Caffeine, the most popular drug

November 20, 2004

by Laura Dolson

What is caffeine? Caffeine is a substance which occurs naturally in some plants - coffee and cacao (chocolate) beans and the leaves of the tea plant are the most common sources. These plants are often used in beverages, or food in the case of chocolate. Caffeine is also added to other beverages and some medicines.

There are other naturally-occuring compounds in the same family as caffeine with some similar and some different effects. Theophylline is found in tea, and theobromine in chocolate.

Why do people like to drink beverages containing caffeine? Caffeine is often called "the most commonly used drug in the world". People like its stimulating effect - it makes them feel more alert. For certain kinds of tasks, caffeine improves concentration and reaction time.

What does caffeine do in our bodies? Caffeine blocks the effect of a neurotransmitter in our brains that normally works to relax us. Also, it causes the body to secrete more of the hormone adrenaline, the substance that "revs up" our nervous systems in a similar way to stress. Our heart rates and blood pressure increase slightly, as well as the other effects of a mild "adrenaline rush".

What are the negative effects of caffeine? The negative effects of caffeine come in three categories:

1) Short-term effects - People who have too much caffeine can get nervous and jittery. Their hearts may race, and their hands may shake a bit. It may be harder to solve complex problems. They may have trouble calming their minds and bodies down, and often have trouble sleeping. At higher doses, headaches and stomach disturbances can occur. In very large doses, caffeine is toxic.
2) Long-term effects - Caffeine can cause calcium loss, so unless a person consumes extra calcium, long-term high caffeine use can lead to osteoporosis. One study showed that teens who drink caffeinated beverages regularly have slightly higher blood pressure. Pregnant women should not use much if any caffeine, as it stays in the baby's system longer, and can lead to having a baby with low weight, which in turn can cause problems for the baby. However, the current thinking is that caffeine does not generally lead to serious diseases like cancer or heart disease.
3) Poor health practices - This is perhaps the most risky of the effects of regular caffeine use. Caffeine users can easily get into the habit of drinking caffenated beverages when tired or needing a break from work, when it would be healthier to perk themselves with a quick walk or a short nap. In other words, it can become a crutch to make up for poor health practices. The following are healthier ways to make sure you keep your energy high and stay productive:

A) Get enough sleep! This is very important for good health. If you are chronically underslept, you will be amazed at how much better you feel with regular sleep in adequate amounts.
B) Eat a good diet. In particular, high sugar diets can send your body on an energy roller-coaster which might tempt you to use caffeine to get you through the "dips". Eat an adequate amount of protein, and a variety of vegetables, fruits, whole grains, nuts, and legumes.
C) Get enough regular exercise. Stay active. Walk, ride your bike, dance, or play sports on a regular basis - anything that makes you feel good. It's easy to get feeling "bogged down" without regular activity. If you feel like reaching for a caffeinated drink, try putting on your favorite music and dancing for a few minutes, or run outside and practice your soccer or other sports skills.

Is caffeine addictive? Yes, although it is considered to be "mildly" addictive, because with some effort an addicted person can "get off" caffeine and won't continue to have the same level of cravings as many other addictive drugs.

What does "addictive" mean in regards to caffeine? The word "addictive" has a lot of different meanings. I am using the term in the classic biological sense to mean that it has two distinct properties:

1) Tolerance - Taken regularly, the body adapts to the drug and gradually needs more of it to achieve the same effect.
2) Withdrawal - When a person stops taking the drug, they feel bad - in the case of caffeine, this means headaches, fatigue, and irritability. People who are addicted to their morning coffee will feel bad (usually groggy and somewhat grumpy) until they have had their coffee.

Caffeine addiction can be avoided by not using caffeine too regularly, or in large quantities, and by varying the amount of caffeine so the body doesn't get used to it.

How much caffeine is safe? Different bodies have different sensitivities to caffeine, so it's difficult to say. Generally, adults are recommended not to go over 300 mg per day. There aren't guidelines for kids in the US, but in Canada, the recommendation is that middle school-aged kids consume no more than 85 mg per day (less for younger children).

How much caffeine is in various beverages and foods? This is harder to say than you'd think. If you look at charts of this sort of thing, you will see that the amount of caffeine in a naturally-derived product (coffee, tea, chocolate) is quite variable. This is simply because plants are living things which vary in a lot of ways from species to species and plant to plant. Also, the way the beverage is prepared makes a big difference - how long the tea is brewed, for example. Here are some averages:

Cola Beverages 30-55 mg/can
Sunkist Orange Soda 40 mg/can
Minute Maid Orange Soda no caffeine
Mountain Dew 55 mg/12 oz
Jolt Cola 70 mg/12 oz
7-11Big Gulp Cola 190 mg/64 oz
Häagen-Dazs Coffee Ice Cream 58 mg/cup
Dannon Coffee Yogurt 45 mg/cup
Hershey Milk Choc Bar 10 mg/1.5 oz bar
Hershey Special Dark 31 mg/1.5 oz
Baking Chocolate 35 mg/oz
Hot Cocoa or Chocolate Milk 4-8 mg/8 oz
Coffee, drip 90-150 mg/ 8 oz
Coffee, instant 60-100 mg
Coffee, "gourmet" up to 270 mg
Coffee, espresso 50-100 mg/serving
Tea, black 20-60 mg/8 oz (up to 110 mg)
Tea, green 10-36 mg/8 oz

Questions for Discussion: What is a drug? How can we go about making decisions about substances such as caffeine?

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