Caffeine - How much do you take?

Regular doses of caffeine have been the subject of countless medical studies. We know the substance effortlessly crosses the blood-brain barrier, creating swift and rewarding effects. Caffeine works by dampening neurotransmitters that would normally make you sleepy, improving—temporarily—cognitive function and even athletic performance. Exactly what level of caffeine is harmful is not clearly established, but generally more than five [8 oz., or 240 mL] cups of coffee is too much.

It’s technically possible to die from a caffeine overdose, but, says Dr. Eric Lavonas, a North Carolina emergency-room doctor and a spokesman for the American College of Emergency Physicians, “you have to really work at it.” Far more common are people who simply fall ill from eating or drinking too much of the stuff. The jitters and stomachaches are the most common symptoms of taking in too much caffeine. Worse, to hear many caffeine addicts tell it, is the way you feel when you stop suddenly. Withdrawal symptoms include headaches, fatigue, jitteriness, nausea, diarrhea and tremors. Other side effects of withdrawal include palpitations, sleeplessness and cramps. . The highest caffeine boost can be felt one hour following ingestion, but significant effects can last for eight hours. If you’re at risk for heart disease, hypertension or digestive disorders, talk to your doctor about how much caffeine—if any—you should be drinking. Like any pleasurable substance, caffeine can be abused. So enjoy—but with care.