Dehydration
Thread Starter
Join Date: May 2002
Location: Who can say?
Posts: 1,700
Likes: 0
Received 0 Likes
on
0 Posts
Dehydration
This subject came up in another thread. How you deal with it is not the issue here. Recognising the signs and managing it is, hence the new thread.
I was emailed this today:-
Health Tip: The Importance of Water
We all know that water is important but I've never seen it written down like this before.
75% of Americans are chronically dehydrated.
In 37% of Americans, the thirst mechanism is so weak that it is often mistaken for hunger.
Even MILD dehydration will slow down one's metabolism as much as 3%.
One glass of water shuts down midnight hunger pangs for almost 100% of the dieters studied in a U-Washington study.
Lack of water is the #1 trigger of daytime fatigue.
Preliminary research indicates that 8-10 glasses of water a day could significantly ease back and joint pain for up to 80% of sufferers.
A mere 2% drop in body water can trigger fuzzy short-term memory, trouble with basic math, and difficulty focusing on the computer screen!
Drinking 5 glasses of water daily decreases the risk of colon cancer by 45%, plus it can slash the risk of breast cancer by 79% and one is 50% less likely to develop bladder cancer.
Are you drinking the amount of water you should every day?
I was emailed this today:-
Health Tip: The Importance of Water
We all know that water is important but I've never seen it written down like this before.
75% of Americans are chronically dehydrated.
In 37% of Americans, the thirst mechanism is so weak that it is often mistaken for hunger.
Even MILD dehydration will slow down one's metabolism as much as 3%.
One glass of water shuts down midnight hunger pangs for almost 100% of the dieters studied in a U-Washington study.
Lack of water is the #1 trigger of daytime fatigue.
Preliminary research indicates that 8-10 glasses of water a day could significantly ease back and joint pain for up to 80% of sufferers.
A mere 2% drop in body water can trigger fuzzy short-term memory, trouble with basic math, and difficulty focusing on the computer screen!
Drinking 5 glasses of water daily decreases the risk of colon cancer by 45%, plus it can slash the risk of breast cancer by 79% and one is 50% less likely to develop bladder cancer.
Are you drinking the amount of water you should every day?
Join Date: Jun 2002
Location: The Far Side
Posts: 94
Likes: 0
Received 0 Likes
on
0 Posts
Captain Stable,
Can you please confirm this study source? I would like to use some of these thoughts for our Human Factors awareness course, as it presents this problem of dehydration of crew so clearly. Thanks.
Can you please confirm this study source? I would like to use some of these thoughts for our Human Factors awareness course, as it presents this problem of dehydration of crew so clearly. Thanks.
Thread Starter
Join Date: May 2002
Location: Who can say?
Posts: 1,700
Likes: 0
Received 0 Likes
on
0 Posts
Sorry, I can't. As you see it is as it was emailed to me and since then the sender has gone off on vacation. CAA Medical Branch could possibly shed some light.
Drain Bamaged
I'm with Fugro airborne and dehydration is a safety issue for us, especially in hot weather environment or, during our long low level survey flights.
I was given this "memo" on my last medical :
WATER REQUIREMENT FOR HUMANS
8 glasses of water is the normal daily requirement for an average sedentary person. However, if you get involved in various activities, your requirement goes up. How much it goes up depends upon your weight, your gender, the surronding temperature and humidity, how fit you are and how intensely you're working.
Based on a 135 pound active person, the following will give an estimate of how much extra fluid is lost in some examples of other activities.
ACTIVITY---------------------------------------------EXTRA 8 OZ GLASSES
--------------------------------------------------------OF WATER NEEDED
5 hrs airline flight (only as a pax)------------------------------4 - 5
Sitting at an afternoon balgame, 3 hrs, 32C-----------------2½ - 5
Watching the ballgame at home on TV, 3 hrs----------------1 - 2
Swimming 1 hr, pool temperature, 20C-----------------------½ - 2
Walking 1 hr, indoor treadmill, 21C----------------------------1½ - 2½
Walking 1 hr, outdoors, 30C------------------------------------2 - 3½
Hiking 4 hrs, rolling hills, 20C-----------------------------------10 - 14
Hiking 4 hrs, rolling hills, 30C-----------------------------------13 - 16
Running 1 hr, 6 mph, 30C---------------------------------------5
Tennis 1 hr---------------------------------------------------------2 - 10
Sleeping 2½ extra hrs-------------------------------------------½
End of the memo.
