Some ten years ago, drinking water outside of normal meals was unheard of. Today, however, it is habitual for people to walk around with water bottles and drink copious amounts of water daily.
For years, young children have been taught in school that one should drink several litres of water every day, so obviously this current hydration habit is actually good for you, or is it?
In 2007, Scientific American reported that a 28-year-old California woman died after competing in a radio station's water-drinking contest.
After downing some six liters of water in three hours in the "Hold Your Wee for a Wii" contest, Jennifer Strange vomited, went home with a splitting headache, and later died from water intoxication which is a form of hyponatremia. And she's not the only one.
In 2005 a fraternity ragging at California State University, left a 21-year-old man dead after he was forced to drink excessive amounts of water between rounds of push-ups in a cold basement.
In fact there are several recorded cases of death from drinking too much water.
Hyponatremia, according to Medicine Net, is a condition whereby salt (Potassium and Sodium) levels in our body drops to dangerously low levels due to dilution of the blood.
Generally, the blood Sodium level is between 135 and 145 millimoles per litre of blood. If this falls below 135 millimoles of sodium per litre of blood, then water intoxication occurs and if it falls below 125 millimoles then death.
Water intoxication? Really? Difficult as it may be to grasp that water can intoxicate you, that's the truth. In fact the Greek philosopher, Paracelsius, proclaimed several centuries ago that 'every substance we know is potentially a poison, if taken in the right amount'.
'The right amount' is the key here.
One of the basic principles of toxicology (study of poisons) is that 'the dose determines the poison'.
If taken in large amounts, even the most placid substance, such as water, may become a poison. The viability of a poison is generally determined by its toxicity - potential to kill.
Some substances such as Arsenic have a high toxicity, meaning that ingesting even a small amount may kill you.
Yet, you might be surprised to know that there is arsenic in your body right now. If you are a habitual smoker, then you have more arsenic in your body then the rest of us. So, why aren't you dead already, you ask?
Well that's because the Arsenic in your body is at such low levels that it is not yet toxic enough to kill. The dose determines the poison, remember. So, how exactly does too much water kill?
The How Stuff Works website explains that in humans the kidneys control the amount of water, salts and other solutes leaving the body.
When a person drinks too much water in a short period of time, the kidneys cannot flush it out fast enough and the blood becomes diluted. In our bodies, a delicate balance is maintained between essential elements, such as salts like Sodium, also known as electrolytes (yes the stuff in Powerade). Electrolytes inside a cell cannot pass through the cell wall so when the electrolyte level in blood drops too low compared to electrolyte level in cells, water must pass into the cell and dilute the cellular electrolytes to maintain the balance.
During hyponatremia conditions, the blood is severely diluted, so a large amount of water from the blood must enter the cells to re-instate electrolyte balance. As a result the cells get swollen (like a balloon) with the excess water.
The problem is that some cells aren't able to accommodate the expansion.
Brain cells are particularly vulnerable because they are tightly packaged inside a rigid boney cage (the skull) and they have almost zero room to expand and swell.
Brain edema, or swelling, can be disastrous. It can lead to irreversible brain damage causing severe headaches, seizures, coma, respiratory arrest, brain stem herniation and ultimately death.
If I've just put you off your healthy hydration habit, then let me reassure you.
Drinking water is a healthy habit indeed. One just has to be careful not to consume an abnormal amount of water in a short period of time.
In fact simply drinking too much water may not kill you, there are other factors in play.
Dr Heinz Valtin, a kidney specialist from Dartmouth Medical School says that every hour, a healthy kidney at rest can excrete upto one Litre of water and therefore a person can drink water at a rate of a Litre per hour without experiencing a net gain in water.
If that same person is running a marathon, however, the stress of the situation will increase vasopressin (a hormone that instructs the kidneys to conserve water) levels, reducing the kidney's excretion capacity to as low as 100 milliliters per hour. Drinking a Litre of water per hour under these conditions can potentially lead to a net gain in water thereby causing hyponatremia.
As a rule of thumb, you should balance what you're drinking with what you're excreting (sweat or urine).
But how does one know what he/she is excreting per hour? Yes, that's a difficult one. In that case I'd take Dr. Valtin's advice, 'just drink to your thirst'. Happy drinking!
* Mitesh Mudaliar is a Health Protection Officer and a Drinking Water Assessor in Christchurch, New Zealand. The views expressed here are his and not of this newspaper. For feedback, email mudaliar_m_m@hotmail.com.