American Heart Association: Up to five cups of coffee a day appears safe for most adults, but energy drinks may pose heart risks

Drinking moderate amounts of caffeinated coffee is safe for most adults and may even provide cardiovascular benefits, according to a new scientific statement from the American Heart Association (AHA). However, experts caution that high doses of caffeine—particularly those consumed through energy drinks and energy shots—may increase the risk of heart-related problems.

The statement, published in Circulation, reviews the latest evidence on caffeine consumption and cardiovascular health, including its effects on blood pressure, cholesterol, type 2 diabetes, heart disease, stroke, heart failure and cardiac arrhythmias.

According to the authors, most healthy adults can safely consume up to 400 mg of caffeine per day, which is roughly equivalent to three to five 8-ounce (240 ml) cups of regular black coffee without added sugar, syrups or cream.

Researchers found that moderate coffee consumption was associated with a lower risk of several cardiovascular and metabolic conditions, including type 2 diabetes, coronary heart disease, stroke, heart failure and atrial fibrillation. At the same time, randomized clinical trials suggest that caffeine may slightly increase the frequency of premature ventricular contractions (PVCs), although it does not appear to raise the overall risk of atrial fibrillation.

The authors emphasize that coffee contains numerous biologically active compounds in addition to caffeine. Some of these substances have antioxidant and anti-inflammatory properties, which may partly explain the health benefits observed in studies. Because of this, it remains difficult to determine how much of coffee's positive effects are due to caffeine alone.

Experts also note that adding sugar, flavored syrups, cream or milk may reduce coffee's potential health benefits, although more research is needed to confirm the impact of these ingredients.

The statement highlights that not all sources of caffeine affect the body in the same way. While coffee and tea have generally been associated with favorable cardiovascular outcomes, energy drinks often contain much higher concentrations of caffeine along with other stimulants that may enhance its effects. Energy shots, for example, may contain three to four times more caffeine per ounce than brewed coffee.

High caffeine intake from these products has been linked to elevated blood pressure and an increased risk of abnormal heart rhythms, even in otherwise healthy young adults.

The review also examined specific health outcomes. Drinking two to four cups of coffee per day was associated with a lower risk of coronary heart disease, heart failure and stroke, whereas consuming more than four cups daily may increase the risk of heart failure in some individuals.

Regarding blood pressure, studies produced mixed findings. People with normal blood pressure who consumed one to three cups of coffee per day had a slightly higher likelihood of developing hypertension in some studies, while those drinking more than three cups showed a lower risk. In contrast, large amounts of caffeine from energy drinks consistently raised blood pressure, particularly in people with existing hypertension.

Researchers also found that unfiltered coffee—such as espresso, French press, Turkish coffee and boiled coffee—contains cafestol, a natural compound that can increase LDL ("bad") cholesterol levels. Paper-filtered coffee and instant coffee contain little or no cafestol.

The authors stress that individual responses to caffeine vary considerably depending on genetics, age, metabolism, medications and underlying health conditions. Some people develop tolerance to caffeine, while others may experience palpitations, anxiety or sleep disturbances after relatively small amounts.

The AHA concludes that moderate coffee consumption appears safe for most adults, but there is no universal recommendation suitable for everyone. More randomized clinical trials are needed to better understand how different sources of caffeine influence cardiovascular health and to develop evidence-based recommendations for specific populations.

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