New research published today in the American Heart Association's flagship journal, Circulation, supports that consuming up to 400 mg of caffeine per day—equivalent to about 5 cups of brewed coffee—is safe for most adults and may reduce the risk of several cardiovascular conditions, including heart failure, heart disease, and stroke. However, the scientific statement warns that higher doses, particularly those found in energy drinks and shots, can increase the risk of high blood pressure and irregular heart rhythms.
The statement, titled "Caffeine and Cardiovascular Disease," was prepared by a volunteer writing group and reviews the latest evidence on caffeine's cardiovascular effects. "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/day, the equivalent of up to 5 cups of caffeinated coffee per day without added sugars or fillers, is safe and does not increase cardiovascular risk," said chair Gregory M. Marcus, M.D., M.A.S., FAHA, professor of medicine at the University of California, San Francisco. "However, high doses of caffeine, such as those found in energy drinks including energy shots, may have harmful effects on the heart and should be avoided."
The statement highlights that coffee contains bioactive compounds with antioxidant and anti-inflammatory properties, which may partly explain its health benefits. Observational studies link moderate coffee consumption to lower risks of Type 2 diabetes, heart disease, stroke, and heart failure. Yet the authors caution that most studies are observational and cannot prove causation. Adding sugar, cream, or flavored syrups likely diminishes these benefits.
Specific findings include that 1-3 cups of coffee daily may increase the risk of high blood pressure in some, but more than 3 cups was associated with lower risk. Caffeinated coffee may reduce insulin sensitivity short-term but is linked to lower Type 2 diabetes risk long-term. Unfiltered coffee (espresso, French press) contains cafestol, which can raise LDL cholesterol, while filtered coffee does not. For heart rhythm, 1-3 cups daily did not increase atrial fibrillation risk but may increase premature ventricular contractions. Very high caffeine doses from energy drinks have triggered arrhythmias in healthy young adults.
The statement emphasizes individual variability in caffeine metabolism due to genetics, age, and medications. "There is no 'one-size-fits-all' strategy for safe caffeine consumption," Marcus said. The AHA's 2026 Dietary Guidance did not include caffeine due to insufficient data for recommendations. The writing group calls for more randomized controlled trials, especially on energy drinks and other caffeinated products, to better understand their cardiovascular impact.
For more details, the full manuscript is available online at https://www.ahajournals.org/doi/10.1161/CIR.0000000000001234.
