Blood Pressure, High, Hypertension
Conditions
Keywords
nitrate, vegetables
Brief summary
The project aims to determine the effect of a high-nitrate dietary intervention on blood pressure and markers of vascular function compared to a low-nitrate intervention in people with elevated blood pressure. Half of the participants will receive the high-nitrate dehydrated vegetable intervention, while the other half will receive the low-nitrate dehydrated vegetable intervention.This project will advance the current hypothesis on the therapeutic link between dietary nitrate and high blood pressure, and potentially derive impactful recommendations for individuals at risk of hypertension.
Detailed description
Diets rich in fruits and in particular, vegetables, reduce blood pressure (BP) and the risk of cardiovascular events. Increasingly, attention is being given to high-nitrate containing vegetables, with emerging evidence that it might represent a source of vasoactive nitric oxide. Clinical data to date uniformly suggest an acute vasoprotective role of dietary nitrate administration and a BP-lowering effect. Whether the vascular effects extend to long-term intake and in individuals with elevated blood pressure is not well known. The investigators hypothesize that consumption of a dietary intervention high in nitrate from vegetable sources will have a greater effect on BP and related vascular parameters than a similar intervention that is low in dietary nitrates.
Interventions
OTHERHigh-nitrate dehydrated vegetable powder
A mixed combination of vegetable powders that are naturally high in nitrate content, such as beet, spinach, and kale
OTHERLow-nitrate dehydrated vegetable powder
A mixed combination of vegetable powders that are naturally low in nitrate content, such as peas, tomato, broccoli, carrots, and brussel sprouts
Sponsors
Canadian Institutes of Health Research (CIHR)
Unity Health Toronto
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Masking description
Participants and study coordinators will be blinded to the nature of the treatment allocation. Stratified randomization lists by baseline sex and age will be created.
Intervention model description
The study will be a randomized, double-blind, controlled parallel study. There will be two experimental arms of 16-week duration, in which participants are assigned to test or control arms under free living conditions in an outpatient setting.
Eligibility
Sex/Gender
ALL
Age
30 Years to 60 Years
Healthy volunteers
No
Inclusion criteria
* BMI 18.5-35 kg/m2 * Seated systolic blood pressure ≥130 and \<160 mmHg
Exclusion criteria
* current use of antihypertensive agents * history of major cardiovascular events in the last 1 year (stroke or myocardial infarction) * stage II hypertension as per JNC7 criteria (systolic BP/ diastolic BP ≥160/100 mmHg) - angina pectoris * gastrointestinal (i.e. inflammatory bowel disease, celiac), liver or kidney disease * cardiac condition that compromises normal function (e.g. mitral valve disease, heart failure) * serum triglyceride \>4.5mmol/L * major disability or disorder requiring continuous medical attention * planned initiation in antihypertensive therapy * herb or supplement use that may affect primary outcome * consuming \>3 servings of vegetables/day (based on semi-quantitative food frequency questionnaire) * alcohol use \>2 drinks/day * chronic or prescribed use of medications including prescription NSAIDs, antacids, warfarin, medications affecting NO synthesis (ie. sildenafil, organic nitrates, etc) * use of antibiotics within 3-months of the study start * participants should also be willing to refrain from using mouthwash (ie chlorhexidine) for the duration of their participation in the study
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Systolic Blood Pressure | Baseline, 8 and16 weeks | Change in systolic blood pressure vs. control at 16 weeks |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Aortic Systolic and Diastolic Blood Pressure | Baseline, 8 and 16 weeks | Change in aortic systolic and diastolic blood pressure vs. control at 16 weeks |
| Pulse Wave Velocity (PWV) | Baseline and 16 weeks | Change in PWV vs. control at 16 weeks |
| Mean 24h and Daytime Ambulatory Systolic, Diastolic and Mean Arterial Blood Pressure | Baseline and 16 weeks | Change in mean 24h and daytime ambulatory systolic, diastolic and mean arterial blood pressure vs. control at 16 weeks |
| High Sensitivity C-reactive protein (hs-CRP) | Baseline and 16 weeks | Change in hs-CRP vs. control at 16 weeks |
| Plasma Lipids | Baseline and 16 weeks | Change in Total-C, LDL-C, HDL-C vs. control at 16 weeks |
| Augmentation Index (AI) | Baseline, 8 and 16 weeks | Change in AI vs. control at 16 weeks |
Other
| Measure | Time frame | Description |
|---|---|---|
| Body Weight | Screening, baseline, 8 and 16 weeks | Body Weight in kg |
| 24h Urinary Nitrite and Nitrate levels (exploratory outcome, TBD) | 16 weeks | Marker of treatment compliance |
| 24h Urinary Potassium levels (exploratory outcome, TBD) | 16 weeks | Urine samples collected for estimation of potassium intake |
| Symptoms Diary | Screening, baseline, 8 and 16 weeks | Record of any adverse symptoms experienced and the level of severity |
| Cyclic guanosine monophosphate (cGMP) (exploratory outcome, TBD) | Baseline and 16 weeks | Change in cGMP vs. control at 16 weeks |
| Plasma nitrate/nitrite (exploratory outcome, TBD) | Baseline and 16 weeks | Change in plasma nitrate and nitrite vs. control at 16 weeks |
| 24h Urinary Sodium levels (exploratory outcome, TBD) | 16 weeks | Urine samples collected for estimation of sodium intake |
| Aspartate Aminotransferase (AST) | Screening, baseline, 8 and 16 weeks | Liver function test |
| Creatinine | Screening, baseline, 8 and 16 weeks | Kidney function test |
| Sachet Count | 8 and 16 weeks | Record of the amount of sachets and contents returned |
| 7-Day Food Record | Baseline, 8 and 16 weeks | Record of food intake 7 days prior to study visit day |
| Nitrate Food Frequency Questionnaire | Biweekly (screening, 0,2,4,6,8,10,12,14,16,18 weeks) | Assess consumption of nitrate-rich meats and vegetables |
| Habitual Physical Activity Questionnaire | Baseline, Week 16 | Questions to assess level of physical activity |
Countries
Canada
Contacts
Primary ContactElena Jovanovski, MSc
Backup ContactDandan Li, MSc (c)
Outcome results
None listed