There is a recent study that challenges the long-standing idea that it is “mandatory” for our health to drink at least eight glasses of water every day. Associate Professor Michael Farrell of the Monash University Department of Medical Imaging and Radiation Sciences, of the Monash Biomedicine Discovery Institute was the overseer for the work done by PhD student Pascal Saker, at the University of Melbourne. This was also part of a collaboration with the University of Melbourne, the Florey Institute of Neuroscience and Mental Health, and the Baker IDI and Diabetes Heart Institute.
Many who advocate drinking eight glasses or more of water every day don’t seem to realize that over-drinking can actually cause water intoxication that could potentially be fatal. The researchers state that we are fortunate that we have a mechanism to regulate fluid intake in our human body that normally keeps us from over-drinking. The study showed for the first time that the brain activates a ‘swallowing inhibition’ when excess liquid is consumed.
Participants in the study had to rate the amount of effort that was required to swallow water following exercise when they were thirsty, and then later when they were persuaded to drink an excessive amount of water. There was a three-fold increase in the swallowing effort after over-drinking, which validated that the swallowing reflex is inhibited when enough water has been consumed.
Functional magnetic resonance imaging (fMRI) was used to record the activity in different areas of the brain that focused on the short period that occurs just before swallowing. The right prefrontal areas were made more active when the participants attempted to swallow with a great effort, meaning that the frontal cortex steps in to override the swallowing inhibition, in order to avoid water intoxication. Intoxication occurs when the vital levels of sodium in the blood become abnormally low, which can potentially cause symptoms ranging from lethargy and nausea to convulsions and coma. Farrell recounted that there have been times when athletes running in marathons were advised to fill up with water and then died, because they followed those incorrect recommendations and drank far in excess of their actual need.
Associate Professor Farrell advocates going by what our bodies demand, stating we should just drink according to our thirst, not a deliberate schedule. We should trust in our ‘swallowing inhibition’ that the brain activates, if excess liquid is consumed. This helps maintain tightly calibrated volumes of water in our bodies.
