Caffeine: The Most Widely Used Stimulant in the World

Caffeine is the most widely used stimulant and psychoactive substance globally, and coffee is the primary source of caffeine for most people. According to a new scientific statement from the American Heart Association, most adults can safely consume up to 400 mg of caffeine per day, or up to five 8-ounce cups of caffeinated coffee per day.

For some individuals, moderate coffee consumption may also be associated with a lower risk of cardiovascular disease. The picture changes at higher doses, however. Concentrated sources of caffeine, particularly energy drinks, including energy shots, may raise the risk of cardiovascular problems.

The American Heart Association’s Scientific Statement

The American Heart Association’s scientific statement, published in the journal Circulation, emphasizes the importance of understanding the effects of caffeine on the cardiovascular system. The statement highlights the difficulty in distinguishing the effects of caffeine from those of other substances in coffee, such as milk, cream, flavored syrups, and sugar.

Experimental research suggests that some bioactive compounds in coffee have antioxidant and anti-inflammatory properties, which may contribute to its potential benefits. However, more studies are needed to clarify the caffeine content and cardiovascular effects of other products that contain caffeine, such as tea, chocolate, soda, and over-the-counter and prescription medications.

Safe Caffeine Intake and Cardiovascular Risks

Based on the latest studies included in the review, up to 400 mg of caffeine per day is considered safe for most adults. This amount is roughly equivalent to no more than 3 to 5, 8-ounce cups of regular black caffeinated coffee per day without added sugars, sweeteners, flavors, or fillers.

Regular brewed, non-specialty, caffeinated coffee usually contains 9.4-20.6 mg of caffeine per fluid ounce. Drinking caffeinated coffee without added sugars, flavors, or cream was associated with lower risks of Type 2 diabetes, heart disease, stroke, heart failure, and some irregular heart rhythms.

Concentrated Sources of Caffeine and Cardiovascular Problems

Concentrated sources of caffeine, such as energy drinks and energy shots, may raise the risk of cardiovascular problems. Energy drink shots may contain 40-69 mg of caffeine per fluid ounce, 3-4 times more caffeine than regular caffeinated coffee.

High caffeine intake may pose greater risks. Levels commonly found in energy drinks were associated with high blood pressure and irregular heart rhythm. Very high caffeine doses, such as those in caffeinated energy drinks or energy shots, have been associated with abnormal heart rhythms even in people who are normally considered at low risk for cardiovascular disease, including healthy adults younger than age 30.

Additional Research Needed

Researchers emphasize that caffeine products should not all be treated as interchangeable. More studies are needed to compare different kinds of caffeinated coffee with tea, soda, energy drinks, and energy shots, and foods. Tea has received less research attention than coffee, but tea consumption has been associated with reduced risks of atrial fibrillation, heart failure, and stroke, similar to caffeinated coffee.