Short-Term Effects

The short-term effects of caffeine are well agreed upon and widely documented. A good summary appears in The Pharmacological Basis of Therapeutics by Dr. J. Murdoch Ritchie. On the positive side, caffeine produces "a more rapid and clearer flow of thought," and allays "drowsiness and fatigue. After taking caffeine one is capable of greater sustained intellectual effort and a more perfect association of ideas. There is also a keener appreciation of sensory stimuli, and motor activity is increased; typists, for example, work faster and with fewer errors." Such effects are produced by caffeine equivalent to the amount contained in one to two cups of coffee. According to Dr. Ritchie the same dosage stimulates the body in a variety of other ways: heart rate increases, blood vessels dilate; movement of fluid and solid wastes through the body is promoted. All this adds up to the beloved "lift." On the negative side are the medical descriptions of the familiar "coffee nerves." The heavy coffee drinker may suffer from chronic anxiety, a sort of "coffee come-down," and may be restless and irritable. Insomnia and even twitching muscles and diarrhea may be among the effects. Very large doses of caffeine, the equivalent of about ten cups of strong coffee drunk in a row, produce toxic effects: vomiting, fever, chills, and mental confusion. In enormous doses caffeine is, quite literally, deadly. The lethal dose of caffeine in humans is estimated at about ten grams, or the equivalent of consuming 100 cups of coffee in one sitting.

Caffeine Content

The average cup of American-style coffee contains about 100 to 150 milligrams of caffeine; a properly prepared demitasse or single serving of espresso 80 to 120 milligrams. The average cup of tea delivers about 40 milligrams; the average chocolate bar about 20 to 60. A 12-ounce bottle of cola drink contains 40 to 60 milligrams, about as half as much as a cup of coffee.

Coffee and Health

An Introduction Although coffee first appeared in human culture as a medicine, the kind we now patronize as "herbal," the modern medical establishment has viewed coffee over the years with suspicion. So much so that coffee has become one of the most intensely scrutinized of modern foods and beverages. Why has the medical establishment chosen to focus so much attention on coffee in particular? Why not on scores of other foods, from white mushrooms to black pepper to spinach, all of which have been accused of promoting various diseases? Perhaps because coffee is such an appealing dietary scapegoat. Since it has no nutritive value and makes us feel good for no reason, coffee may end up higher on the medical hit list than other foods or beverages that may offer equal or greater grounds for suspicion, but are more nourishing and less fun. For now, however, the coffee lover can rest easy, or at least sip easy. Despite over twenty-five years of intensive study, medical science has yet to prove any definite connection between moderate caffeine or coffee consumption and disease or birth defects. For every study that tentatively suggests a relationship between moderate coffee drinking and some disease, or between moderate coffee drinking during pregnancy and a pattern of birth defects, other studies--usually involving larger test populations or more stringent controls--are published that contradict the earlier, critical studies. It is safe to say that the medical profession is far away from slapping coffee with the kind of warning labels that decorate wine and beer bottles. To be cautious, if you are pregnant or have certain health conditions, you should bring your coffee consumption to the attention of your physician, even if it is a moderate habit. Aside from pregnancy, health conditions that merit examining your coffee drinking include benign breast lumps, high chloresterol, heart disease, osteoporosis, and some digestive complaints. Again, nothing has been proven against moderate coffee consumption in any of these situations, but overall results are ambiguous, some physicians may disagree with certain studies that exonerate caffeine, and new studies may have appeared that complicate the matter.