Most adults can safely drink five cups of coffee a day, according to the American Heart Association.
The organization said in a July 20 statement that synthesizes research on caffeine that the latest studies indicate that for most adults, consuming up to 400 milligrams of caffeine a day—or up to five 8-ounce cups of coffee—without added sugar and milk is not only safe, but appears to result in a lower risk of cardiovascular disease.
Higher levels of caffeine, such as those found in energy drinks, may harm the heart and blood vessels, the association said.
Most of the studies underpinning the guidance come from observational research, although there are a growing number of randomized, controlled trials that examined the relationship between caffeine and various health problems, including a trial that found no impact on glucose levels….