On Tue, 27 Mar 2001, Jeff Ricker wrote:
> We have had discussions before on TIPS about the origins of what seems
> to be a myth regarding the need to drink eight glasses of water per day.
> For those who may discuss various myths in their courses, you may want
> to take a look at page 61 of the New Yorker. A cartoon on this page
> shows a man sitting at a bar and saying to the bartender: "Water,
> Al--six to eight glasses." For you Powerpointers among us (yes, I mean
> you, Stephen), it could provide a nice introduction to a discussion of
> myths in general.
Thanks, Jeff. In return, I offer:
http://www.comics.com/comics/forbetter/archive/forbetter-20010318.html
(from the great Canadian cartoonist, Lynn Johnson, March 18/01)
On progress on the 6-8 glasses front, I offer:
Pro:
Michaud et al (1999) report an inverse relationship between
fluid intake and the risk of bladder cancer in men. While
correlational, there are good reasons to believe
that the results may, in fact be causal.
However, as this is a recent discovery, it's unlikely to be the
motivation for people drinking 6-8 glasses. How many students
will tell you they're doing it to avoid bladder cancer?
Anti:
Jordan et al (1999) report that drinking 480 ml of tap water
acutely raises the blood pressure in controls and in patients
with severe low blood pressure due to autonomic failure. While
this can be therapeutic for the patients, it sometimes worked too
well and for these, "drinking water can result in dangerously
high blood pressure values in the supine position". Note that it
also raised blood pressure in controls. As 8 glasses of water is
2000 ml, people following the rule are drinking four times as
much as in this experiment.
(So drink water and die of a stroke caused by high blood
pressure; drink water and don't die of bladder cancer. Your
choice.)
More anti:
An article in the Montreal Gazette (Jan 3/01) reprinted from the
Los Angeles Times, by Benedict Carey. Sub-head: "People who see
it as a healthy cure-all are victims of fashion and fiction."
Some bits:
"Consider that first commandment of good health: drink at least
eight 8-ounce glasses or 2 liters of water a day...Most
nutritionists have no idea where it comes from. "I can't even
tell you that", says Barbara Rolls, a nutrition researcher at
Penn State U. "and I've written a book on water".
And "Kidney specialists do agree...that the..rule is a gross
overestimate of any required minimum....In short, although
doctors don't recommend it, many of us could cover our
bare-minimum daily water needs without drinking anything during
the day."
I'll drink to that.
-Stephen
References
Jordan, J. et al (1999). A potent pressor response elicited
by drinking water. The Lancet, 353, 723--
Michaud, D. et al (1999). Fluid intake and risk of bladder cancer
in men. New England Journal of Medicine, 340, 1390-7
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Stephen Black, Ph.D. tel: (819) 822-9600 ext 2470
Department of Psychology fax: (819) 822-9661
Bishop's University e-mail: [EMAIL PROTECTED]
Lennoxville, QC
J1M 1Z7
Canada Department web page at http://www.ubishops.ca/ccc/div/soc/psy
Check out TIPS listserv for teachers of psychology at:
http://www.frostburg.edu/dept/psyc/southerly/tips/
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