More ammunition in the war on people's health for the generals of the alternative army against the hordes of industrymen and their sycophants


Heath Effects, Reproductive Issues, and Short-Term Memory

Bennett Alan Weinberg, Esq. and Bonnie K. Bealer.

Mr. Weinberg is a medical and science writer.

Ms. Bealer is a researcher, writer and editor.


Editor's Note: The following is excerpted from the book The World of Caffeine: The Science and Culture of the World's Most Popular Bennett Alan Weinberg and Bonnie K. Bealer (Routledge, 2001).

What is it in man's devious make-up that makes him round on the seemingly more wholesome and pleasurable aspects of his environment and suspect them of being causes of his misfortunes? Whatever it is, stimulants of all kinds (and especially coffee and caffeine) maintain a position high on the list of suspicion, despite a continuing lack of real evidence of any hazard to health.

-Editorial, British Medical Journal, 1976, I:1031       

Coffee and caffeine have long been suspected of causing illnesses ranging from myocardial infarction, arrhythmias, hypertension, hyperlipidemia, gout, and anxiety, to fibrocystic breast disease, various cancers and birth defects, and osteoporosis. No other agent in the human environment has been as frequently associated with such a variety of chronic-degenerative, even malignant diseases.        

-Siegfried Heyden, "Coffee and Cardiovascular Disease," 1993       

Caffeine and, before caffeine was identified, coffee, tea, and chocolate, have been said to cause, exacerbate, palliate, or cure an enormous variety of diseases and have also been said to confer marvelous benefits, including increases in both intellectual and physical capacities. If, like the great majority of people in the world, you use caffeine regularly, you are faced with a complex, confusing, and often apparently contradictory cacophony of traditional and contemporary claims about its effects on human health. ... In the last half of the 20th century, an explosion of general medical knowledge and a large number of controlled experiments have shed scientific light on many of caffeine's effects. It has been often and truly said that caffeine is the most studied drug in history. Yet, because of its nearly universal use, the variety of its modes of consumption, its presence in and effects on nearly all bodily sy stems, and its occurrence in chemically complex foods and beverages, together with the complexity of the social and psychological factors that shape its use, caffeine may also be one of the least adequately understood. Despite tremendous scientific scrutiny, many central health questions about caffeine remain unanswered or even unaddressed.

Caffeine is like the air. You don't see it and usually hardly notice it, but it's there all the same, and it becomes part of you in a critical metabolic exchange that involves every cell in your body. Considering that the sensorium and biomass of the human race is virtually awash in caffeine, and has been besotted so for hundreds of years, and that an overwhelming majority of people in almost every nation, including young and old, healthy and infirm, rich and poor, has made the regular use of this psychoactive stimulant more popular than the habitual use of any other drug, what do we really know of caffeine? What do we know of what it is doing for us, doing to us, even doing to our unborn children? The answer, as should become clear after reviewing the very impressive record of studies presented in the following chapters and the appendices, and evaluating both the findings and limitations of this research, is, "not nearly as much as we need to know."

The great majority of babies begin life with detectable levels of caffeine in their blood. The lack of adequate information about caffeine's health effects is evident in the disagreements that exist among experts. For example, the FDA, as recently as the late 1980s, reaffirmed its earlier position that medical evidence demonstrated no adverse health consequences from caffeine in soft drinks, and the National Academy of Sciences' National Research Council and the U.S. Surgeon General's office agreed that no risk to health had been shown for moderate caffeine intake. In contrast, many researchers, adducing the complexity of caffeine's effects on the human body and the many aspects of these effects that have received limited research attention, argue that such a "clean bill of health" is not fully justified. ...       

Caffeine and Birth Defects       

The nature of caffeine's effects on birth abnormalities and fertility is probably the most urgent unresolved question that remains to be addressed by future researchers...

