Bottlemania - Elizabeth Royte [14]
Mike, a consumer-relations representative, writes me back: “i am unfamiliar with the advertisement you are speaking of. however, our advertising is meant to be taken light heartedly. our goal is to communicate our products in a fun, irreverent and humorous way[.] if you have any questions or if I can be of further assistance, please don’t hesitate to contact me. thank you again, and remember to drink better water!”
And drink a lot of it, Mike forgets to say. All the bottlers are now advising us to consume eight eight-ounce glasses of water each day. Their ads remind us the adult human body is 50–65 percent water (babies are even soggier, at 75 percent), and that dehydration can lead to seizures, then brain damage, then death. It sounds pretty serious. But is it true?
Though the maxim has become accepted wisdom, eight a day has never been scientifically proved. In fact, says Heinz Valtin, a retired Dartmouth Medical School kidney specialist, it makes little sense. Valtin spent a lot of time searching for the definitive source of the rule but discovered only that the Food and Nutrition Board of the National Research Council recommended adults drink approximately “1 milliliter of water for each calorie of food,” which translates to roughly two to two and a half quarts per day (or sixty-four to eighty ounces). The report states, in its next sentence, that “most of this quantity is contained in prepared foods,” though Valtin suspects few readers got that far. Digging further, the physiologist analyzed published surveys of healthy populations and found that most people weren’t drinking that much. An enormous amount of scientific literature shows how well the body maintains water balance, he noted. “The body can’t store water. If you have more than you need, you just pee it away.”
Now, Valtin says, he’s tired of trying to prove a negative. “I would argue further that for the time being the burden of proof that everyone needs eight by eight should fall on those who persist in advocating the high fluid intake without, apparently, citing any scientific support.” Not only does food count for fluid intake (most of a cooked noodle’s or rice grain’s weight is water), medical scientists argue, so do caffeinated beverages and, in moderation, beer. Let thirst be your guide, says Dr. Simeon Margolis, professor of medicine and biological chemistry at the Johns Hopkins School of Medicine. (Unless you’re elderly, says Roberta Anding, a clinical dietitian in adolescent and sports medicine at Baylor Medical College. “Thirst is one of the poorest-tuned defense mechanisms we have. The older you get, the less reliable that is. And athletes, of course, need even more than eight eight-ounce glasses a day.”)
Drinking too much water can, though, be dangerous. In January of 2007, a Sacramento County, California, woman trying to win a Nintendo Wii on a radio program drank almost two gallons of Crystal Geyser without a bathroom break. She left the radio station with a headache, didn’t win the Nintendo, and died that afternoon in her home. The condition, called hyponatremia but more frequently referred to as “water intoxication,” causes blood levels of minerals and sodium to plummet. It can lead to brain swelling, seizures, coma, and then death. A college student died after a similar stunt, in 2005, as have athletes and teenagers after ingesting ecstasy, which brings on a powerful thirst.
I’m so caught up in this question of proper hydration that I start wondering if my daughter, Lucy, will do better on spelling tests if her brain—which is, like everyone’s, 75 percent water—has more of it. I am convinced