DRHOOK- Joltin' Joe: Caffeine's many varied effects

Caffeine makes the world go round. As a child, I never liked my parents' instant coffee. It tasted like brown water to me. 

But when I was a college freshman and had to study all night long, I was really tired. So, one day, my friends had me drink a cup of coffee. I ended up walking into my calculus class all sweaty and tremulous and feeling like my heart was going to pop out of my chest.

Mind you, I always participated in class, but that day: "Dr. Mahoney, what does that mean? Oh, never mind! Wait, so if that equals that– Oh, never mind! Haha! Oo! So that means–"

Dr. Mahoney stared at me but eventually asked me why I was so wired. I told her that morning I had had my first real cup of coffee– and I had to pee.

 Is caffeine safe to use?

 Caffeine stimulates the brain. It helps people concentrate, focus, and stay awake. In fact, 80 percent of people in the world use caffeine. Caffeine is most commonly found in coffee, tea, cola, and chocolate. 

 Five ounces of drip coffee contains 146mg of caffeine; five ounces of percolated coffee has 110mg; five ounces of instant coffee has 53mg; one to two ounces of espresso has 45-100mg; a Starbucks venti has 415-550mg (hooray!); tea brewed one minute has 9-33mg, tea brewed three minutes has 20-46mg.

A 12-ounce can of iced tea has 22-36mg, a 12-ounce can of cola has 46mg, and one ounce of mild chocolate has 6mg. If I were Homer Simpson, I would say, "Mmmmm, caaaffeeeine."

 The effect of caffeine in coffee tends to peak in the first hour and can last up to eight hours, which is why it isn't a good idea to drink beverages with caffeine within eight hours of going to sleep. 

Caffeine in tea is chemically different from that in coffee and tends to peak a few hours later. Food can slow the absorption rate of caffeine, but it doesn't lower its total impact.

I love coffee. I didn't before, but I do now. I'd give up my car before I'd give up coffee.

But as with everything, too much of a good thing can have unwanted side effects. For example, once I was teaching a medical resident how to inject steroids into a patient's knee, and I had just downed a large cup of coffee. As I pointed to the knee to show where to inject, the patient grabbed my shaking index finger and asked, "Doc, have you done this before?" I responded, "Sure, I have injected many shoulders before. Haha."

 Fortunately, that patient's question did not irritate me, though caffeine can make people very irritable. The nervous system is all revved up which can cause nervousness, irritability, and excitation. 

 Many athletic drinks contain caffeine because it makes the heart pump harder, as well as getting the neurotransmitters known as catecholamines flowing—it can turn Droopy the Dog into a hyper Chihuahua. Ole! 

 Overall, normal caffeine use hasn't been shown to cause heart problems such as arrhythmias, heart attacks, or higher blood pressure. But in caffeine-naïve persons, caffeine has been shown to raise the systolic blood pressure by 10mm Hg. Also elderly folks and those with high blood pressure can have elevated blood pressure from caffeine. 

 People with heart arrhythmias or coronary heart disease are often advised not to consume caffeine because there is some evidence that caffeine use (especially two or more cups of coffee a day) presents an increased risk of heart attack and arrhythmias. 

 Also, smoking and caffeine synergize to harden arteries, which is another reason people shouldn't smoke.

 I wonder where my college math professor is now. (If you are reading this, "Hi, sorry I was such a spaz!") If I were she, I would teach at Columbia. I hear Columbia grows great coffee beans.


Dr. Hook cracks a joke or two, but he's a renowned physician with a local practice. Email him with your questions.