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Hyponatremia – Is there such a thing as too much water?

Hyponatremia – Is there such a thing as too much water?

Anyone who has picked up a health or fitness magazine in the last 10 years will know that drinking water has many health benefits.  The human body is about 70% water so keeping well hydrated aids weight loss and keeps you looking younger and full of life.  Experts recommend drinking 8-10 glasses of water throughout the day and the consequences of being dehydrated are well recognised.  But is there such a thing as too much when it comes to hydration?

In this case, too much of a good thing is most definitely a bad thing.  Sodium balance between the fluid outside and inside the body’s cells is vital to keeping the body’s systems functioning.  When we drink too much water or fluid that has a low concentration of salts, the fluid outside the cells becomes very dilute and disrupts the balance.  Water will move into the cells to equalise the sodium concentrations and the cells begin to swell.  This isn’t a concern in most of the body’s tissues but in the skull there is very limited space to accommodate swelling of brain cells.  The condition of low sodium concentration in body fluids outside of cells is known as Hyponatremia, and brain swelling is responsible for the majority of symptoms associated with this condition.  Most common symptoms are fatigue, confusion, headache, muscle cramps and weakness, nausea and vomiting, and, if left untreated, can lead to eventual coma and death.

Don’t throw away your water bottle quite yet! Although serious, the condition is relatively rare and can be avoided.  Certain medical conditions such as congestive heart failure, cirrhosis, and the syndrome of inappropriate anti-diuretic hormone secretion (SIADH) are associated with a higher risk of Hyponatremia.  A growing concern is the incidence in recreational endurance athletes.  With a constant supply of water along most endurance race routes, slower athletes have time to ingest large amounts of water – often because they fear becoming dehydrated – and are not exercising at an intensity that allows this excess fluid to be lost by sweating.  Contrary to popular advice, thirst doesn’t indicate that you are already too dehydrated and the best way to avoid this condition during exercise is simply to drink according to thirst.  Drinking sports drinks containing electrolytes will also ensure the sodium levels in your body remain balanced.

How much water should you drink each day? A simple question but with no easy answer. There are many guidelines but in truth your water needs depend on many factors which include but are not limited to your health, fitness levels and even where you live. Water intoxication is a very uncommon condition but unless you are running a long distance race or an infant, it is not something that one should spend too much time worrying about.



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