The next safety issue related to water for us (as we are often in remote areas) is to be sure to drink "clean water" but that's another topic.
I was given this "memo" on my last medical :
WATER REQUIREMENT FOR HUMANS
8 glasses of water is the normal daily requirement for an average sedentary person. However, if you get involved in various activities, your requirement goes up. How much it goes up depends upon your weight, your gender, the surronding temperature and humidity, how fit you are and how intensely you're working.
Based on a 135 pound active person, the following will give an estimate of how much extra fluid is lost in some examples of other activities.
ACTIVITY---------------------------------------------EXTRA 8 OZ GLASSES
--------------------------------------------------------OF WATER NEEDED
5 hrs airline flight (only as a pax)------------------------------4 - 5
Sitting at an afternoon balgame, 3 hrs, 32C-----------------2½ - 5
Watching the ballgame at home on TV, 3 hrs----------------1 - 2
Swimming 1 hr, pool temperature, 20C-----------------------½ - 2
Walking 1 hr, indoor treadmill, 21C----------------------------1½ - 2½
Walking 1 hr, outdoors, 30C------------------------------------2 - 3½
Hiking 4 hrs, rolling hills, 20C-----------------------------------10 - 14
Hiking 4 hrs, rolling hills, 30C-----------------------------------13 - 16
Running 1 hr, 6 mph, 30C---------------------------------------5
Tennis 1 hr---------------------------------------------------------2 - 10
Sleeping 2½ extra hrs-------------------------------------------½
End of the memo.
The next safety issue related to water for us (as we are often in remote areas) is to be sure to drink "clean water" but that's another topic.
Join Date: Jun 2002
Location: Houston, Texas
Posts: 25
Likes: 0
Received 0 Likes
on
0 Posts
Here's a neat trick: consuming a glass of water can help to resolve the symptoms of hypoglycemia. (Short term) In other words, you've reached T.O.D. and you're starting to "bonk". No nourishment is available or you don't have the time due to pace of OPS, consume some water.
Cheers,
DAN
LJDRVR
P.S.- b55. If you need a reference source for physiology to develop a human factors curriculum, I highly recommend
"FIT TO FLY, A PILOT'S GUIDE TO HEALTH & SAFETY." By Richard O. Reinhart, M.D. (ISBN 0-8306-2059-1)
Cheers,
DAN
LJDRVR
P.S.- b55. If you need a reference source for physiology to develop a human factors curriculum, I highly recommend
"FIT TO FLY, A PILOT'S GUIDE TO HEALTH & SAFETY." By Richard O. Reinhart, M.D. (ISBN 0-8306-2059-1)
PPRuNeaholic
Join Date: Jun 2000
Location: Cairns FNQ
Posts: 3,255
Likes: 0
Received 0 Likes
on
0 Posts
I'm prepared to bet that nobody on planet earth drinks as much water as they should. And, yes, in this part of the world, the cleanliness of the water IS an issue... 
Join Date: Jun 2002
Location: Melbourne, Australia
Posts: 22
Likes: 0
Received 0 Likes
on
0 Posts
Claim: 75% of Americans are "chronically dehydrated" because they fail to drink eight glasses of water per day.
Status: False.
Example: [Collected on the Internet, 2001]
75% of Americans are chronically dehydrated.
In 37% of Americans, the thirst mechanism is so weak that it is often mistaken for hunger.
Even mild dehydration will slow down one's metabolism as much as 3%.
One glass of water shut down midnight hunger pangs for almost 100% of the dieters studied in a U-Washington study.
Lack of water is the number one trigger of daytime fatigue.
Preliminary research indicates that 8-10 glasses of water a day could significantly ease back and joint pain for up to 80% of sufferers.
A mere 2% drop in body water can trigger fuzzy short-term memory, trouble with basic math, and difficulty focusing on the computer screen or on a printed page.
Drinking 5 glasses of water daily decreases the risk of colon cancer by 45%, plus it can slash the risk of breast cancer by 79%, and one is 50% less likely to develop bladder cancer.
Are you drinking a healthy amount of water each day?
Origins: "You need to drink eight to ten glasses of water per day to be healthy" is one of our more widely-known basic health tips. But do we really need to drink that much water on a daily basis?
