There is no set RDA for the intake of water but it varies from person to person (some tend to retain eccess water, some don’t).
Water enters the body when we drink and is removed primarily in the urine and sweat.
The amount of water in the body is regulated to control the levels of certain compounds, such as salt, in the blood.
If you drink too much water, eventually the kidneys will not be able to work fast enough to remove sufficient amounts from the body, so the blood becomes more dilute with low salt concentrations.
According to a professor in clinical chemistry and forensic toxicology in Sheffield, drinking too much water lowers the concentration of salt in your blood so that it is lower than the concentration of salt in cells.
Water without salt in the body will cause swelling (apparently if you put salty water on onion skin the cells will shrink, if you put too much water on it the cells will swell).
The water then moves from diluting blood to the cells and organs. When the swelling gets to the brain the pressure increases in the skull and you may get a headache. When the brain is squeezed it compresses vital regions regulating functions such as breathing.
Eventually these functions will be impaired and you are likely to stop breathing and die.
Warning signs included confusion and headaches. Symptoms would normally occur very soon after drinking the water, but if the gut is absorbing the water more slowly then it can take longer. Treatment available for this type of sympthoms includes diuretics and drugs to reduce the swelling.
It is also a myth that “drinking more water helps clear out toxins”:
Kidneys filter toxins from our bloodstreams. Then the toxins clear through the urine. But drinking extra water each day does not improve the function of the kidneys. In fact, drinking large amounts of water surprisingly tends to reduce the kidney’s ability to function as a filter. It’s a slow but definite decline.
Drinking several litres over a relatively short period of time could be enough to cause water intoxication. Those most at risk include people taking ecstasy (this drug increases thirst and promotes the release of anti-diuretic hormones so more water is taken in but cannot be excreted) and elderly people (kidney function may be impaired).
We lose water all the time and so need to replace it and in normal circumstances should aim to drink about one and a half litres every day. During hot weather or exercise more should be consumed as dehydration can lead to bad breath, tiredness and a higher risk of bladder infections. However 1 litre and a half may be too much if you are going to the toilet more than once every two hours or so, especially if your urine is clear.
Our advice: Just drink when you’re thirsty and if you get thirsty very often also have a green, white or herbal tea rather than simple water.
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