1 OPINION. 2  The screening process for Syrian refugees is much more rigorous than for other visitors coming to the U.S. (AP Photo/Hassan Ammar)
About 250 milligrams of caffeine â or the equivalent of 2 to 2 1/2 cups (473 to 591 milliliters) of plain, brewed coffee â a day may cause this effect. If you have type 2 diabetes and you're struggling to control your blood sugar levels, limiting the amount of caffeine in your diet may provide a benefit.
Too Much Caffeine. Consuming too much caffeine can cause chest pain, chest tightness and an increased heart rate. Caffeine affects people differently, depending on weight, normal caffeine consumption and other medical conditions. MayoClinic.com states that the average adult can consume between 200 to 300mg of caffeine daily without causing any harm. If you drink 500mg or more, you may develop adverse reactions, such as chest pain.