The American Heart Association (AHA) has concluded that consuming up to 400 milligrams of caffeine a day — roughly the equivalent of five 8-ounce cups of black coffee — is generally safe for most healthy adults and is not associated with a higher risk of heart disease. The finding, published in the journal Circulation, draws on a review of existing evidence on caffeine and cardiovascular health and is likely to reassure millions of regular coffee drinkers, though the AHA stressed that the research does not amount to a recommendation that people should begin drinking five cups a day.

According to the statement, moderate consumption of caffeinated coffee was linked to a lower risk of coronary artery disease, stroke and heart failure, as well as a possible reduced risk of type 2 diabetes. However, the AHA cautioned that the evidence is strongest for plain black coffee, not for drinks loaded with sugar, syrups or cream. “How you take your coffee makes a real difference,” Lauren Manaker, a registered dietitian who was not involved in the research, told Fox News Digital. “The benefits show up most clearly with plain black coffee. Once you start piling on sugar, flavoured syrups and cream, you may be trading away some of the good you were hoping to get.”

The AHA drew a sharp distinction between ordinary brewed coffee and products containing concentrated or very high doses of caffeine. Evidence from normal coffee consumption, the statement said, should not be applied to energy drinks, caffeine shots or purified caffeine products, which have been associated with concerns including abnormal heart rhythms and elevated blood pressure. Manaker noted that energy drinks and shots “can pack three to four times the caffeine of regular coffee, often with added ingredients, and higher doses have been linked to raised blood pressure and irregular heart rhythms.”

Researchers also found that individual responses to caffeine vary widely. Factors including genetics, age, habitual consumption, medications and how quickly the body metabolises caffeine can all influence tolerance and risk. The AHA has called for more randomised controlled trials to better understand the direct effects of caffeine on cardiovascular health, noting that much of the current evidence comes from observational studies. The US Food and Drug Administration has previously stated that up to 400 mg of caffeine a day is not generally associated with dangerous negative effects for most healthy adults. For now, the central message from the AHA review is one of moderation: up to 400 mg of caffeine a day is considered safe for most adults, but the figure is an approximate upper limit, not a target.