Saturday, March 10, 2007

Caffeine: Threat or Menace?

Like many people, I like coffee. I drink coffee almost every day. My online alter-egos typically have coffee mugs in their hands (see: the display picture in this blog). I love the smell of freshly ground coffee, and I love the taste of a perfectly brewed cup. Sadly, my coffee maker at home doesn’t always make for the best cup of java, so I sometimes add brown sugar, milk, or (rarely) hazelnut flavoured oil-based milk-like product. And yes, I’ll admit it, I enjoy the physiological effects of coffee as well. I’ve tried to figure out how to add coffee to various foods, from muffins to tacos to chili to cookies, all with varying degrees of success. I’ve even read books on coffee, and always found the historical and cultural aspects of the beverage fascinating.

Caffeine, on the other hand, I knew much less about. I know that it’s a stimulant, and I know that it’s a diuretic, but other than that, I was clueless. Until I spent an hour at my computer, that is. Now, I’m afraid I may know too much. (Sources: Caffeine entry at Wikipedia, “How Caffeine Works” at, and “Caffeine-Related Disorders” at The Encyclopedia of Mental Disorders.)

Caffeine can be found in many different foods and drugs, some obvious, some not. Coffee, tea, cola, chocolate, various energy drinks, and headache medications all contain some amount of caffeine. (Why do medications like Anacin have caffeine? Because if you have a vascular headache, caffeine constricts the blood vessels, thereby reducing the headache.) Caffeine is a stimulant for the nervous system and for the metabolism, leading to increased alertness and focus, increased lipid breakdown, and improved reflexes. But you probably already knew that. Here are some more interesting tidbits.

Different foods have different amounts of caffeine. Here’s an interesting list that I’ll be referring to later:

Approximate Amount of Caffeine per Serving
- Brewed Coffee (6-oz cup) - 100 mg
- Brewed Tea (6-oz cup) - 70 mg
- Espresso (2-oz shot) - 100 mg
- Regular Cola (12-oz/354 ml can) - 50 mg
- Jolt Cola (12-oz/354 ml can) - 70 mg
- Red Bull (8-oz/240 ml can) - 80 mg
- Milk Chocolate (1 oz/30 g) - 6 mg
- Anacin (1 tablet) - 32 mg
- Dexatrim (appetite suppressant; 1 tablet) - 200 mg

Most people take their coffee in large travel mugs or paper cups from coffee shops, so their “cups” of coffee are more like 12, 16, or 20 fluid ounces. That’s 200, 260, or 330 mg of caffeine per cup. At an average of eight to eleven 6-oz cups of coffee a day, I consume nearly one gram of caffeine a day. To compare, the Peach likely has a maximum of 100 mg per day, if she has a mug of tea and a chocolate bar. Then again, I’m about double her mass, so it’s a pretty bad comparison all around.

Caffeine has a really complex metabolism, but essentially it blocks adenosine receptors; since adenosine slows neural activity, causing drowsiness, when caffeine binds to those, it instead causes increased neural activity, which causes increased production of adrenaline. So, not only do you NOT get drowsy, but your body gets primed. Adenosine antagonism also leads to increased production of dopamine and serotonin, leading to a stimulatory effect and improved mood. (Adenosine antagonism may contribute to caffeine’s diuretic effect.) While humans can metabolize caffeine just fine, it’s actually harmful to other animals like dogs and horses. Caffeine severely disrupts spiders as well, making me wonder if there are any comic books out there that show Peter Parker going on a caffeine-induced bender through New York City, and if not, why not.

Like all drugs, regular intake of caffeine can lead to tolerance. Caffeine tolerance builds up rather quickly: complete tolerance to the mood and attention improvement of caffeine develops after daily consumption of 300mg of caffeine over 18 days. That means that if you have one large cup of coffee from your favourite chain coffee shop every day, you’re tolerant. In fact, look at that list again. You have 2 cans of coke and a small cappucino? Same thing. Your mileage and metabolism may vary, of course, but still: that’s a lot. Essentially, anyone who has coffee every day isn’t getting a “boost”, you’re fighting off the crash that comes when the adrenaline wears off: headaches (because your blood vessels expand), anxiety, irritability, reduced motivation, and sometimes depression. It only takes 1-5 days to withdraw from caffeine, but most people don’t last that long. It’s easier to just have another Coke.

