There is no dispute that water constitutes the most important substance, after oxygen, when it comes to sustaining life any where in the Universe. The very fact that almost 71% of the earth's surface is covered with water symbolizes the omnipotence of this simple chemical molecule. Similarly water makes up a substantial component of all living creatures. It is rather interesting that scientists are not unanimous in their view regarding how much water is required daily to maintain good health. While some say higher the amount of water taken better it will be for the human health. But this is not shared by many who consider too much water consumption is dangerous. Many believe that water therapy is an established science advocating high consumption of water every day which can be much above the quantity recommended by nutritionists and physicians.
The controversy was given a new lease of life after the recent assertion by a Glasgow-based scientist that water therapy is a myth devoid of any scientific basis. Years of faith in water therapy is driven by the belief that it can prevent many health problems. Number of people, developing the habit to drink six to eight glasses of water every day, seems to be increasing thanks to the above conviction. There are others who are scared of dehydration of the body if "adequate' water is not consumed and force themselves to drink water frequently whether thirsty or not. Of course it is known that drinking "too much" water can lead to the medical condition known as "hyponatraemia" or imbalance in Sodium in the blood which can seriously hamper brain function, some time proving to be fatal.
The million dollar question a humble citizen is forced to ask is how much is "adequate" and what constitutes excess". As a thumb rule it has been suggested that one liter of water for every 1000 kC food consumed can meet body's water requirement which goes for replacement of water lost due to perspiration and other excretions. This adds up to 2 liters of water a day. What if some human beings cannot drink the recommended quantum of water? Where does the "thirst phenomenon" fits into this equation? Human body is endowed with a system of balancing water in the body through an automatic mechanism controlled by the brain and when there is a deficiency in water, the thirst factor is supposed to kick in. Under extreme duress conditions, the body tends to lose water uncontrollably, like in diarrhea, when medical intervention is necessary and nutralite solutions or iso-tonic preparations are administered for water restoration.
Thirst signal is controlled by the brain and depending on whether it is extra cellular thirst due to reduction in water volume or intra cellular thirst caused by excess osmolite levels with in the cells and communicated through the central nervous system in normally healthy humans. With age neurological response tends to become dull and as a sufficient precaution old people are advised to consume water regularly. On the other hand the trouble of going to the toilet frequently is a factor that restrains old people from taking water regularly. According to WHO water consumption for men has to be 3.7 liters per day while for women it should be 2.7 liters per day. Of course many foods consumed as a part of the diet contributes significantly to body's water need and wide variation is possible depending on the level of activity, type of food consumed, temperature and humidity levels and other factors. Insinuation against drinking water bottling industry that it is responsible for the much hyped up water therapy may be too far fetched though the growth of this industry might be largely due to this factor.
How does a layman decide about his water requirement?. Probably, in stead of listening to divergent views, it is advisable to consume as much as he feels like taking and go by doctor's advice when ever there are symptoms of dehydration.V.H.POTTY