The statement, "Caffeine and Cardiovascular Disease," was published in the AHA's flagship peer-reviewed journal Circulation.

"Caffeine consumed in coffee is a key part of daily life for millions of people, and in our review of the most recent research, for most adults, intake of up to 400 mg of caffeine per day—roughly the equivalent of up to five cups of caffeinated coffee without added sugars or fillers—is safe and does not increase cardiovascular risk," said Gregory M. Marcus, professor of medicine at the University of California, San Francisco School of Medicine and chair of the volunteer writing group behind the scientific statement.

"However, high doses of caffeine, such as those found in energy drinks and energy shots, may have harmful effects on the heart and should be avoided," he added.

The authors noted that evaluating caffeine's effects on cardiovascular health is complex because coffee contains several bioactive compounds beyond caffeine. Some experimental studies suggest these compounds possess antioxidant and anti-inflammatory properties that may contribute to coffee's potential health benefits.

They also pointed out that additives such as milk, cream, flavoured syrups and sugar can influence coffee's overall health impact. Moreover, most existing studies are observational, meaning they can identify associations but cannot establish a direct cause-and-effect relationship.

Besides coffee, caffeine is also found in tea, chocolate, soft drinks, energy drinks, and certain over-the-counter and prescription medicines. The AHA said more research is needed to better understand how these different sources of caffeine affect cardiovascular health.

Key findings

Blood pressure: Research suggests caffeine affects blood pressure differently depending on the amount consumed. People with normal blood pressure who drank one to three cups of coffee daily showed a higher risk of developing hypertension, while those consuming more than three cups a day were found to have a lower risk. However, high-caffeine products such as energy drinks can significantly raise blood pressure, particularly among people with hypertension.

Type 2 diabetes: Drinking plain black caffeinated coffee regularly was associated with a lower risk of developing Type 2 diabetes, although researchers believe this benefit may stem from coffee's other bioactive compounds rather than caffeine itself.

Cholesterol: The statement found that cafestol, a natural compound present in both caffeinated and decaffeinated coffee, can increase levels of low-density lipoprotein (LDL), commonly known as "bad" cholesterol. Cafestol is abundant in unfiltered coffee, including espresso, French press, Turkish coffee and boiled coffee, but is largely absent in paper-filtered and instant coffee.

Heart rhythm: Recent studies found that consuming one to three cups of caffeinated coffee daily was not associated with an increased risk of atrial fibrillation, one of the most common heart rhythm disorders. However, the same level of coffee consumption may increase the occurrence of premature ventricular contractions (PVCs), or early heartbeats originating from the lower chambers of the heart. Very high caffeine intake from energy drinks has been linked to abnormal heart rhythms even in otherwise healthy young adults.

Heart disease and stroke: Drinking two to four cups of coffee per day was associated with a lower risk of coronary heart disease, heart failure and stroke. However, consuming more than four cups daily may increase the risk of heart failure.

Not all caffeine sources are equal

The AHA emphasised that different caffeinated products may have very different effects on health.

Although fewer studies have examined tea, existing evidence suggests it may also reduce the risk of atrial fibrillation, heart failure and stroke.

By contrast, energy drinks, caffeine gels, bars and supplements often contain additional ingredients that can accelerate caffeine absorption, amplify its effects, increase blood pressure and raise the risk of cardiovascular complications.

The statement called for more randomised clinical trials to better understand how different caffeinated beverages and products affect heart health and why individuals respond differently to caffeine.

The researchers also stressed the need for dedicated studies on energy drinks and other high-caffeine products, given their growing popularity.

Because of insufficient high-quality evidence, caffeine was not specifically included in the American Heart Association's 2026 Dietary Guidance to Improve Cardiovascular Health.

"Although research suggests caffeine consumption may be associated with certain cardiovascular benefits for some people, there is no one-size-fits-all strategy for safe caffeine consumption," Marcus said.

"People respond differently to caffeine depending on factors such as age, genetics, medications, underlying health conditions and how quickly their bodies metabolise it. What may be a reasonable amount for one person could cause heart palpitations, anxiety or sleep disruption in another. That's why it's important to pay attention to how your body responds and discuss your caffeine intake with your healthcare provider," he added.