In general, to remain healthy we need to take in enough water to replace the amount we lose daily through excretion, perspiration, and other bodily functions, but that amount can vary widely from person to person, based upon a variety of factors such as age, physical condition, activity level, and climate. The "8-10 glasses of water per day" is a rule of thumb, not an absolute minimum, and not of all of our water intake need come in the form of drinking water.
The origins of the 8-10 glasses per day figure remain elusive. As a recent Los Angeles Times article on the subject reported:
Consider that first commandment of good health: Drink at least eight 8-ounce glasses of water a day. This unquestioned rule is itself a question mark. Most nutritionists have no idea where it comes from. "I can't even tell you that," says Barbara Rolls, a nutrition researcher at Pennsylvania State University, "and I've written a book on water."
Some say the number was derived from fluid intake measurements taken decades ago among hospital patients on IVs; others say it's less a measure of what people need than a convenient reference point, especially for those who are prone to dehydration, such as many elderly people.
The consensus seems to be that the average person loses ten cups (where one cup = eight ounces) of fluid per day but also takes in four cups of water from food, leaving a need to drink only six glasses to make up the difference, a bit short of the recommended eight to ten glasses per day. But according to the above-cited article, medical experts don't agree that even that much water is necessary:
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.
Certainly there are beneficial health effects attendant with being adequately hydrated, and some studies have seemingly demonstrated correlations between such variables as increased water intake and a decreased risk of colon cancer. But are 75% of Americans really "chronically dehydrated," as claimed in the anonymous e-mail quoted in our example? Many of the notions (and dubious "facts") presented in that e-mail seem to have been taken from the book Your Body's Many Cries for Water, by Fereydoon Batmanghelidj. Dr. Batmanghelidj, an Iranian-born physician who now lives in the USA, maintains that people "need to learn they're not sick, only thirsty,'' and that simply drinking more water "cures many diseases like arthritis, angina, migraines, hypertension and asthma." However, he arrived at his conclusions through reading, not research, and he claims that his ideas represent a "paradigm shift" that required him to self-publish his book lest his findings "be suppressed.''
Other doctors certainly take issue with his figures:
[S]ome nutritionists insist that half the country is walking around dehydrated. We drink too much coffee, tea and sodas containing caffeine, which prompts the body to lose water, they say; and when we are dehydrated, we don't know enough to drink.
Can it be so? Should healthy adults really be stalking the water cooler to protect themselves from creeping dehydration?
Not at all, doctors say. "The notion that there is widespread dehydration has no basis in medical fact," says Dr. Robert Alpern, dean of the medical school at the University of Texas Southwestern Medical Center in Dallas.
Doctors from a wide range of specialties agree: By all evidence, we are a well-hydrated nation. Furthermore, they say, the current infatuation with water as an all-purpose health potion -- tonic for the skin, key to weight loss -- is a blend of fashion and fiction and very little science.
Additionally, the idea that one must specifically drink water because the diuretic effects of caffeinated drinks such as coffee, tea, and soda actually produce a net loss of fluid appears to be erroneous. The average person retains about half to two-thirds the amount of fluid taken in by consuming these types of beverages, and those who regularly consume caffeinated drinks retain even more:
Regular coffee and tea drinkers become accustomed to caffeine and lose little, if any, fluid. In a study published in the October issue of the Journal of the American College of Nutrition, researchers at the Center for Human Nutrition in Omaha measured how different combinations of water, coffee and caffeinated sodas affected the hydration status of 18 healthy adults who drink caffeinated beverages routinely.
"We found no significant differences at all," says nutritionist Ann Grandjean, the study's lead author. "The purpose of the study was to find out if caffeine is dehydrating in healthy people who are drinking normal amounts of it. It is not."
The same goes for tea, juice, milk and caffeinated sodas: One glass provides about the same amount of hydrating fluid as a glass of water. The only common drinks that produce a net loss of fluids are those containing alcohol -- and usually it takes more than one of those to cause noticeable dehydration, doctors say.
The best general advice (keeping in mind that there are always exceptions) is to rely upon your normal senses. If you feel thirsty, drink -- if you don't feel thirsty, don't drink unless you want to. The exhortation that we all need to satisfy an arbitrarily rigid rule about how much water we must drink every day was aptly skewered in a letter by a Los Angeles Times reader:
Although not trained in medicine or nutrition, I intuitively knew that the advice to drink eight glasses of water per day was nonsense. The advice fully meets three important criteria for being an American health urban legend: excess, public virtue, and the search for a cheap "magic bullet."
