ICE-COLD WATER AND YOU
There are lots of myths about drinking ice-cold water (hydration)
and regulating the temperature of the body. No question, a
glass of ice-cold water on a hot day gives you tremendous
satisfaction by cooling your mouth and stomach. But does it
really satisfy your thirst? Does it deliver water immediately
to all your tissues and cells? Does it cool down your body,
and reduce its temperature?
I have no idea where these opinions come from, either from
somebody's personal experience of cooling perception or just
from anecdotal info passed from one friend to another. Theoretically,
according to "The Biology of Human Survival" (Claude
A.Piantadosi, Oxford University Press, 2003, p.86) "a
70-kilogram person can drop body temperature approximately
1C by drinking a liter of water at 0C ", but in reality
it is difficult to imagine somebody using this amount of cold
water at once during racing activity. Using it in small portions
will practically reduce the cooling effect, because heat-cold
exchange will be imperceptible on the whole body scale.
I found no data supporting the idea that drinking cold water
reduces the body's temperature. If it were so, we would have
had it somewhere recorded in human history experience. The
law of survival would inevitably recruit this procedure in
human life in extreme hot weather conditions. The fact is
that we do the opposite to cold water drinking. Survival in
severe hot environment includes specific behavior, aimed at
reduction of heat by using shelters; wearing thick clothes
and making the body sweat by drinking hot tea.
As we know, our body looses liquid through sweating by drops
or by small portions over time, so replenishing it should
happen almost in the same manner. Thus taking a big portion
of water at once would not do the trick, as it may stay in
the stomach for a while before it can be absorbed on a cellular
level. Additionally, I'd like to bring up here another interesting
fact about drinking. The author of the book, mentioned above,
wrote, "it is important to note that the main stimulus
of drinking is thirst, which is regulated by plasma osmolarity,
not by temperature".
Therefore temperature influences our thirst only indirectly
through making our body sweat and loose body liquid. Evaporation
of this sweat, in its own turn, produces cooling effect. So
it has nothing to do with drinking ice-cold water. Morever,
when we drink cold water, it can't be absorbed immediately,
because it takes time for it to be heated up to achieve the
body temperature to be absorbed on a cellular level.
Now we have some logical facts showing us the true and mythical
sides of ice-cold water drinking, which have no real cooling
effect and should not be used as a body temperature reducing
mechanism. It doesn't quench our thirst or reduce our dehydration
more effectively than for instance normal temperature water.
What it really does for us is giving a pleasant feeling of
cold in the mouth and stomach - which are just a perception.
Dr.Romanov
Pose
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