Effect of Lettuce With Different Nitrate Contents on Blood Pressure (LBP)
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|ClinicalTrials.gov Identifier: NCT02701959|
Recruitment Status : Completed
First Posted : March 8, 2016
Last Update Posted : May 23, 2016
Leafy vegetables are a natural source of dietary nitrate, which may reduce systolic blood pressure (BP). However, the evidence has been obtained from studies using nitrate solutions (i.e., potassium or sodium nitrate) or beetroot juice supplementation which have a suitable placebo for the design of double-blind clinical trials. However, the design of food-based nutritional interventions is complicated by the fact that an appropriate placebo treatment is not available and, therefore, it is not possible to meet the criteria for proper double-blind randomised placebo-controlled intervention trials. In addition, the biological effects of processed products such as beetroot juice or solutions with a pharmacological grade may be different from that of fresh vegetables, e.g. due to conversion of nitrate to nitrite in the mouth during chewing.
Objectives: to investigate whether two sets of lettuce specifically grown with different nitrate content but otherwise similar composition show different effects on nitrate uptake and bioavailability in humans. Additionally, the investigators also aim to design human intervention studies to investigate the effect of intake of lettuce with different nitrate content on vascular health.
These objectives will be tested by growing lettuce with different fertiliser compositions resulting in high and low nitrate content and then investigating the bioavailability and short-term effect on BP in healthy young volunteers in a double-blind cross-over design. Eligible subjects will consume one meal each of either low or high nitrate lettuce. Urine, blood and saliva samples will be collected at baseline, for 6 hours after the ingestion and then again after 24hr. Blood Pressure BP will be measured continuously for 24 hours starting at baseline. The volunteers will repeat the intervention with the second treatment.
|Condition or disease||Intervention/treatment||Phase|
|Dietary Modification Blood Pressure||Dietary Supplement: High Nitrate Lettuce Dietary Supplement: Low Nitrate Lettuce||Phase 1 Phase 2|
Show Detailed Description
|Study Type :||Interventional (Clinical Trial)|
|Actual Enrollment :||20 participants|
|Intervention Model:||Crossover Assignment|
|Masking:||Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)|
|Official Title:||Growth of Lettuce With Different Content of Inorganic Nitrate as a Feeding Strategy for Placebo-controlled Nutritional Interventions to Test the Effects of Inorganic Nitrate on Human Health|
|Study Start Date :||April 2015|
|Actual Primary Completion Date :||August 2015|
|Actual Study Completion Date :||August 2015|
Placebo Comparator: Low nitrate lettuce
50g of low nitrate lettuce (placebo) on single occasions
Dietary Supplement: Low Nitrate Lettuce
The lettuce has been grown with low concentration of nitrogen fertilizer (25ppm) to produce the low amount of nitrate in the lettuce, the nitrate content of 50 grams of high nitrate lettuce was (~3 mg nitrate derived).
Active Comparator: High nitrate lettuce
50g of high nitrate lettuce (intervention) on single occasions
Dietary Supplement: High Nitrate Lettuce
The lettuce has been grown with high concentration of nitrogen fertilizer (150ppm) to produce the high of nitrate content in the lettuce, the nitrate content of 50 grams of high nitrate lettuce was (~530 mg nitrate derived).
- Change in 24-hour Ambulatory Blood Pressure (AMBP) [ Time Frame: Baseline and 24 hours ]Change in Systolic and Diastolic Blood Pressure at baseline and every 30 minutes at day time and every hour at night time for 24 hours.
- Change in bio-availability of nitrate and nitrite in plasma [ Time Frame: 24 hours ]Change in plasma nitrate and nitrite at baseline, 3 hours, 6 hours and 24 hours from intervention.
- Change in Cyclic Guanosine Monophosphate (cGMP) in plasma samples [ Time Frame: 24 hours ]Change in Cyclic Guanosine Monophosphate (cGMP) in plasma samples at baseline, 3 hours, 6 hours and 24 hours from intervention.
- Change in bio-availability of nitrate and nitrite in urine samples [ Time Frame: 24 hours ]Change in urinary nitrate and nitrite at baseline, 0-3, 3-6, 6-12 and 12-24 hours from intervention.
- Change in bio-availability of nitrate and nitrite in saliva samples [ Time Frame: 24 hours ]Change in salivary nitrate and nitrite at baseline, 0, 1, 2, 3, 4, 5, 6, 9, 12 and 24 hours from intervention.
- Change in Antioxidant capacity of Ferric Reducing Antioxidant Power (FRAP) and Trolox Equivalent Antioxidant Capacity (TEAC) in plasma samples. [ Time Frame: 24 hours ]Change in Antioxidant capacity of Ferric Reducing Antioxidant Power (FRAP) and Trolox Equivalent Antioxidant Capacity (TEAC) in plasma samples at baseline, 3 hours, 6 hours and 24 hours from intervention.
To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02701959
|School of Agriculture, Food and Rural Development|
|Newcastle upon Tyne, England, United Kingdom, NE1|
|Study Director:||AFRD School||School of Agriculture, Food and Rural development|