The American Heart Association (AHA) indicates that consuming three to five 8-ounce cups of black coffee per day can be part of a healthy diet for most adults. This level of consumption is also associated with a decreased long-term risk of heart failure, according to research published in Circulation: Heart Failure. Specifically, studies suggest that the risk of heart failure decreased by 5% to 12% per cup per day of coffee compared to non-consumption, with some studies showing a 30% lower risk for those drinking at least two cups a day. The AHA emphasizes that these benefits apply to plain black coffee, as popular coffee-based drinks often contain high levels of calories, added sugar, and fat.
While caffeine consumption from any source appears to be linked to a reduced heart failure risk, the AHA notes that there isn't enough evidence to recommend increasing coffee consumption solely for this benefit, with the same certainty as other heart-healthy practices like smoking cessation or exercise. They caution that caffeine is a stimulant and excessive intake can lead to jitters and sleep problems. The Food and Drug Administration (FDA) generally considers up to $400$ milligrams of caffeine a day safe for healthy adults, which is equivalent to about four or five cups of coffee.
However, individual responses to caffeine vary significantly due to factors like metabolism, body weight, and medication use. For individuals with severe high blood pressure ($160/100$ mm Hg or higher), drinking two or more cups of coffee daily may double the risk of death from cardiovascular disease. In contrast, one cup per day does not show this increased risk. The AHA advises individuals experiencing sleep problems or abnormal heart rhythms to experiment with reducing their caffeine intake. Children and adolescents are generally advised to avoid caffeinated beverages.
Decaffeinated coffee, surprisingly, did not show the same benefits and in one study, the Framingham Heart Study, it was associated with a significantly increased risk of heart failure. However, another study, the Cardiovascular Health Study, found no such increase or decrease. The research on coffee's effects did not specify details like coffee bean origin, preparation methods (e.g., drip, espresso), or exact cup sizes, which could influence caffeine levels and outcomes. These findings are also specifically about coffee and caffeine, and thus may not extend to other caffeinated products like energy drinks or teas.
