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

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

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.

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.

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