Overview
- The AHA published a scientific statement on July 20 saying most adults can safely consume about 400 mg of caffeine per day, roughly five 8‑ounce cups of black coffee.
- Large observational studies reviewed by the AHA found that drinking about two to four cups of coffee daily is associated with lower risks of coronary disease, heart failure, stroke, type 2 diabetes and some abnormal heart rhythms, though those studies cannot prove cause and effect.
- The statement warns that high‑dose products such as energy drinks and energy shots may raise blood pressure and trigger abnormal heart rhythms and should be avoided.
- How coffee is brewed and served matters because paper‑filtered or instant coffee shows the strongest links to benefit while unfiltered methods raise LDL cholesterol through cafestol and added sugar or cream can negate benefits.
- The authors note large individual differences in caffeine response, driven by factors such as the CYP1A2 liver enzyme, age, medications and pregnancy, and they call for randomized trials to compare caffeine sources and resolve remaining causal questions.