What's That Stuff?s are pretty fun to write—you get to look at an everyday item in your pantry, on the road, or in your hair in a completely different light. I just finished my first What’s That Stuff? article, about the history and production of instant coffee. It is freely available here. It does not, however, include any information about the health benefits of coffee.
Although the common idea is that coffee causes dehydration, says Roger Cook, director of the Coffee Science Information Centre, some studies suggest that coffee is an important source of fluid in the diet and that coffee’s caffeine is no more of a diuretic than water is—it increases the frequency of urination, but not the volume of fluid that is expelled over a period of time.
Thousands of studies have also been published proposing that coffee provides alertness, delays degenerative brain diseases such as Alzheimer’s, and slows down cognitive decline in the elderly. Many studies use fresh-brewed coffee, but don’t rule out instant coffee in offering such health benefits, Cook says. “The physiological effects of coffee are primarily due to the caffeine content and not to the manufacturing or brewing method,” he adds.
In a study looking at sleep-related accidents, researchers compared 30-minute naps, caffeinated coffee, and decaffeinated coffee to see how caffeine affects alertness during nighttime driving (Ann. Internal Med. 2006, 144, 785). The coffee these researchers provided their subjects with was—you guessed it—instant! Nestlé instant coffee packets were used for both the caffeinated (4.25% caffeine) and decaffeinated (0.03% caffeine) coffees. The result? A 30-minute nap at 1 AM or a cup of coffee with 200 mg of caffeine has pretty much the same alertness-boosting effect for nighttime driving, but decaffeinated coffee will leave you swerving in the road.
I wondered, however, if the beneficial effects of caffeine cross over to sodas, teas, and other caffeinated wonders. One study looking at Chinese adults suggests this is true for tea (Am. J. Clin. Nutr.2008,88, 224), but, personally, I think that sodas are almost like cigarettes, which can also contain caffeine. Malic acid, one of the thousands of compounds used in cigarettes, can help boost immunity and metabolism. But in combination with the multitude of other ingredients, the total health benefit is probably outweighed by the negatives. That goes for what you put in your coffee, too—these studies don’t include added cream or sugar!