The consensus of the medical and scientific community is that, to avoid risk to the fetus, women ought to curtail caffeine use during pregnancy, although authorities differ about the nature or extent of the dangers of failing to do so. But the worrisome fact is that, despite this admonition, most women using caffeine continue throughout pregnancy, with an average intake among users of more than 200 mg a day. As a result, the great majority of babies begin life with detectable levels of the drug in their blood. Because fetal exposure to caffeine is so pervasive, any unfavorable effect on the health of the newborn, even one with a very low incidence, could mean tens of thousands of defective births a year in the United States alone. It is therefore critical to investigate the effect of caffeine exposure on the outcomes of pregnancy as exhaustively as possible.       

Two facts about caffeine metabolism increase concern over the harm that could be posed by maternal caffeine use.        

    First, caffeine metabolism dramatically slows during gestation. The metabolic rate drops progressively, falling to one-half normal during the second trimester, and to one-third normal during the third trimester, before returning to normal within the week following delivery. This means that caffeine that is ingested by the woman in the last few months of pregnancy will remain in her system three times longer than usual and, consequently, that the exposure of her unborn child to caffeine will last three times longer.        

Second, the livers of the fetus and newborn are unable to metabolize caffeine. Because of the incapacity of their hepatic enzyme systems, their livers cannot transform caffeine into its metabolites, so the drug lingers in their systems much longer than in either children or adults, until it is finally excreted, virtually unchanged, in the urine. One researcher found the mean elimination time in infants being treated for apnea with caffeine was one hundred hours, 15 times the adult average, and other scientists report a range up to about 350 hours in premature infants. These dramatic metabolic decrements, however, are short-lived. The infant's capacity to metabolize caffeine progressively increases in the first months of life until it reaches the adult level of three to seven hours by the eighth month, though full maturity of the metabolic pathways of caffeine may not be achieved until the end of the first year.    

Caffeine and Memory       

    In recent years, in addition to continuing studies of caffeine's effects on complex mental activities such as reasoning and learning, researchers have paid increasing attention to its effects on short-term memory. Overall, the results show that caffeine improves performance on tasks that require remembering small amounts of information and impairs or leaves unaffected performance on tasks requiring remembering a great deal. An example of a more demanding sort of memory task is a test in which subjects listen to or read long lists of words and are then asked to remember as many as possible. The experimenters note either no effect from caffeine or perhaps even a small impairment. Another way of conceptualizing these effects is provided by the Humphreys-Revelle model, according to which tasks that are primarily dependent on information processing, such as vigilance, simple arithmetic, or reaction time, are improved, because they make relatively small demands on short-term memory, while tasks with a high short-term memory component may be unaffected or adversely affected. Unfortunately, there is much ambiguity in the data that do exist about these effects. When weighing the conclusions of existing research, we would do well to remember a well-designed 1974 memory experiment by researcher V. E. Mitchell and his colleagues, the cautionary results of which were reminiscent of the title of Luigi Pirandello's play Right You Are, If You Think You Are, because they seem to demonstrate that performance was improved by caffeine when and only when the participants were told that they had ingested the drug.       

Caffeine may help you to stay awake, but it won't necessarily improve your intellectual skills. Nevertheless, millions of students use caffeine to fuel "all-nighters." Based on the available scientific evidence, how does this use of caffeine affect studying and test taking? Caffeine helps people to feel less drowsy and less fatigued, be better able to perform some manual or perfunctory tasks, such as typing or calculating, and, under certain circumstances, to be more capable of sustaining rapid thought and to remember more. However, some studies have found that caffeine does not significantly alter numerical reasoning, short-term memory of complex data, or verbal fluency. In other words, caffeine may help you to stay awake, but it won't necessarily improve your intellectual skills.       

Students depending on caffeine to extend their study time should also be aware of its possible adverse effects when taken in large quantities and be prepared for the crash after its stimulating powers subside. As Socrates suggested, the best guide for students is to know themselves: From a couple of Vivarin tablets, the sensitive may experience restlessness, anxiety, nausea, headache, tense muscles, and sleep disturbances, or a subsequent letdown, while others, from a much higher dose, might feel fine.

See also: An excerpt from Dr. Batmanghelidj's book, ABC's of Asthma, Allergies and Lupus