OVER DRINK­ING WA­TER CAN BE FATAL

Australian Natural Bodz - - Nutrition Knowledge Centre -

New study says drink wa­ter for thirst, rather than try­ing to get in 8 glasses, es­pe­cially as drink­ing too much wa­ter can cause wa­ter in­tox­i­ca­tion.

There is a new study that chal­lenges the long­stand­ing 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 over­drink­ing 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 over­drink­ing. 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 three­fold in­crease in the swal­low­ing ef­fort after over­drink­ing, 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.

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