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
试验速览
- 阶段
- 1 期
- 状态
- 已完成
- 入组人数
- 20
- 试验地点
- 2
- 主要终点
- Change in 24-hour Ambulatory Blood Pressure (AMBP)
研究概览
简要总结
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.
详细描述
Study Design and Subjects: This study is designed as a double-blind, randomized, crossover, intervention trial in which thirty healthy young volunteers (BMI: 20-25 kg/m2), non-smoking subjects (age: 18-35 years) will be recruited. In each of two intervention periods, subjects will be asked to eat 50g of either high nitrate lettuce or low nitrate lettuce (placebo) on a single occasion (the second visit) with dietary restriction for 3 days prior to the second visit and in the 24 hr period following after the consumption, concluded with a third visit, with at least 3 weeks washout period before the second 2-day intervention period. Urine, saliva and blood samples will be collected during a 6-hour period during the second visit. Urine samples will be collected during 24h from consumption until the third visit, to assess the pharmacokinetics and bioavailability and compliance to the interventions (details in the diagram of human trial).
The primary outcomes are 24-hour BP and nitrate content in urine, plasma and saliva. Samples will be collected into tubes and then analysed in the laboratory for the nitrate content (NO3-) by gas chromatography-mass spectroscopy (GCMS). Participants will follow specific dietary and lifestyle instructions to minimise confounding effects.
Participant will receive a small honorarium after the study and reasonable travel expenses will be reimbursed.
Dietary Interventions: Participants will be asked to arrive fasting in the morning of the second (main) visit and will consume a standard meal (Chicken Hotpot from ASDA) with the same drink water at the evening before and the evening after the visit, as well as following a diet that excludes a list of specific foods containing high nitrate (rocket, spinach, other leafy vegetables, radish and beet root), cured meat, cured seafood and cured fish, mature cheese for 24hr prior to the study and fasting on the morning of the study.
Anthropometry: This includes the measurements of body weight, height and waist circumference according to standardised protocols. Procedures are safe, not invasive and induce minimal discomfort for the participants.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Prevention
- 盲法
- Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
入排标准
- 年龄范围
- 18 Years 至 35 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- 未提供
排除标准
- 未提供
结局指标
主要结局
Change in 24-hour Ambulatory Blood Pressure (AMBP)
时间窗: 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.
次要结局
- Change in bio-availability of nitrate and nitrite in plasma(24 hours)
- Change in Cyclic Guanosine Monophosphate (cGMP) in plasma samples(24 hours)
- Change in bio-availability of nitrate and nitrite in urine samples(24 hours)
- Change in bio-availability of nitrate and nitrite in saliva samples(24 hours)
- Change in Antioxidant capacity of Ferric Reducing Antioxidant Power (FRAP) and Trolox Equivalent Antioxidant Capacity (TEAC) in plasma samples.(24 hours)