Dietary Intervention and Vascular Function

Study Overview
=================
Brief Summary
-----------------
It is well established that diet plays an important role in both the development and progression of heart disease. Different types of dietary fat have varying effects on heart disease risk factors. The elasticity of an individual's blood vessels is strongly associated with heart disease risk and recent evidence suggests that dietary manipulation may influence elasticity of the blood vessels with dietary fat (including saturated, monounsaturated and polyunsaturated fatty acids) as a potentially important modulator. Substantial evidence exists on the effects of monounsaturated fats (type of fatty acids mainly found in olive and rapeseed oil), n-6 polyunsaturated fats (type of polyunsaturated fatty acids found in vegetable oils) and saturated fat (found mainly in animal derived products) on lipid levels. However, the influence of these dietary fats on the elasticity of blood vessels remains unclear.The main purpose of the DIVAS study is to determine the effects of the substitution of saturated fats with either n-6 polyunsaturated or monounsaturated fats on blood vessel elasticity and to determine the effects of these different dietary fats on other risk factors for heart disease including lipoproteins and inflammatory biomarkers.

Official Title
-----------------
The Effects of the Substitution of Dietary SFA With n-6 PUFA or MUFA on Vascular Function

Conditions
-----------------
Cardiovascular Disease

Intervention / Treatment
-----------------
* Dietary Supplement: SFA diet
* Dietary Supplement: MUFA diet
* Dietary Supplement: n-6 PUFA diet


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Adults should have a relative risk (RR) of > 1.5 of developing cardiovascular disease (CVD) based on presenting with at least one recognised risk factor for CVD: total cholesterol (TC) > 6.0 mmol/l HDL cholesterol (HDLC) ≤ 1.0 mmol/l male, ≤ 1.3 mmol/l female Glucose ≥ 6 mmol/l Stage 1 hypertension or above i.e. a systolic BP ≥ 140 mmHg, diastolic BP ≥ 90 mmHg BMI 28-35 kg/m2 waist >102 cm male or > 84 cm female Adults with a first degree relative with either a history of premature CVD - age of onset younger than 55 y in fathers, sons or brothers or younger than 65 y in mothers, daughters or sisters, or type 2 diabetes. Exclusion Criteria: having suffered a myocardial infarction/stroke in the past 12 months diabetic (diagnosed or fasting glucose > 7 mmol/l) or suffer from other endocrine disorders suffering from renal or bowel disease or have a history of choleostatic liver or pancreatitis on drug treatment for hyperlipidaemia, hypertension, inflammation or hypercoagulation no history of alcohol abuse planning or on a weight reducing regime taking any fish oil, fatty acid or vitamin and mineral supplements pregnant, lactating or planning a pregnancy smokers

Ages Eligible for Study
-----------------
Minimum Age: 21 Years
Maximum Age: 60 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: high saturated fat diet<br> | Dietary Supplement: SFA diet<br>* Volunteers are following a high saturated fat diet for a 4-month period<br>|
| Experimental: high monounsaturated fat diet<br> | Dietary Supplement: MUFA diet<br>* Volunteers are following a high monounsaturated fat diet for a 4-month period<br>|
| Experimental: high n-6 polyunsaturated fat diet<br> | Dietary Supplement: n-6 PUFA diet<br>* Volunteers are following a high n-6 polyunsaturated fat diet for a 4-month period<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percent Change in Flow Mediated Dilatation (FMD) |  | Baseline, 4 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cardiovascular Risk Factors (Lipids, Inflammatory Markers, Indices of Insulin Resistance, Cell Microparticles, Endothelial Progenitor Cells) | Data for fasting serum lipids (total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), TC:HDL-C ratio, low-density lipoprotein cholesterol (LDL-C), triacylglycerol (TAG)). | 4 months | 
| 24-hour Ambulatory Blood Pressure | 24-hour, daytime and night-time measures of systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP; SBP-DBP) and heart rate (HR) | 4 months | 
| Vascular Stiffness by Pulse Wave Velocity (PWV), Pulse Wave Analysis (PWA) and Digital Volume Pulse (DVP) | PWV (m/s) PWA produces Augmentation Index (AIx; %) DVP produces Stiffness Index (SI; m/s) and Reflection Index (RI; %) | 4 months | 
| Microvascular Reactivity (Laser Doppler Imaging With Iontophoresis) | Laser Doppler imaging (LDI) with iontophoresis of acetylcholine (Ach; endothelium-dependent vasodilation) and sodium nitroprusside (SNP; endothelium-independent vasodilation). | 4 months | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
fatty acids, cardiovascular disease, vascular function, microparticles