Drinking Too Much Water Can Kill You

MELBOURNE:
Study Says `8 Glasses A Day’ Mantra A Myth, One Should Drink By Thirst.
Drinking too much water may cause potentially fatal water intoxication, claims a new study which has, for the first time, identified the mechanism that regulates fluid intake in the human body and stops us from over-drinking.
The study, led by researchers from Monash University in Australia, challenges the popular idea that we should drink eight glasses of water a day for good health.
It showed that a `swallowing inhibition’ is activated by the brain after excess liquid is consumed, helping maintain tightly calibrated volumes of water in the body .
“If we just do what our body demands us to we will probably get it right -just drink according to thirst rather than an elaborate schedule,“ said Michael Farrell, associate professor at Monash.
The researchers asked participants to rate the amount of effort required to swallow water under two conditions; following exercise, when they were thirsty , and after they were persuaded to drink an excess amount of water.
The results showed a three-fold increase in effort when over-drinking. “Here, for the first time, we found effortful swallowing after drinking excess water, which meant they (participants) were having to overcome some sort of resistance.This was compatible with our notion that the swallowing reflex becomes inhibited once enough water has been drunk,“ Farrell said.
Researchers used functional
magnetic resonance imaging (fMRI) to measure activity in various parts of the brain, focusing on the brief period just before swallowing. The fMRI showed the right prefrontal areas of the brain were much more active when participants were trying to swallow with effort, suggesting that the frontal cortex steps in to override the swallowing inhibition. Drinking too much water puts the body in danger of water intoxication or hyponatremia, when vital levels of sodium in the blood become abnormally low, potentially causing symptoms ranging from lethargy and nausea to convulsions and coma.