Traditionally, coffee is seen as a dangerous substance that may increase high blood pressure, and strokes.
More evidence was found during a study of older men with high blood pressure. Researchers found that the incidence of thromboembolic stroke was higher in men who drank 3 or more cups of coffee per day. Other kinds of strokes (such as hemorrhagic stroke) were not effected by coffee consumption.


The study was published in the Journal of Clinical Epidemiology and included 500 men, aged 55-68.

Though coffee alone may increase one's likelihood of having a stroke, a new treatment is being developed that combines caffeine and alcohol. Not what most people would consider a healthy combination, but caffeinol has been shown to limit the damage caused by ischaemic strokes (in lab animals). The basic idea behind the drug, is that it improved blood flow to the brain.

And as usual, tea has been shown to be a helpful substance. Another study of 550 men (in the Archives of Internal Medicine) revealed that drinking almost 5 cups of tea per day, reduced the likelihood of stroke by 69 percent. Flavonoids and antioxidants are thought to be the beneficial components here. Foods that are high in flavonoids may also help prevent strokes.

References
Coffee Cocktail Limits Stroke Damage
Coffee Linked to Stroke Risk
Drinking Black Tea May Cut Risk of Stroke