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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
Sponsor:
Information provided by (Responsible Party):
Newcastle University

Brief Summary:

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

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 20 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Prevention
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

Arm Intervention/treatment
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).




Primary Outcome Measures :
  1. 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.


Secondary Outcome Measures :
  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.



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Ages Eligible for Study:   18 Years to 35 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion criteria:

The investigators aim to recruit 20 healthy young volunteers, non-smoking, male and female aged 18-35 years with a body mass index (BMI) in the range of 20 to 25 kg/m2.

Exclusion criteria (reason for exclusion):

  • Current participation in other clinical investigations.
  • Mouthwash users.
  • Vegetarianism (likely to have very high nitrate intake)
  • Dislike to lettuce consumption or inability to comply with the study diet (lack of compliance)
  • Use of antihypertensive or cholesterol lowering medication.
  • History of any major illness such as cancer; or cholesterol lowering medication; history of cardiovascular or peripheral vascular disease;
  • History of any major illness such as cancer; a psychiatric illness; recent history of asthma, renal, liver or gastrointestinal disease.
  • Use of antibiotics within previous 2 months; current or recent (within previous 6 months) significant weight loss or gain (>6% of body weight); --woman who were pregnant, lactating or wishing to become pregnant during the study.
  • Previous diagnosis of type 1 or type-2 diabetes treated with insulin (modification of regulation of intermediate metabolism).
  • Major surgical operations interfering with the study outcomes (systemic effects on study outcomes).
  • Alcohol intake >21 units/week for men and >14 units/week women
  • Non English speakers or volunteers requiring translators or interpreters (since these services are not available for this study).

Information from the National Library of Medicine

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


Locations
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United Kingdom
School of Agriculture, Food and Rural Development
Newcastle upon Tyne, England, United Kingdom, NE1
Sponsors and Collaborators
Newcastle University
Investigators
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Study Director: AFRD School School of Agriculture, Food and Rural development

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Responsible Party: Newcastle University
ClinicalTrials.gov Identifier: NCT02701959     History of Changes
Other Study ID Numbers: 15-QAD-15
First Posted: March 8, 2016    Key Record Dates
Last Update Posted: May 23, 2016
Last Verified: May 2016
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Plan Description: I can't share the individual participants data because of the privacy of volunteers have been participated in this study and this already been mentioned in the application form of ethical approval.
Keywords provided by Newcastle University:
Nitric oxide
Dietary intervention trail