Last updated: 6 February 2001
The URL for this page is http://www.snopes.com/toxins/water.htm
Click here to e-mail this page to a friend
Urban Legends Reference Pages © 1995-2001
by Barbara and David P. Mikkelson
This material may not be reproduced without permission
--------------------------------------------------------------------------------
Sources:
Batmanghelidj, Fereydoon. Your Body's Many Cries for Water.
Global Health Solutions, 1995. ISBN 0-962-99423-5.
Carey, Benedict. "Hard to Swallow."
Los Angeles Times. 20 November 2001 (Health; p. 1).
Foreman, Judy. "The Water Fad Has People Soaking It Up."
The Boston Globe. 11 May 1998 (p. C1).
Hoolihan, Charlie. "Body Needs Plenty of Water to Work."
The [New Orleans] Times-Picayune. 31 May 1998.
Los Angeles Times. "All That Water Advice Just Doesn't Wash."
15 January 2001 (Health; p. 7).
Los Angeles Times. "Readers Take Issue with Article About Water Consumption."
25 January 2000 (Health; p. 5).
The Toronto Star. "Distilling Water Facts from Water Fiction."
21 March 1999.
Status: False.
Example: [Collected on the Internet, 2001]
75% of Americans are chronically dehydrated.
In 37% of Americans, the thirst mechanism is so weak that it is often mistaken for hunger.
Even mild dehydration will slow down one's metabolism as much as 3%.
One glass of water shut down midnight hunger pangs for almost 100% of the dieters studied in a U-Washington study.
Lack of water is the number one trigger of daytime fatigue.
Preliminary research indicates that 8-10 glasses of water a day could significantly ease back and joint pain for up to 80% of sufferers.
A mere 2% drop in body water can trigger fuzzy short-term memory, trouble with basic math, and difficulty focusing on the computer screen or on a printed page.
Drinking 5 glasses of water daily decreases the risk of colon cancer by 45%, plus it can slash the risk of breast cancer by 79%, and one is 50% less likely to develop bladder cancer.
Are you drinking a healthy amount of water each day?
Origins: "You need to drink eight to ten glasses of water per day to be healthy" is one of our more widely-known basic health tips. But do we really need to drink that much water on a daily basis?
In general, to remain healthy we need to take in enough water to replace the amount we lose daily through excretion, perspiration, and other bodily functions, but that amount can vary widely from person to person, based upon a variety of factors such as age, physical condition, activity level, and climate. The "8-10 glasses of water per day" is a rule of thumb, not an absolute minimum, and not of all of our water intake need come in the form of drinking water.
The origins of the 8-10 glasses per day figure remain elusive. As a recent Los Angeles Times article on the subject reported:
Consider that first commandment of good health: Drink at least eight 8-ounce glasses of water a day. This unquestioned rule is itself a question mark. Most nutritionists have no idea where it comes from. "I can't even tell you that," says Barbara Rolls, a nutrition researcher at Pennsylvania State University, "and I've written a book on water."
Some say the number was derived from fluid intake measurements taken decades ago among hospital patients on IVs; others say it's less a measure of what people need than a convenient reference point, especially for those who are prone to dehydration, such as many elderly people.
The consensus seems to be that the average person loses ten cups (where one cup = eight ounces) of fluid per day but also takes in four cups of water from food, leaving a need to drink only six glasses to make up the difference, a bit short of the recommended eight to ten glasses per day. But according to the above-cited article, medical experts don't agree that even that much water is necessary:
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.
Certainly there are beneficial health effects attendant with being adequately hydrated, and some studies have seemingly demonstrated correlations between such variables as increased water intake and a decreased risk of colon cancer. But are 75% of Americans really "chronically dehydrated," as claimed in the anonymous e-mail quoted in our example? Many of the notions (and dubious "facts") presented in that e-mail seem to have been taken from the book Your Body's Many Cries for Water, by Fereydoon Batmanghelidj. Dr. Batmanghelidj, an Iranian-born physician who now lives in the USA, maintains that people "need to learn they're not sick, only thirsty,'' and that simply drinking more water "cures many diseases like arthritis, angina, migraines, hypertension and asthma." However, he arrived at his conclusions through reading, not research, and he claims that his ideas represent a "paradigm shift" that required him to self-publish his book lest his findings "be suppressed.''
Other doctors certainly take issue with his figures:
[S]ome nutritionists insist that half the country is walking around dehydrated. We drink too much coffee, tea and sodas containing caffeine, which prompts the body to lose water, they say; and when we are dehydrated, we don't know enough to drink.
