People who drink two to four cups of caffeinated coffee a day showed a lower risk of developing heart disease, heart failure, and stroke.
According to the medical community on the 27th, the American Heart Association (AHA) presented these findings through a scientific statement titled "Caffeine and Cardiovascular Disease," published in the latest issue of the journal Circulation. The statement was prepared by experts from Harvard University and George Washington University, who reviewed dozens of existing studies on the effects of coffee and caffeine on cardiovascular health.
The AHA said that keeping daily caffeine intake below 400 mg does not increase cardiovascular disease risk for most adults. The 400 mg figure corresponds to three to five cups of regular black coffee in 240 ml servings. Because caffeine content varies depending on the type of bean, brewing method, and cup size, total daily intake rather than the number of cups should be used as the standard. Some studies found that drinking more than four cups a day actually increased the risk of heart failure. The statement drew a clear line, noting that intake closer to 400 mg does not mean it is more beneficial to health.
Black coffee consumption was also associated with a reduced risk of developing type 2 diabetes. However, most of the data reviewed by the experts came from observational studies that tracked people's lifestyle habits and disease occurrence over long periods. The statement concluded that while an association can be confirmed between coffee consumption and lower incidence of certain diseases, it is difficult to conclude that coffee directly reduces disease occurrence. The AHA specified that this statement does not constitute a clinical guideline recommending coffee consumption.
Results from randomized controlled trials varied by type of arrhythmia. In groups that drank caffeinated coffee, the risk of atrial fibrillation recurrence decreased, but the frequency of premature ventricular contractions, in which the ventricles contract earlier than scheduled, actually increased. The precise mechanism of action between coffee and reduced cardiovascular disease risk has not yet been identified.
While caffeine is said to block the action of adenosine, which induces drowsiness, and to increase physical activity, it also has side effects such as raising blood pressure, heart rate, and blood sugar in the short term and disrupting sleep. The possibility was also raised that the antioxidant and anti-inflammatory actions of bioactive substances such as polyphenols contained in coffee may play a role.
Some studies also found that decaffeinated coffee is likewise associated with a reduced risk of type 2 diabetes and heart disease, suggesting that components other than caffeine may influence the health effects.
The rate at which caffeine breaks down varies greatly between individuals depending on genetic factors, age, usual consumption habits, medications taken, and underlying conditions. Even when consuming the same amount, some people experience no particular symptoms while others suffer palpitations, anxiety, and sleep disorders.
Adding sugar, flavored syrups, and creamers high in saturated fat can reduce the health benefits expected from coffee, making it difficult to apply the findings on black coffee directly to sweetened or processed coffee beverages. The brewing method also affects cholesterol.
Espresso, French press, Turkish coffee, and boiled coffee, which do not use paper filters, contain cafestol, a substance that can raise low-density lipoprotein (LDL) cholesterol. Experts stressed that the findings from this coffee study should not be applied to energy drinks or energy shots. They recommended avoiding products containing high concentrations of caffeine, as they can raise blood pressure and increase the risk of arrhythmia.
