WHY YOU’RE DRINKING TOO MUCH WATER

Experts Are Questioning The Long-Touted Rule Of Eight Glasses a Day

by Betsy Mckay

    Cooling off after their workouts in Smyrna, Ga., Lisa Mozer and Bobbie Hall are discussing how much water they should drink each day.

    “Eight glasses,” declares Ms. Mozer, a 42-year old meteorologist, gulping a bottle of Aquafina. “All the nitrition stuff we read says that.”

    That “nutrition stuff” may be wrong. Everyone from women’s magazines to Colon Health Network and the Georgia Rural Water Journal extols the virtues of drinking at least eight, eight ounce glasses of water a day. Bottled water makers heavily market their products based on this theory - so commonly held that nutritionists refer to it simply as “eight-by-eight.” The industry’s trade group even has a “hydration calculator” on its Web site for people to determine whether they need even more than that.

    But a growing number of health experts say the advice may not hold water.

    Researchers who have tried to pinpoint the origin of the eight-by-eight rule have come up dry. “The idea is being promoted terrifically by the bottled-water industry, but I have found no scientific evidence that supports the claim,” says Heinz Valtin, a kidney specialist at Dartmouth Medical School. Later this year, the American Journal of physiology is expected to publish the results of nine months of research by Dr. Valtin that led to that conclusion.

    The National Academy of Sciences, one of the perpetrators of the eight-by-eight wisdom, recently formed a panel to develop new guidelines. They are due out in March. “We need to look at it again,” concedes Allison Yates, director of the Academy’s Food and Nutrition Board .

    The upshot: We may not be as dehydrated as bottled water makers would have us believe. The only studies researchers have found that bolster the eight-by-eight rule were performed on soldiers at high altitude, hospitalised patients, and others in “nontypical environments,” says Ann Grandjean, a nutrition specialist at the University of Nebraska, and a consultant to the U.S. Olympic Committee. For the average American adult who rarely breaks sweat and works in a climate-controlled office, eight-by-eight may be more than enough.

Is Eight Glasses a Day Too Much?

    For most people, the consequences of drinking too much water are simply extras trips to the bathroom. But for a few, excessive amounts can be harmful, even fatal. Some diabetics and others take a high dose of an antidiuretic hormone to prevent the body from losing water. If such individuals consume too much liquid, they can develop “water intoxication”: the excess water can dilute sodium in the blood, causing a swelling of the cells that in extreme cases can lead to seizures and death.

    No one disputes that drinking plenty of water is a good idea. A study published this month in the American Journal of epidemiology, asserts that drinking water can help reduce the risk of fatal heart attacks.

Six glasses during a workout?

    But for bottled water makers, hydration translates into sales. On a website for its Dasani brand, Coca Cola Co. urges people who exercise to “consume at least 16 ounces of fluid [two glasses] before you start your activity and then five to eight ounces every 15 minutes, while you’re working out.” The lable of Zephyrhills, Nestlé SA water brand, urges consumers to “drink a 24-oz. Zephyrhills Brand Sport-Pack [three glasses] two hours before you exercise.” (The company says hydration tips are being phased out on packaging, in favour of graphics and wording that promotes it’s brand.)

    The International Bottled Water Association, which represents the $6.4 billion, bottled water industry in the U.S. has a hydration calculator on its Web site that recommends a 140 pound person drink 70 ounces, about 8 1/2 glasses, of water on a day in which he or she doesn’t exercise. An hour-long workout raises the recommended daily intake to 110 ounces – nearly 14 glasses. The association cites the National Academy of Sciences as well as hydration experts and various studies as the sources of its hydration tips.

    “Americans still aren’t drinking enough water,” says Stephen Kay, a spokesman for the bottled water association. While water isn’t the only source of hydration, it’s the healthiest, he argues. “It’s caffeine and calorie free.”

Try lettuce and watermelon.

    How much is enough actually depends on the individual, nutritionists say. People who exercise need more liquids than couch potatoes to help replenish the fluids they’ve lost. The average adult loses about 2 litres of fluid a day, but about half of that amount can be replaced through a healthy diet and the body’s own metabolism, nutritionists say. Lettuce is 98% water; other vegetables and fruits contain sizeable amounts of water, too. (Foods heavy in fat and oils contain the least.) Nutritionists are even questioning whether coffee and cola are dehydrating, as commonly thought.

    In fact, after much thought, nutritionists have come up with this guideline for determining hydration needs: drink enough so you don’t get thirsty.

Wall Street Journal May 23, 2002