Caffeine... Is It Really All That Bad?

Caffeine (kaf-en') - an alkaloid drug, obtained from coffee and tea, that has a stimulant action, particularly on the central nervous system. It is used to promote wakefulness and increase mental activity.

Sources and Related Compounds

Caffeine is one in a group of compounds known as methylxanthines. The other two compounds are theobromine and theophylline and are found in cocoa and tea, respectively. Caffeine is found in coffee, tea, cocoa beans, and kola nuts. The following table lists average amounts of caffeine in the most common sources:

Source of Caffeine


Coffee (10 oz.) brewed, drip


Coffee (10 oz.) instant


Coffee (10 oz.) decaf


Tea (10 oz, brewed)


Iced tea (12 oz)


Hot cocoa (8 oz)


Soft drink (12 oz) Coca Cola




Dr. Pepper


Diet Coke/Pepsi


Mountain Dew


Anacin (2 tablets)


Exedrin (1 tablet)


No Doz (1 tablet)


The Physiology of Caffeine

Caffeine is absorbed rapidly and is distributed throughout the body water within about an hour. It has a metabolic half life of about three hours and is excreted as a methylxanthine derivitive (in both urine and to a lesser extent, feces). Caffeine is a cardiac muscle stimulant, smooth muscle relaxant, and a central nervous system (CNS) stimulant. One mechanism behind the latter is an increase in the excitiability of neurons in the CNS. Caffeine also acts as a diuretic, stimulates gastric acid secretions, and increases plasma glucose and free fatty acid concentrations. These physiological effects of caffeine are related to both the drawbacks and benefits of this drug.

The Drawbacks of Caffeine

The Benefits of Caffeine

Who Should Avoid Caffeine?

Caffeine should be avoided by those with any of the following clinical conditions:

This is not meant to be a comprehensive list by any means, but these are some of the major conditions where caffeine should be avoided. Also, patients should be made aware of any caffeine found in medications in case they are sensitive to certain levels of caffeine.

The Bottom Line

Most of the studies linking caffeine (coffee consumption) with health problems are inconsistent. Increased caffeine consumption has been associated with elevated cholesterol, fibrocystic breast disease, rapid heart beat, and some cancers. Studies showing either a relationship or no relationship seems to be about equal in number. In 1986 the American Journal of Epidemiology reported a 25 year follow up study on 3000 people which showed that men who drank more than 5 cups of coffee a day had an increased mortality - but this was not the case for women. The jury is obviously still out on the hazards of caffeine, but most of the studies showing some link between caffeine and a health risk report levels of more that 4 cups of coffee a day. In my opinion, caffeine is like anything else - used in moderation (200 mg a day or so) it is probably harmless. For those of us who choose to consume that tasty beverage called joe, it's important to recognize some of the drawbacks and make sure we minimize them. If you can't function on less than 4 cups a day - I would definitely consider cutting back slowly down to a more moderate level. If you really enjoy your one cup a day - relax and enjoy!

For more information, please contact the Nutrition Office at 621-4550.

Written by: Paige Holm, R.D. Sources: Tribole, Evelyn R.D., "Eating on the Run" Werbach, Melvyn R. M.D., "Nutritional Influences on Illness" 2nd ed. Clark, Nancy M.S., R.D., "Sports Nutrition Guidebook" 2nd ed. Zeman, F.J., "Clinical Nutrition and Dietetics"