Cardiovascular disease is a major cause of mortality worldwide resulting in one out of three global deaths. One of the main characteristics of cardiovascular disease is impaired blood flow and increased formation of clots. Platelets are clot-forming cells responsible for prevention of bleeding. However, in disease state they may be overly activated and tend to stick to each other, promoting blood clots and blockage of vessels.

Conjugated linoleic acids (CLA) are unique fatty acids present in dairy food products and beef which would help to prevent platelets from clotting and thus help to prevent cardiovascular disease. However, the mechanisms by which those fatty acids affect platelet function are not yet fully understood. We designed a human intervention study assessing the mechanisms by which CLA beneficially affect platelet function and markers of haemostasis and inflammation in humans.

Despite being trans fatty acids, dietary conjugated linoleic acids( CLA) have been associated with decreased atherogenesis, beneficial effects on insulin sensitivity , glucose and lipid profile and body composition in animal studies.Todate only few studies have studied the effects of the two individual CLA isomers on body composition , lipoprotein metabolism immune function , inflammation , insulin sensitivity and oxidative stress in humans.

A previous study revealed that both cis9,trans11 and trans10,cis12 CLA, as well as CLA mix, significantly decreased agonist-induced platelet aggregation and TxB2 production ex vivo compared with linoleic acid. No effect on agonist-induced platelet aggregation or other blood clotting parameters in healthy female volunteers was observed upon supplementation with 3.9 g/d CLA, compared with sunflower oil, but this may have been due to the low number of subjects participating in this study.

Indeed, supplementation with 13.0 g/day of CLA mix - 50:50 blend, compared with placebo oil, significantly decreased fibrinogen levels in type 2 diabetes patients, and fibrinogen and plasminogen activator inhibitor-1 levels were significantly lower upon intervention with CLA milk (4.7 g/d cis9,trans11 CLA and 0.4 g/d trans10,cis12 CLA), compared with CLA mix (2.3 g/d cis9,trans11 CLA and 2.2 g/d trans10,cis12 CLA), and lower compared with olive oil, in postmenopausal women.Thus overall evidence indicates that especially the cis9,trans11 CLA isomer may prevent platelet activation and aggregation, and possibly display anticoagulant properties. However, so far this has not been assessed in detail.

In this study we assess effects of supplementation of cis9,trans11 CLA-rich oil on platelet function by measuring not only platelet aggregation but also in vitro coagulation and platelet activation in healthy overweight humans. In addition, we examine the effects of CLA supplementation on plasma and cellular marker of inflammation and oxidative stress.

Inclusion Criteria:• Healthy men and women aged 35-74 years

• blood pressure below 160/90 mmHg;
• fasting plasma glucose < 7 mmol/L;
• total cholesterol < 8 mmol/L,with cholesterol/HDL ratio < 6 and/or ASSIGN score < 20%)
• platelet count > 170x109/L
• haematocrit above 40 % for males and above 35 % for females
• haemoglobin above 130 g/L for males and above 115 g/L for females
• having a 10-20% risk for developing cardiovascular disease within the next 10 years based on the ASSIGN calculation (http://cvrisk.mvm.ed.ac.uk/index.htm) including the following factors: age, gender, number of cigarettes smoked per day, Scottish Index of Multiple Deprivation (SIMD)/postcode, systolic blood pressure, levels of total and HDL cholesterol and family history of cardiovascular disease or having at least one additional risk factor such as being over 50 years old, BMI above 25 kg/m2, elevated triglyceride levels (> 1.7 mmol/L) or elevated glucose levels (> 5.6 mmol/L);

Exclusion Criteria:Exclusion criteria Subjects are excluded if

• They are regularly taking aspirin or aspirin-containing drugs, or other anti-inflammatory drugs;
• They are taking drugs or herbal medicines known to alter platelet function or the haemostatic system in general;
• They are diagnosed with diabetes, hypertension, renal, hepatic, haematological disease or coronary heart disease;
• They are undertaking more than 6 hours vigorous exercise per week
• They are pregnant (or planning to become pregnant) or lactating;
• They have given a pint of blood for transfusion purposes within the last month;
• They have unsuitable veins for blood sampling;
• They are inability to understand the participant information sheet or inability to speak, read and understand the English language.