The American Heart Association (AHA) has released a new scientific statement 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 may even reduce the risk of cardiovascular disease. However, higher doses of caffeine, particularly from energy drinks and shots, can increase the risk of high blood pressure and irregular heart rhythms.
The statement, published in the AHA's flagship journal Circulation, reviews the latest research on caffeine and cardiovascular health. According to Gregory M. Marcus, M.D., M.A.S., FAHA, chair of the statement writing group and professor of medicine at the University of California, San Francisco, "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."
However, the statement warns that high doses of caffeine, such as those found in energy drinks and shots, can be harmful. Energy drink shots may contain 40-69 mg of caffeine per fluid ounce, three to four times more than regular coffee. These products have been linked to increased blood pressure and arrhythmias, especially in younger adults with low cardiovascular risk.
The statement highlights key findings from recent studies. Drinking two to four cups of caffeinated coffee per day was associated with a lower risk of heart disease, heart failure, and stroke. Black coffee without added sugars, flavors, or cream was linked to a reduced risk of type 2 diabetes, heart disease, stroke, heart failure, and some irregular heart rhythms. However, adding sugar, flavored syrups, milk, or cream likely reduces these benefits.
Regarding blood pressure, the effects of coffee vary. In people with optimal blood pressure, one to three cups per day was associated with an increased risk of developing high blood pressure, while more than three cups per day was linked to a lower risk. High doses of caffeine from energy drinks can significantly raise blood pressure, especially in those with existing hypertension.
The statement notes that coffee contains compounds other than caffeine, such as antioxidants and anti-inflammatory agents, which may contribute to its health benefits. However, separating the effects of caffeine from other coffee components is challenging. The writing group emphasizes the need for more research, particularly randomized controlled trials, to understand how different sources of caffeine affect cardiovascular health.
Individual responses to caffeine vary based on genetics, metabolism, age, and medication use. Marcus advises, "There is no 'one-size-fits-all' strategy for safe caffeine consumption. What may be a reasonable amount for one person could cause unwanted effects, such as heart palpitations, anxiety, or sleep disruption, in another." The statement was prepared on behalf of the AHA's Council on Lifestyle and Cardiometabolic Health, Council on Clinical Cardiology, and Stroke Council.
For more details, the full scientific statement is available online. Additional resources and multimedia can be found on the AHA's news release page.
