Medical Edge Newspaper Column

Coffee: Neither a Panacea Nor a Source of Harm

March 4, 2007
Dear Mayo Clinic:
A friend of mine told me that decaffeinating coffee involves a chemical process that makes drinking the product bad for you. Is this true? Also, what is the current thinking on the health benefits of drinking coffee (either regular or decaf)? -- Rochester, Minn.

Answer:
Your friend is likely referring to a process no longer in use. In the past, coffee beans were decaffeinated using chemical solvents such as benzene, trichloroethylene, or methylene chloride, which turned out to be carcinogens or suspected carcinogens. There may never have been a cancer threat, because these compounds, being highly volatile, would evaporate later in the process. Still, people were concerned that even trace residues might potentially cause problems. Thus most companies have replaced the problematic chemicals with innocuous compounds, or have switched to alternative processes that involve water, carbon dioxide, or oxygen.

Given the large number of companies that now produce decaf, it is impossible to generalize. But I can say with some confidence that the major producers use decaffeination processes that are safe. So you can drink your decaf without concern about "bad actors" lingering in the brew from its manufacture.

As a matter of fact, drinking decaf has no known liabilities, unless you count the lost benefits of caffeine itself.

Nine out of 10 Americans consume some type of caffeine regularly, making it the most popular behavior-altering drug. It chases away fatigue, thereby improving alertness and energy level, and it can even improve one's disposition.

Coffee, whether decaf or regular, has actually been associated lately with a wide variety of health advantages. It is said to help protect people from constipation, type 2 diabetes, gall bladder disease, colorectal cancer, cardiovascular disease, alcohol-related cirrhosis and liver cancer, Alzheimer's disease, Parkinson's disease and dental caries. But I caution that no one should start drinking coffee, or up his or her daily dose, in anticipation of such benefits, as none of them has been proven, or even adequately explained.

Most claims derive from a small number of studies, which assessed coffee's effect under non-standardized conditions. There was little or no accounting for the type of coffee, its source, or how it was brewed. And there was no solid explanation for what ingredient of coffee -- a constellation of hundreds of chemicals -- was responsible for the alleged benefits. It could be the caffeine, or antioxidants, or a variety of other agents, or a subset of these chemicals acting together. Or it could be that many of these studies' conclusions are erroneous: the benefits, if valid, may have stemmed from other activities in the subjects' lives.

Nevertheless, coffee is a rich source of antioxidants -- naturally occurring food chemicals, such as polyphenols, that work to counter the effects of "free radicals," which cause inflammation and genetic mutation. Thus, if some of the health claims for coffee turn out to be true, its contained antioxidants may be responsible for the benefits. Meanwhile, caffeinated coffee has its risks. It can cause restlessness, anxiety, irritability, tremor, sleeplessness, headache, nausea, diarrhea or other gastrointestinal problems, and abnormal heart rhythms. In the past, coffee was suspected of contributing to pancreatic cancer, but after extensive scientific study the consensus is that there is no association between them.

You can avoid most of the documented side effects by drinking coffee in moderation -- say, one to three cups a day -- although some people are more sensitive to it. For instance, those who already suffer from hypertension or significant heart disease might do well to avoid it altogether. Even decaf, despite its name, is not completely caffeine-free. The standard is that beans contain no more than three percent of their original caffeine content.

Coffee, whether decaf or regular, may or may not be responsible for the many health benefits lately attributed to it; time will tell. At present, we can at least say that drinking coffee in moderation generally causes no harm.

-- Brent A. Bauer, M.D., Director, Complementary and Integrative Medicine Program, Mayo Clinic, Rochester, Minn.