The Effects of Types of Fruits and Vegetables on Vascular Function

Not Applicable

Completed

• Conditions: Vascular Stiffness; Blood Pressure; Cardiovascular Risk Factor
• Interventions: Other: CC; Other: LFV; Other: HFV

• Registration Number: NCT03410342
• Lead Sponsor: University of Cambridge

Brief Summary

The CIRCUS study is a randomised controlled, cross-over trial to evaluate the effects of increased intakes of citrus fruits and cruciferous vegetables on vascular function in 36 untreated, prehypertensive participants.

Detailed Description

The study comprises three 14-day dietary intervention periods, preceded by one week run-in period and separated by one week wash-out periods, 9 weeks in total. The diet will be fully controlled and provided by the researchers. Participants will receive in random order three interventions:

* 1 portion of fruits plus 1 portion of vegetables, of commonly consumed types per day. Intakes are at 25th percentile of UK consumption and will exclude citrus fruits, cruciferous and allium vegetables.

* 4 portions of fruits plus 4 portions of vegetables, of commonly consumed types per day excluding citrus fruits, cruciferous and allium vegetables.

* 4 portions of citrus fruits plus 4 portions of cruciferous vegetables per day.

Study Timeline

• Study Start: 2017-09-04
• Study First Submitted: 2017-12-03
• Study First Submitted QC: 2018-01-24
• Study First Posted: 2018-01-25
• Primary Completion: 2021-06-21
• Study Completion: 2021-06-21
• Status Verified: 2022-03
• Last Update Submitted: 2022-03-07
• Last Update Posted: 2022-03-22

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 36

Inclusion Criteria

• 40 - 65 years
• Average systolic blood pressure of 125-140 mmHg at 2 measurements separated by >30 minutes
• No use of antihypertensive medication
• No reported current or previous diabetes mellitus, (secondary) hypertension, or metabolic, cardiovascular, renal, liver, thyroid, gastrointestinal diseases
• Body Mass Index between 20 - 35 kg/m2
• Non-smoker
• Average fruit and vegetable consumption of <4 portions per day (UK average, 40-65 years), or willing to reduce habitual daily fruit and vegetable intake.

Exclusion Criteria

• Any medication likely to interfere with energy metabolism, appetite regulation and hormonal balance.

• Excessive alcohol intake of > 21 units per week (females) or >28 units per week (male) and not willing to limit alcohol intake to maximum of 1 unit/day

• Physical activity of >=10 hours/week of moderate to vigorous physical activity

• Weight loss or gain of >=3 kg in the preceding 3 months

• Use of dietary supplements or unwilling to stop supplement use >= 2 weeks before enrolment and during intervention

• Pregnancy or lactation

• Intervention specific factors, including:

  • Unable or unwilling to consume provided diets during the intervention
  • Unsufficient storage space for provided diets
  • Food sensitivities or vegetarian/vegan diet by choice
  • Participation in another intervention study at the same time
  • Living > 15 miles from the Imperial/NIHR Clinical Research Facility at Hammersmith Hospital
  • No signed informed consent

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
High Citrus fruits and Cruciferous vegetables (CC)	CC	4 portions of citrus fruits plus 4 portions of cruciferous vegetables per day excluding any other types of fruits and vegetables including allium vegetables.
Low Fruits and Vegetables (LFV)	LFV	1 portion of fruits plus 1 portion of vegetables, of commonly consumed types per day. Intakes are at 25th percentile of UK consumption (NDNS) and will exclude citrus fruits, cruciferous and allium vegetables.
High Fruits and Vegetables (HFV)	HFV	4 portions of fruits plus 4 portions of vegetables, of commonly consumed types per day excluding citrus fruits, cruciferous and allium vegetables.

Primary Outcome Measures

Name	Time	Method
Blood pressure	Measured on the morning after each of three recurring run-in periods and after each of three recurring 2-week intervention periods, 6 times total during 9 weeks	Changes in systolic and diastolic blood pressure (mmHg) measured by automated oscillometric device (average of 3 measurements).

Secondary Outcome Measures

Name	Time	Method
Circulatory metabolic profiles	Measured on the morning after each of three recurring run-in periods and after each of three recurring 2-week intervention periods, 6 times total during 9 weeks	(Un)targeted metabolic profiling by NMR and MS
Markers of low-grade inflammation measured in fasted blood samples	Measured on the morning after each of three recurring run-in periods and after each of three recurring 2-week intervention periods, 6 times total during 9 weeks	e.g. Interleukin-6
Urinary metabolic profiles	Measured on the morning after each of three recurring run-in periods and after each of three recurring 2-week intervention periods, 6 times total during 9 weeks	(Un)targeted metabolic profiling by NMR and MS
Faecal microbiome composition	Measured on the morning after each of three recurring run-in periods and after each of three recurring 2-week intervention periods, 6 times total during 9 weeks	Measured by 16SrRNA gene sequencing
Arterial stiffness	Measured on the morning after each of three recurring run-in periods and after each of three recurring 2-week intervention periods, 6 times total during 9 weeks	Changes (end minus baseline values) in arterial stiffness (pulse wave analysis)
Established objective markers of food intake	Measured on the morning after each of three recurring run-in periods and after each of three recurring 2-week intervention periods, 6 times total during 9 weeks	e.g. vitamin C
Markers of cardiometabolic health measured in fasted blood samples	Measured on the morning after each of three recurring run-in periods and after each of three recurring 2-week intervention periods, 6 times total during 9 weeks	e.g. high-density lipoprotein
Markers of endothelial function measured in fasted blood samples	Measured on the morning after each of three recurring run-in periods and after each of three recurring 2-week intervention periods, 6 times total during 9 weeks	e.g. C-Reactive Protein
Self-rated general health and mental well-being	Measured on the morning after each of three recurring run-in periods and after each of three recurring 2-week intervention periods, 6 times total during 9 weeks	e.g. Positive and Negative Affect Schedule (PANAS) that consists of two 10-item scales to measure both positive and negative affect. Each item is rated on a Likert scale of 1 (not at all) to 5 (very much). Positive and negative affect scores are added seperately to a reange from 10 to 50. Higher positive scores represents higher levels of positive affect. Lower negative scores respresaent lower levels of negative affect.
Cognitive function	Measured on the morning after each of three recurring run-in periods and after each of three recurring 2-week intervention periods, 6 times total during 9 weeks	e.g. Stroop-test

Trial Locations

Locations (2)

Cambridge Epidemiology & Trials Unit; 🇬🇧 Cambridge, United Kingdom

Imperial/NIHR Clinical Research Facility; 🇬🇧 London, United Kingdom