The study that was made by multiple institutes led by Monash University has revealed the information about regular fluid intake, its mechanisms, and what stops us from drinking too much, an action that could cause water intoxication, which could end up being fatal. This particular study is making a statement, trying to challenge the mandatory idea that we should drink eight glasses of water per day to remain healthy.
Study shows that, after we drinking enough water to satisfy our body's needs, the brain makes an effect which is called "swallowing inhibition" to prevent us from drinking more.
Associate Professor Michael Farrell from the Monash Biomedicine Discovery Institute said:
"If we just do what our body demands us to we'll probably get it right - just drink according to thirst rather than an elaborate schedule,"
Witch this knowledge, researchers took the next step. They've made a test where they tested the amount of effort needed to swallow the water. First condition was when the participants were thirsty, and after they were asked to drink more water than they could. Result was that the over-drinking takes three times the usual effort.
"Here for the first time we found effort-full swallowing after drinking excess water which meant they were having to overcome some sort of resistance," Associate Professor Farrell said.
"This was compatible with our notion that the swallowing reflex becomes inhibited once enough water has been drunk."
Associate Professor Farrell used functional magnetic resonance imaging (fMRI) to measure activity in various parts of the brain, with the focus on the short period before swallowing. The tests showed that some areas of the brain were much more active when there was an effort to swallow more, showing that we could override the swallowing inhibition, thus allowing us to drink the water.
"There have been cases when athletes in marathons were told to load up with water and died, in certain circumstances, because they slavishly followed these recommendations and drank far in excess of need."
When we drink too much water, the body is in danger of hyponatremia or water intoxication, because the level of sodium in blood becomes low thus causing symptoms from lethargy to coma.
Associate Professor Farrell said that old people should increase of the amount of water they drink, because the study showed their intake is below the needed level.
The study, 'Overdrinking results in the emergence of swallowing inhibition: an fMRI study,' is published online in the Proceedings of the National Academy of Sciences.
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