75% of children and adolescents from ages 6-19 use caffeine on a daily basis. More than 85% of all adults in America use it daily. We all rely on this drug, but how does it work and what might be some of the repercussions of its consumption? How much is considered safe for the average adult?
Caffeine is found naturally in cocoa beans, coffee beans, tea leaves, and guarana leaves. Energy drinks you might buy at the store most likely get their caffeine from guarana leaf extract. However, these are not the only places you might find caffeine. Caffeine has also been added to sodas, gum, juice, painkillers, and even hygiene and beauty products like shampoo, body wash, and eye cream. The next time you see products that claim to “give you energy,” or “age-defying,” there’s a good chance that there’s caffeine somewhere.
Caffeine works by bonding to our adenosine (A2) receptors in the brain. Adenosine, as you might expect, is an inhibitory neurotransmitter that depresses the central nervous system, making you want to sleep. As the day goes on, you accumulate more adenosine that can’t be cleared until you fall asleep. However, since caffeine and adenosine are very close in shape with their 4 carbon, 2 nitrogen rings, caffeine is able to bond to our A2 receptors, stopping adenosine from telling our brains that we’re tired.
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Caffeine, for the most part, is healthy and will not cause harm. Since it takes the place of adenosine, the benefits of caffeine include: increased alertness, faster reaction time, and improved memory. These effects are also more profound if you’re suffering from mild caffeine withdrawal or sleep deprivation. It’s also been found to relieve pain; when used in conjunction with acetaminophen (Tylenol), it was found to reduce the necessary dosage amount by 40%. It may even reduce your chance of obtaining Alzheimer’s and Parkinson’s disease.
However, caffeine also has many downsides. First and foremost, its ability to keep you awake for long periods of time can begin a positive feedback loop in which you sleep less and drink more caffeine to stay awake. This may lead to increased anxiety, daytime drowsiness, and anger. Its obstruction of adenosine is also problematic as adenosine normally helps with regulating heart rate, so arrhythmia (irregular heartbeat), and increased heart rate are both side effects of caffeine. Lastly, for pregnant women, caffeine is detrimental to prenatal development as infants have not developed the enzymes necessary to metabolize caffeine. As a result, caffeine may increase the chance of miscarriage, lower birth weight, and hinder development.
So if caffeine is safe, how much is considered healthy? For the average adult, around 400 milligrams, or 4 eight ounce cups of coffee a day is the upper limit before one experiences noticeable side effects. For adolescents, there is no magic number, but the European Food and Safety Authority considers 3-mg/kg body weight/day of habitual caffeine consumption to be safe. To calculate this amount for yourself, take your weight in pounds, divide it by 2.2 and multiply by 3. This is the amount in milligrams that you should not surpass per day. It is also important to note that caffeine concentrations peak from 15-120 minutes after ingestion, so try not to take too much at one time as well. This peak can be exploited for good as well though, as taking a “coffee nap” has been proven to be effective at giving a large amount of energy in a short period of time. To try this yourself, drink one cup of coffee, around 80-100 milligrams of caffeine, and then take a 20 minute nap. Your brain will clear some adenosine as you sleep while caffeine enters your brain and blocks the A2 receptors that were just cleared.
Go get yourself a coffee, and drink responsibly.