The DSM-IV, the handbook of mental disorders, lists four caffeine-induced psychiatric disorders: caffeine intoxication, caffeine-induced anxiety disorder, caffeine-induced sleep disorder, and caffeine related disorder not otherwise specified. That’s right: some people consume so much caffeine (or metabolize it so badly) that they have psychiatric disturbances that merit clinical attention. A diagnosis of caffeine intoxication requires the presence of at least five of the following symptoms, and it can’t be better explained by a different medical or mental disorder: restlessness, nervousness, excitement, insomnia, flushed face, diuresis (increased urinary output), gastrointestinal disturbance, muscle twitching, talking or thinking in a rambling manner, tachycardia (speeded-up heartbeat) or disturbances of heart rhythm, periods of inexhaustibility, and psychomotor agitation. Because tolerance builds up so quickly, though, caffeine intoxication is typically encountered in people who don’t normally consume very much, or who have dramatically increased their intake, like a college student during exam week, or an expectant father during a 36-hour labour; bad situations made worse, so try to avoid drinking 2 pots of coffee every day during finals (personal experience AND science talking here).

Caffeine has been linked with the reduction in the risk of Parkinson’s and heart disease, and might even prevent baldness. However, anyone thinking that a couple of extra glasses of tea would stop that hairline from receding, it takes at approximately six grams of caffeine to result in enough making it to your hair follicles, so you’d be better off washing your hair with Jolt Cola than drinking more of it. Besides, you’d get caffeine intoxication LONG before you’d see any result on your scalp.

So, that’s my weekly knowledge dump, for better or worse. Anyone out there consume more caffeine on a daily basis than I do? Look it up in the list, let me know. I’d feel better, at least.


Mrs. Loquacious said...

Currently I have given up chocolate and coffee for Lent, so my only intake is in the form of steeped tea. I think I take in about 140-210mg of caffeine from tea on a daily basis (yes, 3 cups or so).

However, when it is not the Lenten season and I'm in the classroom, I generally have 1 mug of tea and 2-3 mugs of coffee each day, which adds up to about 375 mg.

I know I'm tolerant though, because coffee no longer gives me any "jolt" or keeps me awake; I can literally have a cup and then go straight to sleep.

Personally, I figure that since I don't get drunk and I don't do drugs and I don't smoke and I don't have a whole lot of vices, coffee being my only big bad dark secret is not such a bad thing. And it tastes so heavenly!

I can't wait until Easter!!

Jo-Jo said...

I've discovered I'm getting old. I can no longer have a cup of coffee at 10:00pm and then expect to sleep.
About two or three weeks ago I went off coffee for about a week. By the end of the week I had a cup of coffee to wake me up to go to the Barenaked Ladies concert, and for some strange reason I was much more happy! Later that night G commented that maybe I shouldn't give up coffee until I was finished school. Nice and subtle of him...

Shannon said...

Excellent post! It made me feel guilty about my 2.5 cup a day habit. Maybe it's time to cut back, if only to get my buzz back?

Natalie said...

Wow, thanks for all the info. I don't drink coffee, tea or soda and I rarely eat chocolate. Yet, caffine dosn't really do much for me. I must be a mutant type person.

Nezbitt said...

Ok, Mr. Science. I need you to figure something out for me.
I can't drink cola. It gives me the most terrible headaches. I always figured it was the caffeine. (I put two and two together the night I drank a can of Red Bull; also know as the night of a thousand pains.)
But I eat chocolate like someone is going to take it away from me. Does it have to do with the amount I'm consuming? Or is there a difference between solid and liquid form? And why does it cause so much PAIN??

The Doc said...

Mrs. L, even though I drink a lot of coffee, I still get some kind of reaction when I drink it, even if it is just the haze lifting from my brain. Also: I have a very different definition of what a "big bad dark secret" is than you do.

Jo, I've been saying I'm going to give up coffee for a week for...years now. Still haven't done it. Maybe I too will wait for the after-school season.

Shannon, 2.5 cups? Wuss!

Natalie, with your mutant power to metabolize caffeine, you should join the X-Men! Or at least the Legion of Superheroes.

Nez, I think you hit upon your own explanation for why caffeine chocolate doesn't affect you (if it is caffeine that gives you those headaches, which is possible). In order to get the amount of caffeine that's in one can of Coke, you'd need to eat over seven Aero bars. I know you eat a lot of chocolate, but you don't eat THAT much chocolate. As for why the headaches, I don't know. I'll keep thinking on it.

Jeans said...

I think I'm a social outcast because I don't like the taste of coffee. I can't even eat cappuccino ice cream or wear mocha flavored lip balm. Now that I read your post, I'm kind of glad!

The Doc said...

Jeans, although my brain reels at the whole "not liking coffee" business, don't worry; as I listed before, there's plenty drug delivery systems for caffeine. You probably get plenty without the sweet, sweet bean.

Jeans said...

Just hook me up to an IV and pour chocolate down the tube!