Coffee drinkers come in all shapes and sizes. Some brew it as part of their wake-up routine. Some buy from Dunkin’ Donuts before studying for a midterm. And some wait on a line out the door of the Stony Brook Union Starbucks at noon.
A survey by Gallup found that just under two-thirds of Americans drink at least one cup of coffee a day.
But what actually happens when people pour this bittersweet elixir down their throats?
“Once it hits your system, coffee is usually in your bloodstream for the next half an hour to 45 minutes depending on what you put in it,” Stephanie May, the registered dietitian at Stony Brook University’s Campus Dining Services, said. “If you have a lot of milk and syrups and things like that, that will slow down the digestion in your stomach, and it will hit a little bit later.”
The most active ingredient in coffee is caffeine, the most widely used psychoactive substance in the world. Caffeine is an alkaloid. Alkaloids are naturally-occurring chemical compounds made up mostly of basic nitrogen atoms.
About 45 minutes after drinking coffee, the caffeine gets into your brain and starts competing with adenosine to pair with adenosine receptors, according to Christian Sheline, a research associate professor of neurology and Neurosciences Institute administrator at Stony Brook University.
Normally adenosine, another alkaloid, builds up in the brain throughout the day, Sheline explained in an email. As it gets more concentrated, it binds with adenosine receptors, slowing down nerve cell activity and making you sleepy. But caffeine, which looks similar to the part of adenosine the receptors care about, gets in the mix and bonds to the receptors instead, preventing that message of fatigue from being delivered.
If human brains were a high school movie, caffeine would be the bad boy who easily asks the receptor on a date while adenosine is still building up his confidence.
This binding leads to increased neuron firings, so the pituitary gland, thinking that this is some kind of emergency, sends a message to adrenal glands to produce adrenaline. The adrenaline increases your heart rate, your blood flow to the stomach and muscles and your blood pressure.
Being the bad boy that it is, caffeine increases the dopamine level in your system in a way that is similar but weaker to that of heroin and cocaine, which are also alkaloids. Dopamine is the neurotransmitter that activates the pleasure centers in your brain.
This also leads to the cycle of caffeine addiction. When you drink a strong cup of coffee with around 200 milligrams of caffeine at 5 p.m., you will still have around 100 milligrams of caffeine in your head at 11 p.m.. You might be able to sleep, but you are not going to get the deep sleep your body needs.
May recommends drinking four or fewer cups of coffee per day.
“You need to specify what a cup is,” Melissa Buscetta, the Stony Brook dietetic intern, said. “Eight ounces. Not one of those grande cups at Starbucks.”
A grande-sized cup at Starbucks is 16 ounces.
This does not mean coffee is bad. Coffee drinking has long-term benefits. In November 2015, the American Heart Association published a study stating that people who drank a moderate amount of coffee — fewer than five cups per day — experienced a lower risk of death from type 2 diabetes, cardiovascular diseases, neurological diseases and suicide. The study followed 167,944 women and 40,557 men for up to 30 years, checking in every four years. The benefits held true for those who drank either caffeinated or decaffeinated coffee, suggesting that they were caused by naturally occurring chemical compounds in the coffee beans.
Other studies have found coffee consumption to be associated with lower risks of Parkinson’s and Alzheimer’s disease, to have a favorable effect on liver function, to possibly help with weight loss and to decrease risk of developing certain cancers like endometrial, prostatic, colorectal and liver cancer.
So as long as you balance it out, feel free to raise a mug — or four — and toast to good grades and good health.