Dietary Intervention and Vascular Function (DIVAS)

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

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.

Study Overview

• Status: Completed
• Conditions: Cardiovascular Disease
• Intervention / Treatment: Dietary supplement: SFA diet; Dietary supplement: MUFA diet; Dietary supplement: n-6 PUFA diet

• Study Type: Interventional
• Enrollment (Actual): 202
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Berkshire
    • Reading, Berkshire, United Kingdom, RG6 6AP
      • Department of Food and Nutritional Sciences, University of Reading
    • Reading, Berkshire, United Kingdom, RG6 6AP
      • University of Reading

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 21 years to 60 years (ADULT)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: PREVENTION
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: SINGLE

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
ACTIVE_COMPARATOR: high saturated fat diet	Dietary supplement: SFA diet; Volunteers are following a high saturated fat diet for a 4-month period
EXPERIMENTAL: high monounsaturated fat diet	Dietary supplement: MUFA diet; Volunteers are following a high monounsaturated fat diet for a 4-month period
EXPERIMENTAL: high n-6 polyunsaturated fat diet	Dietary supplement: n-6 PUFA diet; Volunteers are following a high n-6 polyunsaturated fat diet for a 4-month period

What is the study measuring?

Primary Outcome Measures

Outcome Measure	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

Collaborators and Investigators

• Sponsor: University of Reading

Publications and helpful links

General Publications

• Weech M, Altowaijri H, Mayneris-Perxachs J, Vafeiadou K, Madden J, Todd S, Jackson KG, Lovegrove JA, Yaqoob P. Replacement of dietary saturated fat with unsaturated fats increases numbers of circulating endothelial progenitor cells and decreases numbers of microparticles: findings from the randomized, controlled Dietary Intervention and VAScular function (DIVAS) study. Am J Clin Nutr. 2018 Jun 1;107(6):876-882. doi: 10.1093/ajcn/nqy018.
• Shatwan IM, Weech M, Jackson KG, Lovegrove JA, Vimaleswaran KS. Apolipoprotein E gene polymorphism modifies fasting total cholesterol concentrations in response to replacement of dietary saturated with monounsaturated fatty acids in adults at moderate cardiovascular disease risk. Lipids Health Dis. 2017 Nov 23;16(1):222. doi: 10.1186/s12944-017-0606-3.
• Vafeiadou K, Weech M, Altowaijri H, Todd S, Yaqoob P, Jackson KG, Lovegrove JA. Replacement of saturated with unsaturated fats had no impact on vascular function but beneficial effects on lipid biomarkers, E-selectin, and blood pressure: results from the randomized, controlled Dietary Intervention and VAScular function (DIVAS) study. Am J Clin Nutr. 2015 Jul;102(1):40-8. doi: 10.3945/ajcn.114.097089. Epub 2015 May 27.
• Weech M, Vafeiadou K, Hasaj M, Todd S, Yaqoob P, Jackson KG, Lovegrove JA. Development of a food-exchange model to replace saturated fat with MUFAs and n-6 PUFAs in adults at moderate cardiovascular risk. J Nutr. 2014 Jun;144(6):846-55. doi: 10.3945/jn.114.190645. Epub 2014 Apr 9.

Study record dates

Study Major Dates

• Study Start: May 1, 2010
• Primary Completion (ACTUAL): October 1, 2012
• Study Completion (ACTUAL): October 1, 2012

Study Registration Dates

• First Submitted: November 16, 2011
• First Submitted That Met QC Criteria: November 21, 2011
• First Posted (ESTIMATE): November 23, 2011

Study Record Updates

• Last Update Posted (ESTIMATE): July 15, 2014
• Last Update Submitted That Met QC Criteria: June 12, 2014
• Last Verified: June 1, 2014

More Information

Terms related to this study

• Keywords: cardiovascular disease; vascular function; microparticles; fatty acids
• Additional Relevant MeSH Terms: Cardiovascular Diseases
• Other Study ID Numbers: N02044