Effects of Red Beetroot Juice on High-Fat Meal-Induced Endothelial Dysfunction and Cardiometabolic Disturbances

Study Overview
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Brief Summary
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Aside from aging, numerous factors increase the risk for developing cardiovascular disease (CVD) including diet and nutrition. High-fat meal consumption induces postprandial vascular endothelial dysfunction and other cardiometabolic disturbances (e.g. dyslipidemia and hyperglycemia) in normal weight individuals and is exacerbated in overweight/obese individuals. These postprandial responses are likely largely due to activation of pro-inflammatory and pro-oxidant pathways. Given that much of the day is spent in the postprandial state, this may further impair cardiovascular health in aging overweight/obese individuals. Interventions that attenuate these responses are needed. Red beetroot (Beta vulgaris L.) is an excellent source of bioactive compounds including nitrate, flavonoids, phenolic acids, betalains, carotenoids, and ascorbic acid. These bioactive compounds and their metabolites have been shown to have antioxidative, anti-inflammatory, and cardiovascular-protective effects. These effects, particularly the cardiovascular-protective effects, have been primarily attributed to its high content of nitrate since it is converted to nitric oxide independent of the vascular endothelium via the enterosalivary nitrate-nitrite-nitric oxide pathway. However, red beetroot juice contains a number of other potentially beneficial bioactive compounds and few studies have aimed to determine whether these compounds work independently, additively, or synergistically in exerting these effects. Given the findings of previously conducted research in the broad area of red beetroot juice consumption and human health, it can be suggested that: 1) acute red beetroot juice consumption may prevent or attenuate the adverse postprandial responses to consuming a high-fat meal in individuals with exaggerated responses; and 2) chronic consumption of red beetroot may improve underlying factors contributing to these exaggerated responses. Accordingly, this project aims to: 1) investigate the efficacy of acute and chronic whole red beetroot juice consumption compared with its bioactive components in attenuating postprandial vascular endothelial dysfunction and adverse cardiometabolic responses to a high-fat meal; and 2) to gain insight into the underlying mechanisms responsible.

Detailed Description
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This is a randomized, double-blind, placebo-controlled, 4-period, 4-week crossover pilot clinical trial consisting of 2 postprandial tests for each period. Overweight or obese postmenopausal women and men aged 40 to 65 will be recruited from the greater Fort Collins, CO area. After telephone prescreening, participants will report to the study site for their first visit (Screening) where they will receive verbal and written explanation of the project, provide informed consent, followed by screening assessments. Qualified participants will be scheduled for a baseline visit and randomly assigned to their respective treatments. On the second visit (Baseline) following an overnight fast, anthropometrics and blood pressure will be measured and diet and physical activity records will be collected. Subjects will ingest their respective treatment 10 min prior to consuming the high-fat test meal. Various assessments will be performed and samples collected prior to and up to 4 hours post-meal consumption. At the third visit (Final), all assessments and sample collections will be repeated at the same time points but 24 hours after consuming the last dose of their respective treatments to test chronic rather than acute effects. Subjects will undergo a 4-week washout period before crossing over to the next treatment period. This will be repeated for all 4 treatments.

Official Title
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Acute and Chronic Effects of Red Beetroot Juice on High-Fat Meal-Induced Endothelial Dysfunction and Cardiometabolic Disturbances

Conditions
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Overweight, Obesity, Aging, Menopause

Intervention / Treatment
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* Dietary Supplement: 70 mL red beetroot juice
* Dietary Supplement: 70 mL red beetroot juice without nitrate
* Dietary Supplement: 70 mL placebo drink plus potassium nitrate
* Dietary Supplement: 70 mL placebo drink


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Postmenopausal women and men BMI between 25 and 40 kg/m2 Exclusion Criteria: Hypertension, cardiovascular disease, diabetes, cancer, or kidney, liver, or pancreatic disease Individuals taking gastroesophageal reflux, antihypertensive, hypoglycemic, lipid-lowering, hormone replacement, erectile dysfunction medications or nitrates Participating in a weight loss program or actively trying to lose weight Smokers Heavy drinkers (> 3 drinks on any given occasion and/or > 7 drinks/week for women, or > 4 drinks on any given occasion and/or > 14 drinks/week for men) Allergy to meals/treatments Consuming > 2 servings red beetroot or beetroot juice/wk

