None listed
Conditions
Brief summary
The primary objective of this study is to determine if regular consumption of nitrate-rich green leafy vegetables can reduce blood pressure in men and women with high-normal blood pressure. We will also investigate the claim that dietary nitrate contributes to the body’s NO stores and that these stores represent a physiologically relevant reservoir of NO.
Interventions
A randomised, controlled, cross-over design trial will be performed.
Trial periods
1. Run-in (washout) period: 1 week.
All participants will begin the trial consuming a low nitrate/low green leafy vegetable (usual) diet (containing less than ~100 mg/d of nitrate).
2. First intervention period: 1 week.
Participants will then either: continue on the low nitrate diet; or increase the intake of green leafy vegetables resulting in an estimated nitrate intake of greater than 400 mg/d.
3. Washou
A randomised, controlled, cross-over design trial will be performed. Trial periods 1. Run-in (washout) period: 1 week. All participants will begin the trial consuming a low nitrate/low green leafy vegetable (usual) diet (containing less than ~100 mg/d of nitrate). 2. First intervention period: 1 week. Participants will then either: continue on the low nitrate diet; or increase the intake of green leafy vegetables resulting in an estimated nitrate intake of greater than 400 mg/d. 3. Washout period: 1 week. As for 1 above 4. Second intervention period: 1 week. As for 2 above The order of the two interventions (low nitrate; high nitrate) will be randomized. Diets 1. The low nitrate (usual) diet will involve reducing green leafy vegetables as well as a limited number of other foods rich in nitrate (beetroot, celery, parsley) in the diet, but only if this is required to limit nitrate intake to less than ~100 mg/d. The average nitrate intake in Western populations is often well under 100 mg/d, so for most participants there will be minimal change to their diet and nitrate intake; and 2. The high nitrate diet will involve adding green leafy vegetables to the diet. Leafy greens added to the diet will include: spinach (dried and powdered, fresh and frozen); lettuce (all types); rocket; and Chinese greens (such as bok choy; choy sum, Chinese cabbage). To enhance compliance participants will be provided with all intervention foods (frozen and fresh).The objective will be to include at least 300 g/d of green leafy vegetables into the diet, increasing estimated nitrate intake to greater than 400 mg/d. A dietitian will provide individual advice on how to include the green leafy vegetables without altering energy or macronutrient intakes.
Sponsors
University of Western Australia
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Prevention
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
20 Years to 70 Years
Healthy volunteers
Yes
Inclusion criteria
Men and women aged 20 to 70 years with high-normal blood pressure (systolic blood pressure 120-139 mm Hg or diastolic blood pressure 80-89 mm Hg)
Exclusion criteria
Use of antihypertensive medication; systolic blood pressure < 120 mm Hg or > 139 mm Hg and diastolic blood pressure <80 mm Hg or >89 mm Hg; a diet high in green leafy vegetables; use of antibacterial mouth wash (which kills bacteria responsible for nitrate reduction in the mouth); use of antibiotics (within previous 2 months); current or recent (<12 months) smoking; history of cardiovascular or peripheral vascular disease; recent history of a psychiatric illness or other major illnesses such as cancer; recent history of asthma, renal, liver or gastrointestinal disease, or gout; a change in drug therapy within the previous 3 months, or the likelihood that drug therapy would change during the study; current or recent (within previous 6 months) significant weight loss or gain (> 6% of body weight); alcohol intake > 140 g per wk; reported participation in night shift work during the study period; and inability or unwillingness to follow the study protocol.
Outcome results
None listed