Guarana
A university study in Brazil of guaraná extract showed a platelet aggregation decrease of up to 37% of control values and a decrease of platelet thromboxane formation from arachidonic acid of up to 78% of control values. This study may be significant to stroke and heart attack risk reduction because when excess thromboxane formation occurs, an arterial blood clot can develop, resulting in a heart attack or ischemic stroke.