Saturday, November 27, 2010

Lemming Tracks: "8 x 8" Water Rule, Real Research; Beer and Pretzels

Ever tried drinking those eight glasses of water - eight-ounce glasses, of course?

Somewhere around the time when experts warned that everything caused cancer1, The Lemming decided to drink as much as was needed to feel comfortable, and leave it at that.

Sloshing Toward Enlightenment

Ever wonder, as you sloshed between the lavatory and the water faucet, why the eight x eight rule was so 'scientific?'

Turns out, although 'everybody knows' that the eight x eight rule is very 'scientific,' the idea is about as solid as the emperor's new clothes.

About eight years ago (yet another eight!), a brave soul at the Dartmouth Medical School, Lebanon, New Hampshire's Department of Physiology decided to find out where the eight x eight rule came from.

Even though The New York Times itself had published the rule.


Here's what he found.

Or, rather, didn't find.

Take a Deep Breath: Journalese Ahead

The Lemming will be back, after this rather extensive - and possibly boring - excerpt from a refreshingly competent bit of research.

Real research: with citations and everything. Not the sort of 'expert' proclamations you see in news media.

" 'Drink at least eight glasses of water a day.' Really? Is there scientific evidence for '8 × 8'?"
Heinz Valtin, with the Technical Assistance of Sheila A. Gorman
Department of Physiology, Dartmouth Medical School, Lebanon, New Hampshire 03756
Am J Physiol Regul Integr Comp Physiol 283: R993-R1004, 2002.
First published August 8, 2002; doi:10.1152/ajpregu.00365.2002 0363-6119/02 $5.00 (November 2002)


"Despite the seemingly ubiquitous admonition to "drink at least eight 8-oz glasses of water a day" (with an accompanying reminder that beverages containing caffeine and alcohol do not count), rigorous proof for this counsel appears to be lacking. This review sought to find the origin of this advice (called "8 × 8" for short) and to examine the scientific evidence, if any, that might support it. The search included not only electronic modes but also a cursory examination of the older literature that is not covered in electronic databases and, most importantly and fruitfully, extensive consultation with several nutritionists who specialize in the field of thirst and drinking fluids. No scientific studies were found in support of 8 × 8. Rather, surveys of food and fluid intake on thousands of adults of both genders, ... strongly suggest that such large amounts are not needed because the surveyed persons were presumably healthy and certainly not overtly ill. This conclusion is supported by published studies showing that caffeinated drinks (and, to a lesser extent, mild alcoholic beverages like beer in moderation) may indeed be counted toward the daily total, as well as by the large body of published experiments that attest to the precision and effectiveness of the osmoregulatory system for maintaining water balance...."


"WE SEE THE EXHORTATION EVERYWHERE: 'drink at least eight glasses of water a day' (17). The advice comes not only (as in the above quote) from a respected health columnist of The New York Times, but also from numerous writers in the popular press (3, 6, 10, 26, 54). Some, perhaps many, physicians counsel their patients in a similar vein, both orally and in writing. So prevalent is the recommendation that it is now commonly expressed simply as '8 × 8' (signifying that each of the 8 glasses in question must have a volume of 8 oz).

"As we look around us in our daily activities, we can observe how slavishly the exhortation is being followed. Everywhere, people are carrying bottles of water and taking frequent sips from them. Prior to September 11, when there was little restriction on how much baggage passengers could carry onboard airplanes..."


"Despite a comprehensive search of the literature (see SEARCH STRATEGY, end of article), I have not been able to find an article where 8 × 8 is recommended on the basis of solid scientific evidence. The closest reference was an obituary on the renowned nutritionist Fredrick J. Stare, brought to my attention by Dr. Barbara Rolls, an expert on the topic of thirst (76). The obituary (77) stated, in part, that Dr. Stare "was an early champion of drinking at least six glasses of water a day." A former colleague of Dr. Stare, Dr. Elizabeth Whelan (82), found the following passage in a book that Dr. Stare coauthored with Dr. Margaret McWilliams in 1974 (81):
"How much water each day? This is usually well regulated by various physiological mechanisms, but for the average adult, somewhere around 6 to 8 glasses per 24 hours and this can be in the form of coffee, tea, milk, soft drinks, beer, etc. Fruits and vegetables are also good sources of water.
"The passage, which is not referenced, appears as part of a very brief section at the very end of the book, after the authors have discussed various aspects of nutrition (calories, carbohydrates, fats, proteins, vitamins, etc.) in the preceding 174 pages. Thus water is taken up in this book almost as an afterthought....

But, Dr. Stare had a "leading position in the field of nutrition." He was an "exert," in other words.

Back to the article.

"Furthermore, lest the advocates of 8 × 8 now adopt this quote from Dr. Stare as scientific evidence, let me point out the following: 1) this is an apparently casual opinion by Drs. Stare and McWilliams, which is undocumented by any scientific experiment; 2) there is a huge difference between 'somewhere around 6 to 8 glasses' and 'at least eight glasses' (17), and it is the latter recommendation that is in question; 3) in Drs. Stare and McWilliams's passage, caffeinated and alcoholic drinks such as coffee, tea, soft drinks, and beer are allowed, whereas these categories are excluded by the proponents of 8 × 8; and 4) Drs. Stare and McWilliams introduce their estimate with the statement that water intake is 'usually well regulated by various physiological mechanisms,' whereas the advocates of 8 × 8 claim that if we wait for these mechanisms to determine our water intake we will already be dehydrated.

"According to J. Papai (65), P. Thomas has suggested a different origin for 8 × 8. Thomas reminds us that in 1945 the Food and Nutrition Board of the National Research Council wrote (31):
"A suitable allowance of water for adults is 2.5 liters daily in most instances. An ordinary standard for diverse persons is 1 milliliter for each calorie of food. Most of this quantity is contained in prepared foods.
"Thomas suggests that the last sentence was not heeded, and the recommendation was therefore erroneously interpreted as eight glasses of water to be drunk each day. The Food and Nutrition Board is currently reevaluating its recommendation [see below, under National Academy of Sciences (USA), Food and Nutrition Board]...."

I am Not an Expert: But I have Seen Human Beings

Ever get the impression that some 'experts,' particularly the 'child-rearing experts' of post-WWII America, had heard of human beings, but never actually seen one?

The Lemming has seen human beings. Living ones. In fact, I have been accepted into a small community of these strange creatures: here in the heart of darkest Minnesota.

After decades of observations, I have come to a few conclusions, about how healthy human beings eat foods and drink fluids.

When a human being is thirsty, it probably needs water or other fluids.

When a human being is not thirsty, it probably doesn't need water or other fluids just then.

In fact - and this may be the most startling discovery of all - human beings have been known to be thirsty, waited several minutes before ingesting fluids: AND SURVIVED!!

Perhaps a panel of 'experts' could get a government grant - a few million dollars should do - to study human beings in the wild.

The Lemming suggests that grant writers focus on a topic of manageable scope: like "A Longitudinal Study of Fluid Intake Among Indigenous Populations in Central Minnesota, With Particular Emphasis on the Ratio of Beer to Pretzels."

More silliness:
1 To be fair, those often-anonymous experts didn't quite name everything on Earth as a carcinogen. On the other hand, one of my college textbooks had a list of "known carcinogens." Full page. Fine print.

We've got a phrase for that sort of thing now: "junk science." (Junk May 18, 2009)

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