Differential Effects of Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) on Platelet, Endothelial and Vascular Function

Study Overview
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Brief Summary
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The purpose of this study was to determine whether supplementation with oils enriched with long chain n-3 PUFA, either EPA or DHA, had a differential effect on platelet, endothelial and vascular function.

Detailed Description
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Relatively few studies have made a head-to-head comparison of DHA (22:6n-3) with EPA (20:5n-3). The understanding of this differential effect may be of great interest in populations with low EPA intake such as vegetarians, who may choose to supplement their dietary intake of long-chain n-3 PUFA in the form of DHA-rich algal oil. This study aimed to investigate the effect of supplementation with oils rich in either EPA or DHA (3g/day, 6 weeks) in healthy young males on platelet, endothelial and vascular function, as well as other CVD risk factors. The primary outcomes were platelet monocyte aggregates and endothelial progenitor cells - novel markers of platelet and endothelial function, measured by flow cytometry, Secondary outcomes included capillary density, measured by capillaroscopy to assess changes in microvascular function, pulse wave analysis, digital volume pulse and ambulatory blood pressure. Other secondary outcomes included lipid profiles (TAG, cholesterol, NEFA), glycaemic control (HOMA, QUICKI) and oxidative stress (isoprostane). The omega-3 index (erythrocyte EPA+DHA) was used as a marker of compliance.

Official Title
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Investigation Into Incorporation of (n-3) Polyunsaturated Fatty Acids Into Erythrocyte Membranes and Clearance, and Effects on Platelet Function, Arterial Function and Endothelial Repair

Conditions
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Healthy

Intervention / Treatment
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* Dietary Supplement: EPA-rich triacylglycerol oil
* Dietary Supplement: Placebo - olive oil (BP specification)
* Dietary Supplement: DHA-rich triacylglycerol oil


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy males No smokers Aged 18-45y old Able to understand the information sheet and comply with all the trial procedures Having given written consent to take part in the study prior to participation. Exclusion Criteria: Reported history of CVD (myocardial infarction, angina, venous thrombosis, stroke, dyslipidemia), diabetes (or fasting glucose ≥ 6.1 mmol/L), cancer, kidney, liver or bowel disease. Presence of gastrointestinal disorder or use of drug, which is likely to alter gastrointestinal motility or nutrient absorption. Current smokers; history of substance abuse or alcoholism (previous weekly alcohol intake >60 units/week); current self-reported weekly alcohol intake exceeding 28 units Recent use of hypolipidaemic, antihypertensive, antiplatelet or antithrombotic mediations Platelet count above or below the normal range or any history indicative of a congenital or acquired platelet or haemostatic defect. Allergy or intolerance to any component of study capsules Unwilling to restrict consumption of any source of fish oil for the length of the study Subjects reporting consumption of >1 portion oily fish per week Weight change of >3 kg in preceding 2 months; BMI <18 and >32 kg/m2 Blood pressure>160/90 mmHg Fasting blood cholesterol > 6.5 mmol/L; fasting triacylglycerol concentrations > 2.0 mmol/L

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Olive oil (BP specification)<br>5g per day | Dietary Supplement: Placebo - olive oil (BP specification)<br> <br> |
| Experimental: DHA-rich oil<br>Fish oil supplement (total = 5g/day) providing 3.1g/day of DHA triacylglycerol, blended with olive oil | Dietary Supplement: DHA-rich triacylglycerol oil<br> <br> |
| Experimental: EPA-rich oil<br>Fish oil supplement (total = 5g/day) providing 2.9g/day of EPA triacylglycerol, blended with olive oil | Dietary Supplement: EPA-rich triacylglycerol oil<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Platelet Monocyte Aggregates (PMA) | The endothelium plays a vital role in the regulation of blood flow, thrombosis and inflammation. Endothelium-derived anti-adhesive and anti-aggregant substances, including prostacyclin and nitric oxide, are known to inhibit platelet activation. Endothelial dysfunction or vessel wall injury lead to the activation of platelets, of which platelet-monocyte-aggregates (PMA) are a sensitive marker, and were shown to inversely correlate with markers of EF in patients with stable CHD. The measurement of PMA by flow cytometry is a method which reduces ex vivo platelet activation to its minimum and is believed to represent platelet activation in vivo. | 6 weeks | 
| Endothelial Progenitor Cell (EPC) counts | EPCs are a subgroup of circulating progenitor cells that are recruited from the bone marrow to repair the injured vasculature. They have been associated with a reduced CVD risk and may serve as markers of endothelial function because they represent a greater capacity for the endothelium to repair itself. Two populations of EPCs were measured by flow cytometry, described as 'early EPC' (KDR+/CD34+/CD133+) and 'late EPCs' (KDR+/CD34+/CD31+). | 6 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Capillary density | Capillary rarefaction has been associated to CVD risk factors such as hypertension, smoking and obesity. The cutaneous circulation has emerged as an accessible and representative vascular bed to look at microvascular dysfunction. Capillary density was measured by a Capiscope (kk technologies) | 6 weeks | 
| Arterial stiffness | Pulse wave analysis (PWA) was used to measure indices of arterial stiffness, including peripheral and central augmentation index, as well as central systolic and diastolic blood pressure. Digital volume pulse (DVP) was used to measure reflection and stiffness indices. | 6 weeks | 
| Blood Pressure (BP) and Heart Rate (HR) | Resting HR and BP were measured in the seated and supine position after 15 minute rest, on the days of both baseline and endpoint visits. In addition, ambulatory BP and HR (24h, daytime, nighttime) was measured 2-3 days prior to each visit. | 6 weeks | 
| Plasma isoprostane concentrations | 8-iso-prostaglandin-F2α (8-IsoP-F2α), a prostaglandin F2-like compound biosynthesized nonenzymatically by a free-radical oxygenation of arachidonic acid, was measured in plasma in order to assess oxidative stress. | 6 weeks | 
| Plasma Nitrate and Nitrites (NOx) concentrations | Plasma NOx was measured as a circulating marker of endothelial function. | 6 weeks | 
| Serum total cholesterol concentration |  | 6 weeks | 
| Serum Triacylglycerol concentrations |  | 6 weeks | 
| Serum high density lipoprotein concentration |  | 6 weeks | 
| Serum low density lipoprotein concentration |  | 6 weeks | 
| Serum non esterified fatty acids (NEFA) concentration |  | 6 weeks | 
| Serum Apolipoprotein B concentration |  | 6 weeks | 
| Plasma glucose concentration |  | 6 weeks | 
| Plasma insulin concentration |  | 6 weeks | 
| Serum adiponectin concentration |  | 6 weeks | 
| Serum resistin concentration |  | 6 weeks | 
| Erythrocyte phospholipid fatty acid profiles | The EPA and DHA content of erythrocyte lipids were used as a marker of compliance. | 6 weeks | 
| Fatty acid profile of plasma non esterified fatty acid fraction |  | 6 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Eicosapentaenoic acid, Docosahexaenoic acid, Cardiovascular risk, Platelet function, Endothelial function, Vascular function, young males