Do We Really Need 8 Glasses of Water Daily?

Posted 11/15/2016 | By HealthCorps

Your body maintains a very delicate balance of water.  In order to do that, complicated bodily processes occur, with water shifting in and out of cells.  Your thirst mechanism will tend to kick in to nudge you to drink if you are just barely beginning to experience dehydration.  By the time you feel thirst; experts say you are likely already dehydrated.  But do we all need to drink precisely eight glasses of water daily?  That’s been the prevailing recommendation until this new study that just released, which suggests “eight” may not be the right answer for all of us.

The multi-institute study published online in the journal Proceedings of the National Academy of Sciences in the United States of America, built on data from a prior study on hydration, by asking subjects to rate the amount of effort it took to drink (a) after an exercise effort that made them thirsty and (b) after they were encouraged to drink excess water, despite feeling quite hydrated. The results of the study showed that a three-fold increased effort was needed when subjects perceived (physiologically) that they were “over-drinking.”

The researchers saw clear evidence of individuals needing to overcome some kind of resistance or natural push back when drinking excessive amounts of water.  This supported the prior study findings which suggested that a person’s swallowing reflex becomes inhibited or resistant once they’ve taken in sufficient water.  The findings suggest that we should drink according to thirst and not just follow a general recommended schedule.

The brain helps to maintain a tightly calibrated fluid balance in the body, by instigating a “swallowing inhibition” reflex after excess water is consumed or, when the body senses we are fluid-balanced.  If a person is forced to drink more than what they need, the mechanism appears to involve action by the prefrontal cortex of the brain, with it basically over-riding the natural impulse to shut down and not drink anymore.

People who drink too much water can end up with a condition called hyponatremia – when sodium levels in the body become dangerously diluted.  Sodium helps to regulate the amount of internal water, both in and around body cells.  When levels are disrupted, the person can develop symptoms including lethargy, decreased levels of consciousness, confusion and if severe, seizures and coma.  Athletes are at risk, especially during marathons, triathlons and other challenging and vigorous workouts, when they may misread how much liquid they actually need and over-correct, drinking too much fluid.  On the other hand, elderly people notoriously drink too little fluid because their thirst mechanism can diminish with aging.

This information is especially important for parents to consider.  Your child needs to be adequately hydrated, but you also need to be attuned to their reluctance to drink, which may indicate adequate hydration despite your assumption that they need more fluid.  Remember that one serving of juice is the recommended daily amount for young children, and the rest of a child’s fluids should be sourced from water, unsweetened tea and two servings of milk daily.

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