Credits: Roberto Verzo
Science

Do we really need 8 glasses of water a day?

By Kirby Evans

The government recommendations and the NHS-endorsed ‘eat well guide’ are consistent in their advice that we should be drinking 6-8 glasses (around 2 litres) of water a day.

This is not new information. However, these guidelines have been the topic of many a discussion in recent months and scientists are challenging them regularly.

A recent study carried out by Monash University found that, in simple terms, our bodies will try to stop us from over-drinking. It found that a ‘swallowing inhibition’ is activated following the consumption of excess liquid, although once this process has been activated, FMRI scans show that the brain (frontal cortex) steps in to override the swallowing inhibition so drinking can occur. Essentially – our body no longer needs or wants more water, yet it finds a way to allow for both of these opposing processes to both occur.

This phenomenon seems odd when we consider that drinking too much water puts the body in danger of water intoxication or hyponatremia; when vital levels of sodium in the blood become so low that they can cause symptoms ranging from lethargy and nausea to convulsions and even induce comas.

So is the 8 glass rule in fact a lie?
Is it another example of Pseudoscience[1]?
Are water companies brainwashing us into purchasing their products?

Well, no.

Consider this: The NHS also advise that we should be consuming 5 portions of fruit and vegetables each day. Other countries recommend anything up to 13 portions of vegetables and 4 portions of fruit (Japan, in case you were wondering). So why in the UK is the suggested amount so low? It transpires that a balance has to be found between what is ideal and what is feasible. Our diets, our culture and our day to day time-constrained lives do not comfortably allow for so much green goodness; and so 5 it is.

Similarly, its 6-8 glasses of water. 8 is ideal but 6 will suffice. If on one day you were to only drink 3, you are not going to die from dehydration. But on the flip side, you won’t find yourself in a coma from consuming 9. This being said, water is vital to our survival, and below are 4 of the key functions it has within our body:

1. Cell function

2. Chemical and metabolic reactions (breaking down food)

3. Transport of nutrients and removal of waste (as blood and urine)

4. Body temperature regulation (think about sweat)

Further to this, the study previously mentioned fails to explain that the water consumed was done so in a short window of time. The idea is that we spread our 2 litres out over the course of the day, to avoid water loading and consequently a ‘swallowing inhibition’. If you do experience this, maybe put the water bottle down.

The study also limited its water intake to glasses. It fails to recognise that water is found in food, tea, coffee, milk, and even alcohol. So, as much as I recommend you not to take this article as certified health advice (by no means am I qualified) I would suggest you take the guidelines with a pinch of salt, because ultimately our bodies know what we need, and if you listen to its signals, you won’t go far wrong.


[1] NB: Ear candles are a prime example of pseudoscience

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