How Much Coffee Is Too Much?

If you don’t feel like a fully functioning human until you’ve inhaled a steaming mug of coffee in the morning, you’re not alone. Sixty-four percent of Americans report drinking at least one cup on average a day, according to a Gallup poll, and the appeal actually increases with age.

While 50 percent of 18- to 34-year olds consume coffee daily, 74 percent of adults 55 and older say they do the same, the poll reports. While the mental jolt you experience after a java fix is very real, research suggests there may be some additional benefits to your morning or midafternoon cup, as well as a few potential drawbacks.

Best part of waking up

First, a quick lesson in why you experience that brain boost about 30 minutes after finishing your first cup: That feeling of being awake and alert results from several chemical interactions in the body. Caffeine, a stimulant, blocks receptors for the chemical adenosine, which normally prevents the release of brain-sparking chemicals. “By blocking adenosine receptors, caffeine temporarily prevents this signal from making you feel sleepy,” despite the continued accumulation of adenosine in the brain throughout the day, says Michael Grider, director of the neuroscience program at High Point University in North Carolina.

Caffeine also affects two key hormones: cortisol and adrenaline. Grinder explains that adrenaline increases alertness, heart rate, blood pressure and body movement. “Cortisol is the body’s main stress hormone, and it increases the body’s stress response.”

In addition, caffeine increases the activity of a group of neurons known as cholinergic neurons, which are involved in attention and arousal, Grider adds. This is another reason for the short-term increase in focus on a test or work project, for example, that is associated with caffeine intake.

Morning jolt

All three of these chemical reactions in the brain increase attentiveness. “The more attentive we are, the more we tend to remember,” says James Giordano, a professor in the neurology and biochemistry departments at Georgetown University Medical Center in Washington, D.C. A study published in the Journal of Nutrition found that on tests of mental function, subjects who consumed caffeine had better scores, particularly among older adults. “Indirectly, caffeine is a tool to improve certain types of learning,” Giordano says.

How long does the increased attentiveness last? Research published in Nature Neuroscience shows that caffeine enhances certain memories for up to 24 hours after consumption. “A moderate dose of caffeine can facilitate the short-term retention of information, which then has a good shot of being encoded into long-term memory,” Giordano says. (An important footnote is that, in scientific jargon, “short-term memory” is between seven and 15 seconds, whereas “long-term memory” is measured in minutes and hours, not in years, as you might imagine.)

To learn more about how coffee and brain health, read this article in Staying Sharp.

_{This content is provided for informational purposes only and is not intended to provide any expert, professional or specialty advice or recommendations. Readers are urged to consult with their medical providers for all questions.}