[H.sub.2]O myth all wet. (updates).

Fashion magazines, diet gurus and grandmothers all recommend drinking at least eight 8-ounce glasses of water a day. But according to a noted Dartmouth Medical School researcher, this age-old "wisdom" is the nutritional equivalent of an urban legend with no basis in fact.

Heinz Valtin, MD, kidney specialist and professor emeritus of physiology at Dartmouth, in Hanover, New Hampshire, conducted a comprehensive review of all related scientific studies and found no evidence to support the "water intake recommendation," as it's also known. Food and fluid intake surveys, conducted on thousands of adults of both genders who have varying intakes of both water and fluids, found that those surveyed were healthy and not overtly ill. Despite the large number of people seen perpetually sipping from water bottles, such a large amount of water may be unnecessary after all, the results suggest.

These conclusions apply to healthy adults in a temperate climate, leading a largely sedentary existence. Valtin says that consumption of eight glasses of water is indeed called for under special circumstances such as strenuous physical work or exercise, especially in hot climates.

Excess water consumption can in fact be dangerous, says Valtin. It can cause water intoxication, which can lead to mental confusion, seizures and even death. Water intoxication occurs when the kidneys' excretion of water as urine cannot keep pace with fluid intake, a condition being reported with increasing frequency in endurance athletes, military recruits, people taking recreational drugs and certain types of patients.

Valtin has a theory about how the "eight glasses per day" myth came to be. A 1945 Food and Nutrition Board report by the Institute of Medicine stated that the body ...