Ages Eligible for Study
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Minimum Age: 40 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: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 70 mL red beetroot juice<br>70 mL red beetroot juice naturally containing 300 mg nitrate. | Dietary Supplement: 70 mL red beetroot juice<br>* 1x daily intake of 70 mL red beetroot juice<br>|
| Active Comparator: 70 mL placebo drink plus potassium nitrate<br>70 mL calorie-matched placebo control drink containing 489 mg potassium nitrate to deliver 300 mg nitrate. | Dietary Supplement: 70 mL placebo drink plus potassium nitrate<br>* 1x daily intake of 70 mL placebo control drink plus 489 mg potassium nitrate (300 mg nitrate)<br>|
| Active Comparator: 70 mL red beetroot juice without nitrate<br>70 mL red beetroot juice per day without nitrate. | Dietary Supplement: 70 mL red beetroot juice without nitrate<br>* 1x daily intake of 70 mL red beetroot juice without nitrate<br>|
| Placebo Comparator: 70 mL placebo drink<br>70 mL calorie-matched placebo control drink devoid of nitrate, vitamins, minerals, and polyphenols. | Dietary Supplement: 70 mL placebo drink<br>* 1x daily intake of 70 mL placebo control drink<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Vascular endothelial function | Vascular endothelial function will be assessed using reactive hyperemia index (EndoPAT) 0 and 4 hours post-meal consumption. | 0 and 4 hours post-meal consumption at baseline and 1 month for each treatment period. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood glucose, insulin, and indices of insulin sensitivity and resistance | Blood glucose and insulin will be measured by biochemical analysis at 0 and 1, 2, and 4 hours post-meal consumption and indices of insulin sensitivity and resistance will be calculated. | 0 and 1, 2, and 4 hours post-meal consumption at baseline and 1 month for each treatment period. | 
| Blood triglycerides | Blood triglycerides will be measured by biochemical analysis at 0 and 1, 2, and 4 hours post-meal consumption. | 0 and 1, 2, and 4 hours post-meal consumption at baseline and 1 month for each treatment period. | 
| Blood pressure | Peripheral and central blood pressure measured by an automatic sphygmomanometer and SphygmoCor at 0 and 1, 2, and 4 hours post-meal consumption. | 0 and 1, 2, and 4 hours post-meal consumption at baseline and 1 month for each treatment period | 
| Heart rate | Heart rate will be measured by an automatic sphygmomanometer and SphygmoCor at 0 and 1, 2, and 4 hours post-meal consumption. | 0 and 1, 2, and 4 hours post-meal consumption at baseline and 1 month for each treatment period. | 
| Arterial stiffness | Arterial stiffness will be assessed as carotid-femoral pulse wave velocity and augmentation index (using SphygmCor and EndoPAT) at baseline and 1 month periods (pre-meal consumption). | Pre-meal consumption at baseline and 1 month for each treatment period. | 
| Nitric oxide biomarkers | Nitric oxide metabolites and molecules involved in nitric oxide production and bioavailability will be evaluated in saliva, blood, peripheral blood mononuclear cells, and biopsied venous endothelial cells at 0 and 1, 2, and 4 hours post-meal consumption. | 0 and 1, 2, and 4 hours post-meal consumption at baseline and 1 month for each treatment period. | 
| Oxidative stress biomarkers | Biomarkers of oxidative stress will be evaluating in peripheral blood mononuclear cells and biopsied venous endothelial cells at 0 and 1, 2, and 4 hours post-meal consumption. | 0 and 4 hours post-meal consumption at baseline and 1 month for each treatment period. | 
| Pro-inflammatory biomarkers | Biomarkers of inflammation will be evaluating in peripheral blood mononuclear cells and biopsied venous endothelial cells at 0 and 4 hours post-meal consumption. | 0 and 4 hours post-meal consumption at baseline and 1 month for each treatment period. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Red beetroot, Dietary Nitrate, Polyphenols, Endothelial Function, High-Fat Meal, Overweight, Obesity, Aging, Cardiometabolic