Platelet activation and aggregation play an integral role in hemostasis and thrombosis. Overactivation can lead to the formation of large thrombi and the blockage of essential blood vessels. Certain micronutrients are able to actively intervene in the biochemical clotting cascade, including the marine omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and water-soluble tomato concentrate, and may therefore be beneficial to cardiovascular health.
Cardiovascular disease is the leading cause of death worldwide. Platelet activation and aggregation play an integral role in hemostasis and thrombosis. Platelets are lens-shaped structures measuring 2–3 µm in diameter that do not have a nucleus and are formed from fragments of cytoplasm derived from the megakaryocytes of bone marrow. Platelet aggregation is a key process in blood clotting. However, excess aggregation can result in the formation of thrombi, which in turn can block the blood vessels and lead to necrosis of local tissues. Platelet hyperactivity can compromise circulation, accelerate atherosclerotic plaque development, and further increase the risk of cardiovascular disease (CVD).
It is currently thought that diets and nutrients may play a role in preventing and/or ameliorating cardiovascular disease (CVD), particularly due to their effects on platelet function. Diets such as the Mediterranean diet and vegetarian diet have inverse relationships with incidence of CVD. Dark chocolate, garlic, ginger, marine omega-3 fatty acids, onion, purple grape juice, tomatoes, and wine all reduce platelet aggregation (1).
Damage to the endothelium of the blood vessels leads to the exposure of collagen. Platelets will stick to the collagen and then become activated, releasing thromboxane A2 (TX A2), an eicosanoid derived from membrane arachidonic acid, which in turn attracts more platelets. Subsequently, fibrous strands of a protein called fibrin develop on top of those platelets. A thrombus (clot) is formed when red blood cells become trapped within fibrin mesh and are then themselves covered in further fibers. This process repeats itself many times, causing a thrombus to form (2).
The first stage in platelet aggregation is a change in the shape of the platelets, which allows them to become sticky and adhere to one another. Second, the platelets express proteins on their cell surface such as P-selectin, which enable the platelets to stick to the blood vessel, and G proteins, which allow the platelets to bind fibrin.
Thromboxane A2 (TXA2) is a product of arachidonic acid (ARA) created through the actions of the enzyme cyclooxygenase (COX). Subsequently, TXA2 mediates the production of ADP and collagen – these molecules further amplify the platelet aggregation process. In addition, TXA2 also stimulates the production of thrombospondin, which is converted to thrombin. Thrombin then converts fibrinogen into fibrin. Clotting factors, including vitamin K-dependent clotting factors, play a role in both of these latter two stages.
Water-soluble tomato concentrate (WTSC) affects platelet aggregation by decreasing the expression of P-selectin and GPIIb/IIIa and the production of TXA2, and inhibiting ADP- and collagen-mediated platelet aggregation. Importantly, these actions are reversible (please see the diagram for further clarity).