Tiktaalik
Half True Scotsperson
- Joined
- Sep 29, 2006
- Messages
- 3,666
I'm not sure if this is of interest to anyone (or the correct forum), but it's one of my pet peeves. I got the following information from this article:
Water Drinking 8 X 8
(If that doesn't work try www.ajpregu.org & search for Valtin 2002).
Having lived in the desert (Mojave) for a number of years, I was often accused of being unhealthy because I generally didn't/don't drink 8, eight-ounce glasses of water (8 X 8) per day. I came across this literature review a few years ago, disputing the "you must drink 8 glasses of water per day to remain healthy" urban legend.
Basically, no scientific studies were found in support of 8 X 8. During a comprehensive search of the literature (100 references & search strategy in the back of the article) Valtin says he could not find an article where 8 X 8 was recommended on the basis of solid scientific evidence.
In addition, he asserts that recent experiments cast serious doubts on the often-asserted diuretic role of caffeinated drinks (except in non-caffeine drinkers, maybe). In other words, caffeinated and non-caffeinated caloric and non-caloric drinks performed equally well in keeping people sufficiently hydrated. So drinking soda does count as part of your daily fluid intake (yeah!).
Valtin refers to an argument of the "lay press" which he states as "our bodies consist mostly of water and our brains, blood, muscles, and bone are made up mainly of water. Therefore, we need water to function and survive and we need at least 8 eight-ounce glasses of water each day." He then says that "the second conclusion, in addition to being unproven, is a non-sequitor; it is aking to arguing that our homes run on electricity and that, therefore, every house needs at least 1000 ampere service."
He did note that cancer of the urinary bladder in men was reduced by high fluid intake, but that this holdds true even for men who drink only 6 glasses of water and that it of course can't be extrapolated to women (and that there's disagreement on this).
He notes that there is some evidence that water during/before meals produces satiety, and therefore it might be useful in weight loss.
Next: "The notion that a high fluid intake will facilitate bowel movements was tested by Chung, et al..." Nope. They only pee more.
Then the hazards:
In some cases, severe water intoxication could result, particularly in cases of poor renal function, diabetes, or use of Ecstasy. Mild hyponutremia (dilution of the plasma) is said to be common. This reflects an excess of water in the body rather than a decrease in sodium in many cases.
Other myths:
"If you're thirsty, you're already dehydrated." I've heard this one. Not true. "Thirst... is so sensitive, quick and accurate that it is hard to imagine that evolutionary development left us with a chronic water deficit that has to be compensated by forcing fluid intake."
"Dark urine means dehydration." Generally, "depth of color in urine will vary inversely with urinary volume." and "at nromal urinary volume, the plasma osmolality will be well within the normal range." So "the warning that dark urine reflects dehydration is alarmist and false in most instances."
In conclusion, he states that "I have found no scientific reports concluding that we all must "drink at least eight glasses of water a day." On the contrary, there are publications that state the opposite..."
"...I would argue even further that for the time being the burden of proof that everyone needs 8 X 8 should fall on those who persist in advocating the high fluid intake without, apparently, citing any scientific support."
My own conclusions: Don't worry about it. Not to say that one shouldn't drink plenty of fluids when working out, in a hot, dry environment, or when engaged in heavy labor. But if I don't feel thirsty, I'm not. I don't have to force-feed myself 8 glasses of water every day in some misguided attempt to be more "healthy". And don't get in the way of my caffeine fix!
There's tons more info in the article itself including where the urban legend may have come from and some other myths and benefits of drinking water...
Water Drinking 8 X 8
(If that doesn't work try www.ajpregu.org & search for Valtin 2002).
Having lived in the desert (Mojave) for a number of years, I was often accused of being unhealthy because I generally didn't/don't drink 8, eight-ounce glasses of water (8 X 8) per day. I came across this literature review a few years ago, disputing the "you must drink 8 glasses of water per day to remain healthy" urban legend.
Basically, no scientific studies were found in support of 8 X 8. During a comprehensive search of the literature (100 references & search strategy in the back of the article) Valtin says he could not find an article where 8 X 8 was recommended on the basis of solid scientific evidence.
In addition, he asserts that recent experiments cast serious doubts on the often-asserted diuretic role of caffeinated drinks (except in non-caffeine drinkers, maybe). In other words, caffeinated and non-caffeinated caloric and non-caloric drinks performed equally well in keeping people sufficiently hydrated. So drinking soda does count as part of your daily fluid intake (yeah!).
Valtin refers to an argument of the "lay press" which he states as "our bodies consist mostly of water and our brains, blood, muscles, and bone are made up mainly of water. Therefore, we need water to function and survive and we need at least 8 eight-ounce glasses of water each day." He then says that "the second conclusion, in addition to being unproven, is a non-sequitor; it is aking to arguing that our homes run on electricity and that, therefore, every house needs at least 1000 ampere service."
He did note that cancer of the urinary bladder in men was reduced by high fluid intake, but that this holdds true even for men who drink only 6 glasses of water and that it of course can't be extrapolated to women (and that there's disagreement on this).
He notes that there is some evidence that water during/before meals produces satiety, and therefore it might be useful in weight loss.
Next: "The notion that a high fluid intake will facilitate bowel movements was tested by Chung, et al..." Nope. They only pee more.
Then the hazards:
In some cases, severe water intoxication could result, particularly in cases of poor renal function, diabetes, or use of Ecstasy. Mild hyponutremia (dilution of the plasma) is said to be common. This reflects an excess of water in the body rather than a decrease in sodium in many cases.
Other myths:
"If you're thirsty, you're already dehydrated." I've heard this one. Not true. "Thirst... is so sensitive, quick and accurate that it is hard to imagine that evolutionary development left us with a chronic water deficit that has to be compensated by forcing fluid intake."
"Dark urine means dehydration." Generally, "depth of color in urine will vary inversely with urinary volume." and "at nromal urinary volume, the plasma osmolality will be well within the normal range." So "the warning that dark urine reflects dehydration is alarmist and false in most instances."
In conclusion, he states that "I have found no scientific reports concluding that we all must "drink at least eight glasses of water a day." On the contrary, there are publications that state the opposite..."
"...I would argue even further that for the time being the burden of proof that everyone needs 8 X 8 should fall on those who persist in advocating the high fluid intake without, apparently, citing any scientific support."
My own conclusions: Don't worry about it. Not to say that one shouldn't drink plenty of fluids when working out, in a hot, dry environment, or when engaged in heavy labor. But if I don't feel thirsty, I'm not. I don't have to force-feed myself 8 glasses of water every day in some misguided attempt to be more "healthy". And don't get in the way of my caffeine fix!
There's tons more info in the article itself including where the urban legend may have come from and some other myths and benefits of drinking water...
I prefer just to drink my three cups of tea and a glass of water of the course of a day.