Yes, most adults can get up to 400 mg of caffeine per day from coffee – but not more – according to the American Heart Association. Measured in individual drinks, that’s around five 8-ounce cups of joe per day.
This amount of black coffee might not only be safe, it could be “linked to cardiovascular health benefits in some individuals,” said the AHA. It also said consuming black coffee without sugars, flavors, milk or cream was linked to a lower risk of Type 2 diabetes, heart disease, stroke, heart failure and some irregular heart rhythms.
For example, the association noted “research suggests that caffeinated coffee may reduce insulin sensitivity in the short term,” and that drinking black coffee regularly has been linked to a lower risk of developing Type 2 diabetes. However, the AHA stresses that the benefit is only associated with coffee, not other sources of caffeine.
“This benefit may be due to compounds in coffee other than caffeine,” the association said. “More research is needed to clarify the impact on Type 2 diabetes of caffeinated coffee vs. various compounds in coffee.”
Many people rely on a cup of coffee to get them going in the morning. When the caffeine in coffee is metabolized by the liver, it generally reaches peak concentration for most people within an hour, according to the AHA. Short term effects include temporary increases in blood pressure, heart rate, blood sugar and alertness. That last one is why it’s a go-to wake-up beverage and aid for nights of all-night studying.
Reactions to caffeine can vary from person to person and they can depend on tolerance levels. Some people may experience heart palpitations and/or sleep disruption from caffeine and some people might need to consume more over time to get the alertness side effect.
Drinking coffee is the most common way that people consume caffeine (the world’s most popular stimulant and psychoactive substance, based on previous studies) but it’s not the only way. Energy drinks from Red Bull to Celsius have grown in popularity in recent years (some containing more than 200 mg of caffeine in a single can) and there’s also tea, chocolate, some soft drinks and even medications that contain caffeine.
“Higher doses of caffeine, such as levels found in energy drinks including energy shots, may cause cardiovascular harm, according to a new American Heart Association scientific statement, ‘Caffeine and Cardiovascular Disease,’ published today in the American Heart Association’s flagship peer-reviewed scientific journal Circulation,” said the AHA Monday.
Audacy has previously reported on lawmakers’ efforts to investigate energy drinks and on deaths associated with highly caffeinated ice tea drinks sold at the chain restaurant Panera. In 2024, we reported on research that indicated drinking more than 400 mg of caffeine daily could increase susceptibility to cardiovascular disease.
Why does the research on coffee in particular indicate a potential benefit in this area rather than increased risk? Well, the AHA said that some “experimental studies suggest that the bioactive compounds in coffee may have antioxidant and anti-inflammatory properties, which may help explain some health benefits.”
Authors of the recent statement noted that studying the effects of caffeine on the cardiovascular system in particular can be challenging. They said more research is needed about caffeine from sources other than coffee to understand its impact in this area, though tea has also been associated with positive health effects similar to coffee.
Additionally, they warned that adding sugar, flavored syrups, milk and cream to coffee may disrupt its potential health benefits. Audacy has also reported on research that indicates the type of cup coffee comes in can impact how healthy it is.
“Higher caffeine intake, such as levels found in energy drinks including energy shots, was associated with cardiovascular harm, such as increased risk of high blood pressure and irregular heart rhythm. Energy drink shots may contain 40-69 mg of caffeine per fluid ounce, three to four times more caffeine than regular caffeinated coffee,” said the AHA.
