In a comprehensive review paper, Dr. Gregory Marcus from the University of California, San Francisco, along with his colleagues, examined decades of research on the impact of caffeine—most commonly consumed through coffee—on cardiovascular health and its risk factors. They established that moderate caffeine intake is defined as up to approximately 400 mg per day, equating to around 3 to 5 cups of 8-ounce coffee (1 fluid ounce is 30 ml).
Dr. Marcus and colleagues found that moderate caffeine intake is safe and may lower the risk of various cardiovascular diseases, such as coronary heart disease, stroke, heart failure, atrial fibrillation, hypertension, and type 2 diabetes. Image credit: Sci.News.
Caffeine use has a rich history dating back to 2737 BC, making it the world’s most popular stimulant and psychoactive substance.
Presently, over 60 plant species, including cocoa beans and tea leaves, naturally contain caffeine, but it is also present in numerous commercial, prescription, and over-the-counter products.
Caffeine, a methylxanthine alkaloid, can be ingested through various means including orally, intravenously, topically, or rectally.
Owing to its 100% oral bioavailability and high hydrophilicity, caffeine is rapidly absorbed upon ingestion, reaching peak concentrations in just one hour.
While caffeine does not accumulate in tissues or organs, high concentrations (up to 80%) can be found in the brain.
The latest research reviewed by Dr. Marcus and his team indicates that consuming up to 400 mg of caffeine per day—comparable to 3 to 5 cups of regular black coffee without any added sugars or flavorings—is generally safe for most adults.
Regular non-specialty brewed coffee typically contains between 9.4 and 20.6 mg of caffeine per fluid ounce.
Dr. Marcus emphasizes, “Caffeine from coffee is an essential part of daily life for millions. Our review of the current research indicates that up to 400 mg of caffeine daily, which equals up to five cups of coffee without additives, is safe and does not elevate cardiovascular risk.”
He warns, “However, high doses of caffeine found in energy drinks, including energy shots, can be detrimental to heart health and should be avoided.”
According to the study, drinking black coffee with no added sugar or cream is linked to lower risks of type 2 diabetes, heart disease, strokes, heart failure, and some irregular heart rhythms.
Randomized trials, regarded as the most reliable research methodology, have demonstrated that coffee consumption reduces the risk of atrial fibrillation, although it may lead to an increased risk of premature ventricular beats.
Adding sugars, flavored syrups, milk, or cream may reduce the potential health benefits of coffee, necessitating further investigation into the impact of these additives.
High caffeine intake, such as that from energy drinks and shots, has been associated with cardiovascular issues like heightened blood pressure and irregular heart rhythms.
Energy shots can contain 40 to 69 mg of caffeine per fluid ounce, which is three to four times the caffeine content found in regular coffee.
Dr. Marcus reminds us, “While caffeine may offer cardiovascular benefits for some, it is crucial to acknowledge that there isn’t a universal guideline for safe caffeine consumption.”
“Individual responses to caffeine vary significantly based on factors such as age, medications, pre-existing health conditions, genetics, and metabolic rates.”
“What may be a tolerable dose for one person could result in adverse effects like heart palpitations, anxiety, and sleep issues for another.”
“Therefore, it’s essential to monitor your body’s response to caffeine and consult with your healthcare provider for personalized recommendations.”
For more details, refer to the review paper published in today’s edition of Circulation.
_____
Gregory M. Marcus etal. Caffeine and cardiovascular disease: A scientific statement from the American Heart Association. Circulation published online on July 20, 2026. doi: 10.1161/CIR.0000000000001454
Source: www.sci.news