But some believe it's better for them than regular coffee -- even though coffee has been cleared of nearly all health charges, and may actually be beneficial.
Is decaf somehow healthier than regular coffee? Or does the decaffeination process itself represent a health risk? On the other hand, many Americans are drinking tea because they've heard how healthy it is. If they drink decaf tea, they may wonder, do they get the health benefits?
Here are answers to these and other questions.
How much caffeine does decaf contain?
It must have at least 97% of the caffeine removed. That leaves about 5 milligrams, compared to the 100 to 150 milligrams in 6 ounces of brewed coffee. Tea starts with much less caffeine, so most decaf tea has even less caffeine than decaf coffee.
How is coffee or tea decaffeinated?
There are three methods to extract the caffeine: using organic chemical solvents (methylene chloride or ethyl acetate), carbon dioxide, or the water method (also known as the Swiss Water method). Since ethyl acetate is derived from fruit, coffee de-caffeinated via this solvent is sometimes described as "natural" decaf. Some coffee or tea processors use different methods for their various products.
Is one type of decaf preferable?
No. Over the years there have been worries about decaf processed with methylene chloride because studies had found that this chemical caused cancer when inhaled by lab animals (which is why it was banned in hair sprays). But there was no carcinogenic effect when the animals drank the chemical.
In any case, the residue in decaf is virtually nil, and there's no evidence of any danger for humans drinking decaf. The FDA has approved the compound for use in decaffeination.
Many companies, including Starbucks (except for its decaf mocha java), use methylene chloride because consumers tend to prefer the taste compared to, say, water-filtered decaf, which usually tastes blander.
Does regular coffee pose any health risks?
Coffee has been blamed for causing many ailments, but in nearly every instance it has been declared not guilty, as we have reported over the years.
It was linked to heart disease and pancreatic cancer -- but then exonerated. Some researchers still worry that coffee drinking may promote hypertension; most studies, however, have found no such effect. A few studies have suggested that large quantities of coffee (regular or decaf) can boost blood cholesterol slightly, but most research has found no increase in cholesterol or cardiovascular risk
One exception: drinking five or more cups of unfiltered coffee, brewed in a French press (a pot with a plunger), raises cholesterol. The great majority of Americans and Canadians, however, drink filtered coffee.
Caffeine actually has potential benefits. Besides boosting alertness, it has an analgesic effect, which is why it is added to some pain relievers. Several studies also suggest it helps prevent Parkinson's disease.
A Finnish study in the New England Journal of Medicine in March found that coffee may reduce the risk of Type 2 diabetes. And there's preliminary evidence suggesting it may help against gallstones and dental cavities.
What about decaf: does it pose any risks?
Though decaf has been less studied than regular coffee, it too has been the focus of several health scares that have so far not panned out. For instance, a recent study of women in Iowa found that those drinking four or more cups a day of decaf had an elevated risk of rheumatoid arthritis, but a more recent study from Harvard found no such link.
Decaf can, however, have some of the same effects on the body as regular coffee. It too can cause heartburn or irritate stomach ulcers in susceptible people. And oddly enough, even without the caffeine, it too can stimulate the nervous system and briefly boost blood pressure in those unaccustomed to coffee, according to Swiss researchers. But coffee, decaf or regular, does not cause hypertension.
Is decaffeinated tea as healthful as regular?
No one knows. The studies suggesting health benefits have looked at people who drink a lot of regular tea, not decaf. The benefits apparently come from antioxidant compounds called flavonoids. Decaf tea generally contains less of these, though flavonoid content varies widely among teas, so it is hard to predict.
The levels also depend on how the tea was processed. Moreover, not all types of flavonoids are lower in decaf tea, and it's not known which ones are most important.
A few studies suggest that decaffeinated teas do have potential anti-cancer effects. For instance, one study found that smokers who drank four cups of decaffeinated green tea daily for four months had significantly reduced DNA damage, as shown by urine tests. Another study gauged the total antioxidant capacity of various teas and found that some decafs rank higher than some regular teas.
On the horizon: Coffee plants are now being genetically engineered to have 70% less caffeine. But it will take another four to five years for the plants to mature and produce beans. And it's not known whether coffee from these beans will taste better or worse than today's decaf.
UC Berkeley Wellness Letter, May 2004
Published 12 times a year, The University of California, Berkeley Wellness Letter is the only health letter to be top-rated by Money magazine and U.S. News & World Report as well as the Baltimore Sun and the Washington Post. To subscribe to the printed version click here.