American Heart Association says up to five cups of coffee a day are generally safe

The American Heart Association released a statement Monday indicating that most adults can safely drink up to five cups of coffee a day, roughly 400 milligrams of caffeine. The review, published in the association’s journal Circulation, suggests that this level of caffeine from plain brewed coffee may be linked to a reduced risk of several cardiovascular conditions, including type 2 diabetes, heart disease, stroke, heart failure and certain arrhythmias.

"Caffeine and Cardiovascular Disease" focuses on coffee without added sweeteners, dairy or flavorings, noting that an 8-ounce cup typically contains 75 to 160 mg of caffeine.

The statement also highlights a lower risk of atrial fibrillation but a higher risk of premature ventricular contractions associated with coffee consumption. It acknowledges that research on caffeine’s effects is complicated by the difficulty of isolating caffeine from other coffee compounds and that most studies are observational, limiting causal conclusions.

The authors call for additional research to clarify caffeine’s impact from coffee and other sources. In contrast, the paper warns that energy drinks, which often contain 40 to 69 mg of caffeine per fluid ounce, are associated with increased risk of high blood pressure and irregular heart rhythms.