What is caffeine?

Caffeine is one of the world's most widely used drugs. Some anthropologists believe its use may date back to the Stone Age. Pharmacologically, caffeine is one of a group of stimulants called methylxanthine, or xanthine, that occur naturally in some plants. Beverages made from the nuts, seeds or leaves of these plants are major sources of natural caffeine, such as coffee, made from the Coffea arabica plant; soft drinks, like Coca Cola, made from Kola nuts; and tea made from the leaves of Thea sinensis. Cocoa, used to make chocolate, contains caffeine as well as theobromine, another xanthine.

Caffeine is also used as a food additive regulated by the Federal Food and Drug Administration (FDA). Food and beverage manufacturers are legally required to list caffeine on their products' label only when caffeine has been added. Caffeine naturally present in other ingredients used in the production process need not be on the label. For example, chocolate contains caffeine, so it may not be listed as an additive in candy bars. People who wish to avoid caffeine need to be aware of such natural, plant sources when making food choices.

The FDA also regulates caffeine's use as a stimulant in some over-the-counter and prescription medications. Consumers will commonly see caffeine listed as an active ingredient in some stimulants, cold remedies, and various pain killers.

For the caffeine content of coffee, tea, soft drinks, and medications, please read on.

Which types of coffee contain the most caffeine?

The caffeine content of an average 5 ounce cup of coffee can vary from 40–150 mg. Two influencing factors are the variety of coffee bean and where it is grown; both can be affected by such things as soil conditions, length of growing season, and time of harvest. Even coffee grown in the same general region will vary in caffeine content.

Three more controllable factors are how finely the beans are ground before coffee making and the method and length of time used for brewing the coffee. The drip method, with fine ground, used in machines like Mr. Coffee, generally yields the highest amount of caffeine, ranging from 110-150 mg per five ounce cup. Percolated coffee is next highest in caffeine, ranging from 64-124 mg. Isn't it interesting that many people say that brewed coffee tastes best? Instant coffee may be lower in caffeine averaging between 40–108 mg per cup.

Decaffeinated coffee, despite its name, does contain some caffeine, although only about 2–5 mg per five ounce cup. (See the chart below for comparison)

[From Consumers' Union, Food and Drug Administration, National Coffee Association of the U.S.A., and National Confectioner's Association of the U.S.]

Are decaffeinated beverages really caffeine free?

Not completely. The decaffeination process of coffee and tea effectively removes about 97% of the caffeine, leaving approximately 2–5 mg in a cup of coffee. (A regular cup of coffee contains 40–150 mg of caffeine). Decaffeinated soft drinks may also contain traces (0–.09 mg) of caffeine.

Are harmful chemicals used in the decaffeination process?

Two basic decaffeination processes are used in the U.S.: water extraction and direct solvent extraction. In the water extraction process, the coffee beans are steamed and then soaked and rinsed, allowing the caffeine to diffuse from the beans into the water, using no artificial chemicals.

In the direct solvent extraction process, decaffeination is accomplished by direct application of methylene chloride, ethyl acetate or carbon dioxide to the coffee beans. The beans are then steamed to remove the residual solvent, then dried and roasted. Methylene chloride received a great deal of attention when it was found to be an animal carcinogen when given by inhalation. Yet, the administration of methylene chloride to mice in drinking water (which more closely resembles human exposure through coffee drinking) resulted in no adverse health effects.

The FDA continues to permit the use of methylene chloride to decaffeinate coffee because it has determined that any potential health risk is so low "as to be essentially non-existent" (FDA, 1985).

How much caffeine is in tea?

An average 5 ounce cup of tea can contain 20-ll0 mg, making it the next highest source of caffeine in beverages. How much caffeine is in your cup of tea will depend upon the type of tea used, the tea leaf cut, and how long it was brewed. Tea drinkers may be interested to know that besides caffeine, tea contains another stimulant--theophylline. (See the chart below for comparison.)

[From Consumers' Union, Food and Drug Administration, National Coffee Association of the U.S.A., and National Confectioner's Association of the U.S.]

What stimulant besides caffeine is in tea?

Tea also contains theophylline, another member of the xanthine family of stimulants. Therapeutically, theophylline is sometimes used in the treatment of congestive heart failure, hyperactivity in children, and as a bronchial dilator in the treatment of asthma. Although caffeine is considered to be more potent, theophylline in very high doses (500-750 mg) can have potentially dangerous effects on the central nervous system, including convulsions or seizures. An average 5 ounce cup of tea contains about 1 mg of theophylline and 50 mg of caffeine.

How much caffeine is in soft drinks?

Soft drinks have become the favorite caffeine containing beverage in the United States: 12 oz. can of soft drink may contain 30-72 mg of caffeine. Less than 5% of this caffeine is from the kola nut; manufacturers add the other 95%, using the extract obtained from the decaffeination process. The level of caffeine found in a particular brand is consistent from can to can because of strict manufacturing controls. Only those soft drinks containing caffeine will show it as an ingredient on the product label. To compare brand names, see the chart below. You may be surprised at how many soft drinks contain caffeine and the amount in your favorite beverage.

How much caffeine is in soft drinks?

[Data obtained from the National Soft Drink Association]

Why is caffeine added to soda?

American society has a history of adding substances to food and drink that are addictive in order to sell more. Consider the jingle, "You can't eat just one." If you were selling these products don't you think you would do research to find out which additive/preservative is most addicting? This was the premise behind adding cocaine to coca-cola when it first came out. Of course today cocaine can no longer be used as an additive and caffeine has been substituted instead. Only after medical research shows evidence of a problem with a drug do manufacturers look for alternatives.

Which over-the-counter medications contain caffeine?

Caffeine has been used as a medication throughout history. In the 1500's, Europeans used caffeinated beverages to treat headaches, vertigo, lethargy, coughs, and even prevent plague and other illnesses. In more recent years caffeine has been used to relieve fatigue, increase motor skills such as typing or driving a car, relieve migraine headaches in combination with other drugs; and as a possible treatment for hyperactive children, though most studies have failed to confirm its usefulness in this case.

In the U.S., the Food and Drug Administration regulates caffeine's use in over- the-counter medications and requires manufacturers to list caffeine as an active ingredient on each product's label. The chart below shows the widely varying amounts of caffeine in several commonly used preparations. Consumers may want to carefully read the label of any over-the-counter preparation they are planning to use, as this caffeine added to the amount regularly consumed, in soda drinks or coffee, could contribute to caffeine overdose and unwanted side effects.

[Source: FDA's Center for Drugs and Biologics]

Does chocolate contain other stimulants beside caffeine?

Cocoa derived from the seeds of the Theobroma cocoa plant (or cocoa beans) is used in making chocolate milk, hot cocoa, and various confections. It contains small amounts of caffeine, plus large amounts of theobromine, another alkaloid in the xanthine family. Theobromine is classified as a mild central nervous system stimulant and has physiological effects similar to those of caffeine, but much weaker. The average cup of hot cocoa contains about 10 mg of caffeine but over 200 mg of theobromine. A 3 1/2 ounce chocolate bar contains approximately 12 mg of caffeine and 155 mg of theobromine.