Since someone, either in my office or by e-mail, asks me this question at least once a week, this might be a good opportunity to put the matter to rest.
Or maybe not.
Physicians, especially cardiologists, have been recommending daily aspirin to their patients for decades. The theory rested on the phenomenon that aspirin ever so slightly interfered with blood clot formation, and that small blood clots were responsible for heart attacks and strokes. You didn’t need to take much: a low-dose aspirin (81 mg–formerly called baby aspirin) would do just fine.