Several years ago, a 28-year-old California woman died after competing in a radio station’s on-air water-drinking contest. After downing some six liters of water in three hours in the “Hold Your Wee for a Wii” (Nintendo game console) contest, Jennifer Strange vomited, went home with a splitting headache, and died from so-called water intoxication.In 2005 a fraternity hazing at California State University, Chico, left a 21-year-old man dead after he was forced to drink excessive amounts of water between rounds of push-ups in a cold basement. Club-goers taking MDMA (“ecstasy”) have died after consuming copious amounts of water trying to rehydrate following long nights of dancing and sweating. Going overboard in attempts to rehydrate is also common among endurance athletes. A 2005 study in the New England Journal of Medicine found that close to one sixth of marathon runners develop some degree of hyponatremia, or dilution of the blood caused by drinking too much water.Severe cases of hyponatremia can lead to water intoxication, an illness whose symptoms include headache, fatigue, nausea, vomiting, frequent urination and mental disorientation and sometimes even death.
When a person drinks too much water in a short period of time, the kidneys cannot flush it out fast enough and the blood becomes waterlogged. Drawn to regions where the concentration of salt and other dissolved substances is higher, excess water leaves the blood and ultimately enters the cells, which swell like balloons to accommodate it. Brain cells however are tightly packaged and has almost zero room to expand and swell. Thus, drinking too much water can cause the entry of water into brain cells leading to brain swelling, which manifests as seizures, coma, respiratory arrest, brain stem herniation and death,” explains the chief of nephrology at Massachusetts General Hospital and Harvard Medical School.
Where did people get the idea that guzzling enormous quantities of water is healthful? A few years ago Heinz Valtin, a kidney specialist from Dartmouth Medical School, concluded that no scientific studies support the “8 cups of water a day” dictum. In fact, drinking this much or more “could be harmful, both in precipitating potentially dangerous hyponatremia and exposure to pollutants, and since he published his findings, Valtin says, “not a single scientific report published in a peer-reviewed publication has proven the contrary.”So how do we know how much water to drink? Apparently there is some science behind it. According to Verbalis: While exercising, “you should balance what you’re drinking with what you’re sweating,” but measuring sweat output is not easy. When in doubt simply follow Verbalis’s advice, “drink to your thirst. It’s the best indicator.”