The last 25 years has seen the growth of a cottage industry in the study of the health effects of drinking coffee. And no wonder - over 400 million cups a day are consumed throughout the world. But for decades health workers warned that the habit might be unsafe. Recent studies show the opposite is more likely to be the case.
Caffeine, one of the main ingredients in coffee, has long been known to be a mild stimulant. That can raise blood pressure, increase heart rate and produce the occasional irregular beat. But most researchers now believe the effect is mild and short-lived.
By contrast, the emerging data about the health benefits of coffee consumption are numerous and diverse.
There's strong evidence that coffee reduces the odds of developing colon cancer, but only at higher levels of consumption - four cups a day or more. That much intake may well outweigh the benefits.
But other benefits accrue even at moderate levels of coffee drinking.
Coffee, like wine, contains antioxidants that help prevent heart disease and certain cancers by removing cell-destroying oxygen radicals from the blood. Some studies say the concentration of antioxidants is greater than that found in cranberries, apples or tomatoes. Scientists, however, point to the many other valuable vitamins, minerals and fibers in fruits and vegetables.
Apart from the obvious contribution to mental alertness, Chinese studies strongly suggest that coffee can even help reduce the effects of Parkinson's disease.
American and Scandinavian studies both suggest that decaf and regular coffee help reduce the risk of type-2 diabetes. Good news for the Scandinavians who have the highest per capita consumption in the world.
There's some evidence that coffee may reduce the risk of developing kidney stones and gallstones. Other digestive system benefits have been seen, as well. Caffeine increases the secretion of stomach acid, which aids digestion.
Caffeine has been shown to reduce constriction of airways in asthma sufferers, with moderate consumption. In addition to the caffeine, coffee contains theophylline, a bronchodilator which helps the effect.
But those benefits, not surprisingly, come with risks.
Though mammalian sperm swim faster, longer and farther in fluids laced with coffee some studies link heavy coffee drinking with reduced fertility.
Increased coffee consumption has been associated with higher blood levels of homocysteine, recently shown to be a risk factor for coronary heart disease. Other studies show an increase in LDL-cholesterol (the 'harmful' kind). To what degree these factors actually contribute to heart attacks is a matter of debate.
Coffee contains cafestol, which is known to raise cholesterol levels, mainly in coffee made by the European method of boiling ground beans in water. Percolated or filtered coffee, favored by most Americans, however, removes it. Decaf coffee may be an exception.
Women who drink coffee lose more calcium and tend to have less dense bones than non-caffeine consumers. Those who drink four or more cups per day also have twice the risk of urinary incontinence.
All in all, though, most agree that the benefits - at least at moderate consumption levels - outweigh the risks. By the way, for those heavy drinkers looking for a substitute, colas contain one-third the amount of caffeine per ounce. But somehow drinking a Coke instead of a Latte doesn't seem worth the risk.
Decaf, good or bad?
Recently a variety of the coffee tree was discovered that naturally contains almost no caffeine. Until and unless that species finds its way into commercial production, we're left with the current methods for removing unwanted caffeine from coffee. But how do those methods affect the taste of our java?
Blind taste tests suggest that most people can't really tell the difference between decaf and regular, provided both kinds are processed properly and the cup brewed well. But, for those who can...
Among the methods for removing caffeine from coffee is treatment with hot water, followed by rinsing in methylene chloride.
Maybe you didn't know your coffee had already seen water before you got to it? In fact, several times. The berries are rinsed after picking to soften the outer fruit for removal, then rinsed again to help eliminate the remaining flesh.
And possibly you were unaware your grounds had taken a dip in the swimming pool before being served. (Ok, swimming pool water is really dilute hydrochloric acid, not methylene chloride. Never let a chemist stand between you and a good line.)
So, the taste difference is less likely to come from the presence or absence of caffeine as from any remaining processing chemicals and whether they removed flavor-producing components.
Chemical removal of the caffeine from green, unroasted beans starts by warming them in hot water or steam. That opens the bean's pores. Then the beans are rinsed in methylene chloride, which binds to the caffeine and is then flushed away.
Alternatively, the beans can be soaked for several hours in hot water, where the caffeine leaches out into the bath. The beans are removed and methylene chloride introduced to the bath. There it bonds with the caffeine, not the flavored components that have washed out of the bean. The beans are then soaked again where they reabsorb the flavor compounds.
An entirely different process, called the Swiss method, also soaks the beans in hot water for several hours, but no methylene chloride is used. Instead the caffeine is removed by filtering the water through activated charcoal. More or less pure carbon, the molecular structure of activated charcoal has been altered to provide a large surface area for other molecules to stick to.
The first method is less expensive and so is preferred by most manufacturers. And - no surprise - there are ongoing debates about whether it degrades the taste. As usual, quality control makes the largest difference. But, there are even techniques available to the individual for reducing caffeine intake.
Darker, less acidic, roasts already contain less caffeine as a consequence of the roasting process. And blends of decaf and regular are an option for those who simply must cut down.
As to the taste.... Well, as in any issue of taste, individual preferences generally swamp any objective chemical differences. Since caffeine has an inherently bitter taste, many can detect its presence or absence. Whether that makes decaf good or bad is, as they say, a matter of taste.