Drinking Coffee or Tea had a Lower Incidence of Stroke and Dementia

People who drank coffee, tea, or a combination of the two had a lower risk of stroke and dementia, and the risk was reduced the most for those who drank two to three cups of coffee or three to five cups of tea per day, according to results published today in the journal PLOS Medicine.

To examine how coffee or tea may impact the risk of stroke and dementia, investigators studied 365,682 participants between ages 50 and 74 from the UK health resource with the following results:

People who drank two to three cups of coffee, or three to five cups of tea per day, or a combination of four to six cups of coffee and tea had the lowest incidence of stroke or dementia.

Two to three cups of coffee with two to three cups of tea daily was associated with a 32 percent lower risk of stroke and a 28 percent lower risk of dementia compared with people who drank neither coffee nor tea.

Coffee alone or in combination with tea was associated with lower risk of post-stroke dementia. Post-stroke dementia is a condition where symptoms of dementia occur after a stroke.

Although coffee and tea consumption were associated with a lower incidence of dementia, stroke, and post-stroke dementia, the study was not set up to prove causality. However, the association is believable, says Douglas Scharre, MD, a professor of clinical neurology and psychiatry and the director of cognitive neurology at the Ohio State University Wexner Medical Center in Columbus. “Several studies have found an association between caffeine consumption and decreased risk of stroke, dementia, Alzheimer's disease, and Parkinson's disease,” he says.

One possible explanation could be related to caffeine’s stimulating effect on the brain, which in turn impacts our mood and makes us more alert, says Dr. Scharre. “Stroke and dementia are both brain disorders; increased brain excitability may impact brain reserve and delay dementia,” he says. 

Previous studies have shown that coffee was associated with a decreased risk of heart failure, according to the American Heart Association (AHA). There is evidence that heart failure is associated with an increased short-term and long-term risk of stroke.

Drinking up to 400 milligrams (mg) of caffeine a day is not associated with negative or dangerous health effects, according to the U.S. Food and Drug Administration (FDA). The average cup of green or black tea has 30 to 50 mg of caffeine, and an 8 ounce cup of coffee has about 80 to 100 mg. 

But too many cups of coffee or tea can cause insomnia, jitters, anxiousness, and an upset stomach. And the recommendations for coffee are for black coffee as many coffee-based drinks have a lot of added fats and sugar and are high in calories.