Moderate coffee consumption, up to about five 8-ounce cups of black coffee per day, is generally considered safe for most healthy adults and may even be associated with a reduced risk of heart disease, stroke, heart failure, and Type 2 diabetes, according to a new scientific statement from the American Heart Association. The findings were published in the journal Circulation.
The review highlighted that these potential benefits are most consistently observed with plain black coffee, rather than beverages laden with added sugars, flavored syrups, or heavy cream. These additions can negate the health advantages.
"For most healthy adults, up to about 400 milligrams of caffeine a day, which is roughly five cups of black coffee, appears safe," registered dietitian Lauren Manaker, who was not involved in the research, told Fox News Digital. "And the latest research links moderate coffee drinking with a lower risk of heart disease, stroke, heart failure and Type 2 diabetes. That's reassuring news for coffee lovers."
Manaker cautioned, however, that the composition of one's coffee is significant. "How you take your coffee makes a real difference," she stated. "The benefits show up most clearly with plain black coffee. Once you start piling on sugar, flavored syrups and cream, you may be trading away some of the good you were hoping to get."
The American Heart Association also differentiated coffee from energy drinks, noting that energy drinks often contain considerably higher caffeine levels and other stimulants. Higher caffeine intake, particularly from energy drinks and shots, has been linked to increased blood pressure and irregular heart rhythms.
"Coffee and energy drinks are not the same thing, and we shouldn't treat them that way," Manaker advised. "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. That's the source I'd steer people away from."
Researchers emphasized that individual responses to caffeine vary. Factors such as age, medication use, genetics, and the speed at which the body metabolizes caffeine can influence tolerance and potential risks. "There's no one-size-fits-all caffeine limit," Manaker said. "Your age, your medications, your genetics and how quickly your body clears caffeine all shape how you respond. What feels fine for your co-worker might leave you jittery or awake at 2 a.m."
Further research is recommended, as much of the current evidence is derived from observational studies. 
