For people with arrhythmia (irregularity of heartbeat), coffee drinking should be approved by a physician, because heavy doses of caffeine can alter heart rhythms. Those with high blood pressure should also consult their doctors because caffeine might raise that pressure. Several studies on laboratory animals have found evidence that caffeine can elevate the level of free fatty acids, lipids and cholesterol in the blood. But most of the major studies find little or no link between heart disease and coffee drinking .
Does caffeine cause cancer? In l981 the New England Journal of Medicine published a study by Dr. Brian Mac Mahon and colleagues at the Harvard School of Public Health. It concluded that drinking one to two cups of coffee daily doubled-and five cups a day tripled-a person's risk of getting cancer of the pancreas, the fourth largest cause of cancer deaths. Four eminent scientists, responding in the Journal of the American Medical Association, were harshly critical of Mac Mahon's study.
While scientists continue to study the effects of regular coffee consumption on human health, they are also examining the potential dangers of drinking decaffeinated coffee. In 1982, one out of seven Americans had switched to decaffeinated coffee (20years ago only one in 25 used the product). To remove caffeine from coffee beans, processors use solvents. Until 1975 the solvent in widespread use was trichloroethylene, replaced when the FDA threatened to ban it as a carcinogen. Since then companies have removed 97 percent of coffee's caffeine with methylenechloride. This solvent is applied to coffee beans, then rinsed away, but some researchers have been concerned that a potentially dangerous residue remains in the coffee. The National Coffee Association agrees that a trace residue lingers, but its scientists estimate that a consumer would have to drink 25 million cups of decaffeinated coffee a day to suffer ill effects from it.
One of the world's preeminent caffeine researchers presents what may be the final verdict on caffeine. When all the evidence is weighed, he has written, only pregnant women, and those with some special health problems such as arrhythmia, seem even remotely at risk from heavy consumption of regular coffee. For everybody else, since the risks are negligible or nonexistent, the risk-benefit evaluation is not difficult to make: caffeine can be acquitted.