CIRCUS: The Effects of Types of Fruits and Vegetables on Vascular Function
Study Details
Study Description
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.
| Condition or Disease | Intervention/Treatment | Phase |
|---|---|---|
|
N/A |
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:
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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.
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4 portions of fruits plus 4 portions of vegetables, of commonly consumed types per day excluding citrus fruits, cruciferous and allium vegetables.
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4 portions of citrus fruits plus 4 portions of cruciferous vegetables per day.
Study Design
Arms and Interventions
| Arm | Intervention/Treatment |
|---|---|
| Placebo Comparator: Low Fruits and Vegetables (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. |
Other: LFV
1 apple/banana/small bunch of grapes per day plus 1 portion of carrot/pepper/tomato per day
|
| Experimental: High Fruits and Vegetables (HFV) 4 portions of fruits plus 4 portions of vegetables, of commonly consumed types per day excluding citrus fruits, cruciferous and allium vegetables. |
Other: HFV
4 portions of fruits (apples, bananas, grapes, pears) plus 4 portions of vegetables (carrots, cucumber, sweet peppers, tomatoes), of commonly consumed types per day excluding citrus fruits, cruciferous and allium vegetables.
|
| Experimental: High Citrus fruits and Cruciferous vegetables (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. |
Other: CC
4 portions of citrus fruits (clementines, grapefruits, lemons, oranges) plus 4 portions of cruciferous vegetables (broccoli, brussels sprouts, cauliflower, kale, savoy cabbage) per day.
|
Outcome Measures
Primary Outcome Measures
- 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
- 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)
- 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
- 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
- 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
- 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
- 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
- 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
- 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.
Eligibility Criteria
Criteria
Inclusion Criteria:
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40 - 65 years
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Average systolic blood pressure of 125-140 mmHg at 2 measurements separated by >30 minutes
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No use of antihypertensive medication
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No reported current or previous diabetes mellitus, (secondary) hypertension, or metabolic, cardiovascular, renal, liver, thyroid, gastrointestinal diseases
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Body Mass Index between 20 - 35 kg/m2
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Non-smoker
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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:
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Any medication likely to interfere with energy metabolism, appetite regulation and hormonal balance.
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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
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Physical activity of >=10 hours/week of moderate to vigorous physical activity
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Weight loss or gain of >=3 kg in the preceding 3 months
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Use of dietary supplements or unwilling to stop supplement use >= 2 weeks before enrolment and during intervention
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Pregnancy or lactation
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Intervention specific factors, including:
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Unable or unwilling to consume provided diets during the intervention
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Unsufficient storage space for provided diets
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Food sensitivities or vegetarian/vegan diet by choice
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Participation in another intervention study at the same time
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Living > 15 miles from the Imperial/NIHR Clinical Research Facility at Hammersmith Hospital
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No signed informed consent
Contacts and Locations
Locations
| Site | City | State | Country | Postal Code | |
|---|---|---|---|---|---|
| 1 | Cambridge Epidemiology & Trials Unit | Cambridge | United Kingdom | ||
| 2 | Imperial/NIHR Clinical Research Facility | London | United Kingdom | W12 0HS |
Sponsors and Collaborators
- University of Cambridge
- Imperial College London
Investigators
- Principal Investigator: Linda Oude Griep, PhD, MRC Epidemiology Unit, University of Cambridge
Study Documents (Full-Text)
More Information
Publications
None provided.- 17HH3878
- Research Ethics Committee