Eight Glasses Of Water A Day May Be Too Much

A study suggests that drinking water according to thirst is preferable to strictly following the ‘eight glasses a day’ rule.

AsianScientist (Oct. 18, 2016) – A multi-institute study has revealed a mechanism that regulates fluid intake in the human body and stops us from over-drinking, challenging the popular idea that we should drink eight glasses of water a day for health. Details were published in the Proceedings of the National Academy of Sciences.

Associate Professor Michael Farrell from the Monash Biomedicine Discovery Institute in Australia oversaw the work by University of Melbourne PhD student Mr. Pascal Saker, as part of a collaboration with several Australian institutes. Building on a previous study, the researchers asked participants to rate the amount of effort required to swallow water under two conditions; following exercise when they were thirsty and later after they were persuaded to drink an excess amount of water.

The study 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. Farrell 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 that the right prefrontal areas of the brain were much more active when participants were trying to swallow with much effort, suggesting that the frontal cortex steps in to override the swallowing inhibition, to allow drinking to occur according to the researchers’ instructions.

The results showed a three-fold increase in effort after over-drinking. Drinking too much water in the body puts it 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. Elderly people, however, often didn’t drink enough and should watch their intake of fluids, according to Farrell.

“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,” he added.

The article can be found at: Saker et al. (2016) Overdrinking, Swallowing Inhibition, and Regional Brain Responses Prior to Swallowing.


Source: Monash University; Photo: Pixabay.
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