The American Heart Association published a scientific statement titled "Caffeine and Cardiovascular Disease" in the journal Circulation. The document summarizes current evidence regarding caffeine consumption and its relationship to cardiovascular health.

Gregory Marcus, MD, MAS, of the University of California San Francisco, served as chair of the scientific statement volunteer writing group. He outlined the organization's position on safe intake levels and potential health outcomes.

"The convergence of evidence from large cohort studies and small randomized controlled trials supports the conclusion that moderate caffeine or coffee consumption (up to 400 mg/d caffeine or ≈3 to 5 cups of coffee at 8 oz per cup) is safe for most adults and is associated with lower risk of cardiovascular disease, including coronary heart disease, stroke, heart failure, and AF [atrial fibrillation], as well as hypertension and type 2 diabetes," Marcus said.

Consuming up to 400 mg of caffeine per day, equivalent to 3 to 5 eight-ounce cups of coffee, is considered safe for most adults. Large prospective cohort studies showed modest inverse associations between habitual coffee consumption and all-cause mortality across diverse populations. The lowest mortality risk was observed at 2 to 4 cups of coffee daily, whether caffeinated or decaffeinated.

Habitual coffee consumption is associated with a lower risk of incident type 2 diabetes in observational cohort studies. This consumption was associated with a 20% to 30% lower risk of developing type 2 diabetes. Around 1.5 to 3.5 cups a day of coffee consumption was associated with an approximately 10% lower coronary artery disease risk.

The lowest heart failure risk has been reported at roughly 4 cups of coffee per day. Caffeinated coffee consumed at around 1 to 3 cups per day decreases the risk of atrial fibrillation occurrence. Daily coffee consumption can cut the risk of atrial fibrillation returning by 39% for patients who have had a procedure to address an irregular heart rhythm.

Caffeinated coffee consumption increases the frequency of premature ventricular contractions. Unfiltered coffee, such as French press, Greek/Turkish, and Scandinavian boiled coffee, raised LDL cholesterol based on controlled trials. Unfiltered coffee options, including espresso, retain a natural compound called cafestol that raises low-density lipoprotein cholesterol.

High caffeine doses, such as those in energy drinks, should be avoided. Energy drink shots may contain 40-69 mg of caffeine per fluid ounce, which is 3-4 times more caffeine than regular caffeinated coffee. Harm was more likely when coffee and caffeinated products were combined with sugar, flavored syrups, and dairy products.

Jennifer Miao, board-certified cardiologist and medical unit fellow, addressed the distinction between different caffeine sources. "The AHA distinguishes between coffee and energy drinks, which can pose significant cardiovascular harm," Miao said.

"Consume caffeine in moderation, not solely for potential health benefits," Miao said. Marcus added that individual responses to caffeine vary.

"Although research suggests that caffeine consumption may be associated with certain cardiovascular benefits for some people, it's important to remember that there is no 'one-size-fits-all' strategy for safe caffeine consumption," he said.

"People can respond very differently to caffeine based on various factors, such as age, medications, underlying health conditions, genetics, and how quickly their bodies metabolize it," he said. These metabolic rates are influenced by inherited variations in the liver enzyme gene CYP1A2, which dictate how fast an individual's body metabolizes stimulants. Caffeine consumed in coffee is metabolized by the liver and generally reaches peak concentration for most people within an hour.

A regular brewed, non-specialty, caffeinated coffee typically contains 9.4-20.6 mg of caffeine per fluid ounce. Coffee has been linked to supposed benefits in cancer, liver health, and mental disorders, though not conclusively. He noted the complexity of the data surrounding blood pressure.

"Coffee is potentially linked to lower risks of type 2 diabetes, stroke, and heart failure, though its relationship with blood pressure is complex and data isn't entirely consistent across the board," he said. Priorities for future research include more randomized studies such as crossover and pragmatic trials.

Cardiovascular Disease remains the leading cause of death globally, with an estimated 17.9 million deaths annually, according to the World Health Organization (WHO) in 2023. The American Heart Association has a long history of issuing scientific statements on nutrition and cardiovascular health, with over 150 statements published since 1993, including ones on salt, sugar, and alcohol consumption.

The organization previously released a scientific statement on caffeine and blood pressure in 2014, concluding that caffeine consumption could temporarily increase blood pressure, especially in individuals who do not regularly consume caffeine. A 2017 advisory warned of the risks of energy drinks, particularly for adolescents and young adults, recommending they avoid consuming them due to the risk of cardiovascular events, including tachycardia and arrhythmias. A 2021 statement outlined the importance of individual variability in caffeine metabolism, noting that people with certain genetic variants metabolize caffeine more slowly, increasing their risk of adverse cardiovascular effects.