Uncommon Grounds by Mark Pendergrast, 1999, Excerpts
Caffeine is the most widely taken psychoactive drug on earth, and coffee is its foremost delivery system. “Coffee causes an excessive state of brain-excitation which becomes manifest by a remarkable loquaciousness sometimes accompanied by accelerated association of ideas.” – Lewis Lewin, Phantastica: Narcotic and Stimulating Drugs, 1931.
Caffeine doesn’t keep us awake in a positive sense – it just blocks the natural mental brake, preventing adenosine from making us drowsy. Experts in fact don’t agree on much when it comes to coffee and caffeine intake, partly because individuals exhibit remarkably different reactions Some people are wired for hours with a mere sip; others can drink a double espresso right before falling into a sound sleep. Thus, every coffee lover should determine his or her level of comfortable consumption, preferably no more two or three cups a day.
Although some bugs and fungi adapt to any chemical, it is quite likely that plants contain caffeine because it affects the nervous system of would-be customers, discouraging them from eating it. Of course, that is precisely the attraction of the human animal.
Caffeine causes the heart to beat more rapidly, constricts some blood vessels, and causes certain muscles to contract more easily. People with high blood pressure, as well as those with insomnia and anxiety disorders, should consult their physician about their caffeine intake.
At the same time, however, it can relax the airways of the lungs and open other types of blood vessels. Caffeine can help those who suffer from asthma and is given to infants suffering from neonatal apnea [cessation of spontaneous breathing]. Some adults with allergies find that caffeine allays symptoms. It can mitigate the pain of migraine headaches though withdrawal causes other headaches. For those who need diuretic or laxative, coffee provides relief. Some studies even commend the drink’s use as an antidepressant to prevent suicide.
Caffeine has been shown to increase sperm motility, so it may prove useful in artificial insemination programs though others fear it may harm the sperm while speeding it on its way. Combined with analgesics such as aspirin, caffeine appears to help alleviate pain. It may have therapeutic potential for some cancers, though evidence is weak. While coffee often is accused of providing no nutrition, it provides minute traces of potassium magnesium and manganese. Because it raises the metabolic rate, it may help with dieting, but the effect is slight. Like Ritalin, caffeine has a paradoxical effect on hyperactive children with attention-deficit disorder: letting such children drink coffee seems to calm them down. Caffeine is a diuretic, and small amounts of calcium float away in the urine, leading to concern over possible bone loss.
Many doctors have expressed concern about pregnant and nursing women who drink coffee. Caffeine readily passes through the placental barrier to the fetus, and it turns breast milk into a kind of natural latte. Because premature infants lack the liver enzymes to break down caffeine, it stays in their systems much longer. Research has failed to prove that caffeine harms the fetus or breastfed infants, but recent studies appear to implicate caffeine in lower lightweights. By the time they are six months old, most children eliminate caffeine at the same rate as adults, with a bloodstream half-life of around five hours.
Surprisingly, there is little evidence that caffeine harms children, despite widespread belief that it stunts growth, ruins health, and so. Like adults, however, children are subjects to withdrawal symptoms – from soft drink derivation more frequently than from coffee.