What if I can't drink eight glasses of water a day? - page 2
This is flat wrong. Caffeine does cause a loss of water, but only a fraction of what you're adding by drinking the beverage. In people who don't regularly consume caffeine, for example, researchers say that a cup of java actually adds about two-thirds the amount of hydrating fluid that's in a cup of water. That is to say, one cup of coffee equals about two-thirds a cup of water--if you're not a regular caffeine drinker. Regular coffee and tea drinkers become accustomed to caffeine and lose little if any, fluid. In a study published in the October issue of the Journal of the American College of Nutrition, researchers at the Center for Human Nutrition in Omaha measured how different combinations of water, coffee, and caffeinated sodas affected the hydration status of 18 healthy adults who drink caffeinated beverages routinely.
"We found no significant differences at all," says nutritionist Ann Grandjean, the study's lead author. "The purpose of the study was to find out if caffeine is dehydrating in healthy people who are drinking normal amounts of it. It is not." The same goes for tea, juice, milk, and caffeinated sodas: One glass provides about the same amount of hydrating fluid as a glass of water. The only common drinks that produce a net loss of fluids are those containing alcohol--and usually, it takes more than one of those to cause noticeable dehydration, doctors say.
Do the Math: We're Drinking Plenty.
Now, take a close look at a survey released this May by the International Bottled Water Assn. Based on interviews with 2,818 adults in 14 U.S. cities, the association concluded that "although an overwhelming majority of Americans know that drinking water enhances health, most don't drink as much per day as they should." Yet, according to the association's own numbers, Americans say they drink an average of 6.1 glasses of water, 3.7 servings of soda or sports drinks, 3.2 of coffee and tea, 1.9 of juice, 1.7 of milk, and one alcoholic drink each day.
All told, after subtracting the alcoholic drink, that's a sopping 15 glasses of hydrating fluids, well above the already exaggerated "minimum." And it doesn't even include the three or four glasses contained in solid food. What do we do with all this excess water? Ask any water junkie who's tried to sit through a movie lately: We run to the bathroom. For some people, drinking plenty of water is a very good idea. As we age, for example, many of us grow less sensitive to losses of body water and don't drink when we should. Developing a water habit is a good precaution against dehydration.
In addition, researchers have good evidence that people who develop kidney stones can lower their risk of further problems by drinking more fluids. "Those are the only patients we would tell to drink more water," says Alpern. But there are also people for whom guzzling water is dangerous. According to Dr. Gary Robertson, who studies water metabolism at Northwestern University Medical School in Chicago, these are patients whose bodies have trouble eliminating fluids--for example, those with diabetes who are taking the anti-diuretic hormone, or ADH, which prevents the body from losing water. "The excess water cannot be excreted," he says, "and the result is water intoxication, which produces symptoms ranging from a mild headache to confusion, coma, seizures, and occasionally even death."
