The American Heart Association (AHA) has released a new scientific statement on caffeine and cardiovascular health, concluding that for most adults, consuming up to 400 mg of caffeine per day—equivalent to about five 8-ounce cups of caffeinated coffee—is safe and linked to a lower risk of several cardiovascular conditions, including heart failure, heart disease, and stroke. However, higher doses, particularly those found in energy drinks and energy shots, may increase risks of high blood pressure and irregular heart rhythms.
Published in the AHA's flagship journal Circulation, the statement reviews recent research on caffeine's effects on high blood pressure, cholesterol, Type 2 diabetes, coronary heart disease, stroke, heart failure, atrial fibrillation, and other arrhythmias. According to Gregory M. Marcus, M.D., M.A.S., FAHA, chair of the statement's writing group and professor of medicine at the University of California, San Francisco, “for most adults, intake of up to 400 mg of caffeine/day ... is safe and does not increase cardiovascular risk.” However, he cautioned that “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 notes that studying caffeine is challenging because coffee contains other bioactive compounds with antioxidant and anti-inflammatory properties that may contribute to health benefits. Most studies are observational, so they cannot prove cause and effect. Additionally, additives like sugar, cream, and flavored syrups likely reduce potential benefits. The AHA emphasizes that people respond differently to caffeine based on genetics, metabolism, age, and underlying health conditions.
Key findings include that 1–3 cups of caffeinated coffee per day did not increase atrial fibrillation risk but may increase premature ventricular contractions. Higher intakes (2–4 cups daily) were linked to lower risks of heart disease, heart failure, and stroke, though more than 4 cups may increase heart failure risk. Unfiltered coffee (espresso, French press) contains cafestol, which can raise LDL (“bad”) cholesterol, whereas paper-filtered or instant coffee does not. Energy drinks, with caffeine concentrations 3–4 times higher than coffee, were associated with increased blood pressure and arrhythmias, particularly in younger, healthy adults.
The AHA calls for more research on different caffeine sources and individual variability. The statement did not set formal recommendations for caffeine intake, noting insufficient rigorous data. Instead, it advises individuals to monitor their own responses and discuss caffeine use with healthcare providers. The full statement is available online at https://www.ahajournals.org/doi/10.1161/CIR.000000000000XXXX.
