Effects of Nitrate in Vegetables on Blood Pressure in Subjects With Prehypertension

Study Overview
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Brief Summary
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The purpose of this study is to examine the effect of different vegetables on cardiovascular function in subjects with moderately increased blood pressure. Specifically we are comparing the effects of vegetables with a high natural content of inorganic nitrate with those of vegetables with a low nitrate content.

Detailed Description
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Recent studies indicate that dietary-derived inorganic nitrate can affect blood pressure in humans by converting into nitric oxide bioactivity. Here we will study if vegetables that naturally contain high amounts of nitrate (green leafy vegetables) can lower blood pressure and whether any effect is attributed to the nitrate anion. High nitrate vegetables are compared with vegetables low in nitrate (e.g. tomatoes, sweet pepper). After a 2 week run in period where all subjects receive vegetables low in nitrate, the participants are randomized to one of three interventions. One third of the patients receive high-nitrate vegetables + a placebo pill (KCl), one third receives low-nitrate vegetables + placebo and the third group receives low-nitrate vegetables + a nitrate pill (KNO3). The nitrate content in the pill is precisely matched to the nitrate content in the high-nitrate vegetable group.

Official Title
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Diet and Nitric Oxide (DINO): A Study on the Effects of Dietary Nitrate on Blood Pressure in Subjects With Prehypertension

Conditions
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Hypertension, Cardiovascular Disease

Intervention / Treatment
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* Other: High nitrate vegetables
* Dietary Supplement: Low nitrate vegetables + nitrate
* Other: Low nitrate vegetables


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 50-70 years Systolic blood pressure >130 at screening visit 2 Exclusion Criteria: Systolic blood pressure <120 or >159 mm Hg at screening 2 Systolic blood pressure > 169 mm Hg at screening 1 Chronic kidney disease Chronic rheumatic disease Insulin treated diabetes mellitus Atrial fibrillation Major cardiovascular event within 6 months Inflammatory bowel disease Malignancy, actively treated within 6 months Hepatitis Polycytemia Vera

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 70 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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: High nitrate vegetables<br>During 5 weeks subjects receive 100-150 g of a leafy green vegetable (High nitrate vegetables) per day and placebo pills containing 300 mg KCl (2 x 150 mg). | Other: High nitrate vegetables<br>* vegetables naturally high in nitrate<br>|
| Placebo Comparator: Low nitrate vegetables<br>During 5 weeks subjects receive 100-150 g of tomatoes/sweet pepper (Low nitrate vegetables) per day and placebo pills containing 300 mg KCl (2 x 150 mg). | Other: Low nitrate vegetables<br>* vegetables naturally low in nitrate<br>|
| Active Comparator: Low nitrate vegetables + nitrate<br>During 5 weeks subjects receive 100-150 g of tomatoes/sweet pepper (Low nitrate vegetables) per day and nitrate pills containing 300 mg KNO3 (2 x 150 mg). | Dietary Supplement: Low nitrate vegetables + nitrate<br>* pill containing KNO3<br>* Other names: potassium nitrate (KNO3);|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in Change in ambulatory Systolic Blood Pressure From Baseline | Measure how 24h ambulatory SBP changes over 5 weeks with the different interventions | 5 weeks intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in Change in ambulatory diastolic Blood Pressure From Baseline | Measure how 24h ambulatory DBP changes over 5 weeks with the different interventions | 5 weeks intervention | 
| Difference in Change in office diastolic blood pressure (DBP) | BP is measured during a hospital visit every week during intervention | Once every week for 5 weeks | 
| Difference in Change in flow mediated dilatation (FMD) | FMD is measured before and after the interventions | 5 weeks intervention | 
| Difference in Change in office Systolic Blood Pressure From Baseline | Measure how clinic SBP changes weekly over 5 weeks with the different interventions | 5 weeks intervention | 
| Difference in Change in Daytime Ambulatory systolic Blood Pressure From Baseline | Measure how 24h ambulatory daytime SBP changes over 5 weeks with the different interventions | 5 weeks intervention |