and the Gut Microbiome

Conditions
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Cardiovascular Risk Factor

Intervention / Treatment
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* Dietary Supplement: Strawberry powder
* Dietary Supplement: Placebo powder


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 30 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Placebo<br>40 g/d placebo powder | Dietary Supplement: Placebo powder<br>* 40 g/d placebo powder matched for taste and appearance<br>|
| Experimental: Strawberry powder (high dose)<br>40 g/d freeze dried strawberry powder | Dietary Supplement: Strawberry powder<br>* Freeze dried strawberry powder<br>|
| Active Comparator: Strawberry powder (low dose)<br>13 g/d freeze dried strawberry powder | Dietary Supplement: Strawberry powder<br>* Freeze dried strawberry powder<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| LDL-C/non-HDL-C |  | 4-6 weeks | 
| Brachial and central blood pressure | systolic and diastolic blood pressures | 4-6- weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pulse Wave Velocity (PWV) |  | 4-6 weeks | 
| Augmentation Index | augmentation index corrected for heart rate | 4-6 weeks | 
| Other lipids and lipoproteins | HDL-C, total cholesterol, and triglycerides | 4-6 weeks | 
| Glucose | fasting glucose | 4-6 weeks | 
| Insulin | fasting insulin | 4-6 weeks |