Rutin, a chemical present in apple, orange, onion and green and black tea, not only keeps blood clots at bay but can also be part of the treatment against heart attacks and strokes, a study says. Harvard researchers found that the compound helped block a potentially dangerous enzyme involved in the formation of blood clots. Called protein disulfide isomerase (PDI), the enzyme is released very quickly when blood clots form in the arteries and veins. Robert Flaumenhaft, professor at the Harvard Medical School, US, who led the study, said: “Rutin proved to be the most potently anti-thrombotic (clotting) compound that we ever tested in this model. “Clots occur in both arteries and in veins. Clots in arteries are platelet-rich, while those in veins are fibrin-rich. This discovery suggests that a single agent can treat and prevent both types of clots,” added Flaumenhaft, the Journal of Clinical Investigation reports. Researchers tested the ability of 500 different chemicals - including rutin - to block PDI using scientific models on computers. They found that rutin to be the most effective, which protected from blood clots that occur in arteries and veins, according to the Daily Mail. In future researchers hope to use rutin in treatments that could be used in patients at the risk of heart attacks and strokes.