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.
However, caffeine ingestion in the range of 400 to 500 milligrams may cause nausea, abdominal discomfort and irritability. It elevates heart rate and blood pressure, which may affect the ability to accurately monitor training intensity.