Sunday, 1 May 2005

When quoting statistics about drinking water, think of the source

Over at A Capital Idea, Nicole has a post on how unchallenged statistics often wend their way into daily use, based on this Carl Bialik column. Numbers that originate from unquestioned assertions often find their way into regular use - such as the alarmist quote that "Canadian police estimate that more than 100,000 Web sites contain images of child sexual abuse." As Bialik notes:
It turns out the Canadian police were citing the statistic from a three-year-old article in a magazine that stopped publishing in 2003. The magazine's source is a U.S. agency that no longer exists. And the agency that has replaced it can't track down the original source of the stat. The lesson: An old stat can get new life when "experts" repeat it, especially when there is no conflicting version of the number.
Scary that the stat was then used "in public education and in funding proposals". Alarmist numbers probably lead to bad funding.

Which made me think, among the numbers that seem to have found their way into daily wisdom is the idea that you have to drink 8 glasses of water a day and that people are chronically dehydrated. As Snopes points out, this idea seems to have arisen from a random physician who claimed that people "need to learn they're not sick, only thirsty," and that drinking more water would cure diseases including "arthritis, angina, migraines, hypertension and asthma."

Here's the LA Times on the subject:
Kidney specialists do agree on one thing, however: that the 8-by-8 rule is a gross overestimate of any required minimum. To replace daily losses of water, an average-sized adult with healthy kidneys sitting in a temperate climate needs no more than one liter of fluid, according to Jurgen Schnermann, a kidney physiologist at the National Institutes of Health.

One liter is the equivalent of about four 8-ounce glasses. According to most estimates, that's roughly the amount of water most Americans get in solid food. In short, though doctors don't recommend it, many of us could cover our bare-minimum daily water needs without drinking anything during the day. (Link)

I've tried drinking 8 glasses of water a day. As the LA Times article notes, the result of that is merely a constant desire to use the loo.



What about those statistics that tell you the average human smallows XX spiders in his life?


Yes! Now there's one less thing to feel guilty about... I could never hit the 64 oz. mark and was sure I could feel my kidney shriveling inside me.
Now I just need to get someone to get the "every person should eat 8 8 oz. Reese's Fast Break bars every day" statistic into circulation. Those things are awesome.


But I really am always thirsty.


You do realise always being thirsty is dangerous, no? I once told a doctor that, and was promptly made to undergo all these tests for diabetes.


Not in that way. I just prefer to have a wet throat, especially in weather like this.

I probably drink at least two litres a day. Most of it comes out, of course, but I still prefer the feeling of hydration.


I guess what you consider the feeling of hydration, I consider the feeling of anxiety :)


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