Effect of Lettuce With Different Nitrate Contents on Blood Pressure

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.

Conditions

• Dietary Modification
• Blood Pressure

Interventions

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).

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).

Sponsors & Collaborators

• Newcastle University

  lead OTHER

Principal Investigators

• AFRD School · School of Agriculture, Food and Rural development

Study Design

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

QUADRUPLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

35 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2015-04-30

Primary Completion

2015-08-31

Completion

2015-08-31

Countries

• United Kingdom

Study Locations