Can it be so? Should healthy adults really be stalking the water cooler to protect themselves from creeping dehydration?
Not at all, doctors say. "The notion that there is widespread dehydration has no basis in medical fact," says Dr. Robert Alpern, dean of the medical school at the University of Texas Southwestern Medical Center in Dallas.
Doctors from a wide range of specialties agree: By all evidence, we are a well-hydrated nation. Furthermore, they say, the current infatuation with water as an all-purpose health potion -- tonic for the skin, key to weight loss -- is a blend of fashion and fiction and very little science.
Additionally, the idea that one must specifically drink water because the diuretic effects of caffeinated drinks such as coffee, tea, and soda actually produce a net loss of fluid appears to be erroneous. The average person retains about half to two-thirds the amount of fluid taken in by consuming these types of beverages, and those who regularly consume caffeinated drinks retain even more:
Regular coffee and tea drinkers become accustomed to caffeine and lose little, if any, fluid. In a study published in the October issue of the Journal of the American College of Nutrition, researchers at the Center for Human Nutrition in Omaha measured how different combinations of water, coffee and caffeinated sodas affected the hydration status of 18 healthy adults who drink caffeinated beverages routinely.
"We found no significant differences at all," says nutritionist Ann Grandjean, the study's lead author. "The purpose of the study was to find out if caffeine is dehydrating in healthy people who are drinking normal amounts of it. It is not."
The same goes for tea, juice, milk and caffeinated sodas: One glass provides about the same amount of hydrating fluid as a glass of water. The only common drinks that produce a net loss of fluids are those containing alcohol -- and usually it takes more than one of those to cause noticeable dehydration, doctors say.
The best general advice (keeping in mind that there are always exceptions) is to rely upon your normal senses. If you feel thirsty, drink -- if you don't feel thirsty, don't drink unless you want to. The exhortation that we all need to satisfy an arbitrarily rigid rule about how much water we must drink every day was aptly skewered in a letter by a Los Angeles Times reader:
Although not trained in medicine or nutrition, I intuitively knew that the advice to drink eight glasses of water per day was nonsense. The advice fully meets three important criteria for being an American health urban legend: excess, public virtue, and the search for a cheap "magic bullet."
Last updated: 6 February 2001
The URL for this page is http://www.snopes.com/toxins/water.htm
Click here to e-mail this page to a friend
Urban Legends Reference Pages © 1995-2001
by Barbara and David P. Mikkelson
This material may not be reproduced without permission
--------------------------------------------------------------------------------
Sources:
Batmanghelidj, Fereydoon. Your Body's Many Cries for Water.
Global Health Solutions, 1995. ISBN 0-962-99423-5.
Carey, Benedict. "Hard to Swallow."
Los Angeles Times. 20 November 2001 (Health; p. 1).
Foreman, Judy. "The Water Fad Has People Soaking It Up."
The Boston Globe. 11 May 1998 (p. C1).
Hoolihan, Charlie. "Body Needs Plenty of Water to Work."
The [New Orleans] Times-Picayune. 31 May 1998.
Los Angeles Times. "All That Water Advice Just Doesn't Wash."
15 January 2001 (Health; p. 7).
Los Angeles Times. "Readers Take Issue with Article About Water Consumption."
25 January 2000 (Health; p. 5).
The Toronto Star. "Distilling Water Facts from Water Fiction."
21 March 1999.
Join Date: Jul 2002
Location: Canada
Posts: 31
Likes: 0
Received 0 Likes
on
0 Posts
Dehydration
Without a doubt, very interesting stuff. Especially since I have always been under the impression that 8 glasses of water a day was considered a healthy minimum!
The sources that were posted with regards to water requirements seem to be based on your average individual. I think it may be useful to point out that a soaking wet towel would be dry in close to 30 minutes in a pressurized cabin due to the lack of humidity. Would it not be fair to say that this type of environment can help lead to dehydration?
I am no Doctor. However, as a part-time Personal Trainer, water consumption has always been a very large part of my program, for performance and health. Since people on the average tend to have difficuly in consuming even small amounts of water, wouldn't it be best to stay on the safe side and continue to encourage water consumption in our fellow pilots (and passengers, for that matter!)
Thats my thoughts. Good forum...
The sources that were posted with regards to water requirements seem to be based on your average individual. I think it may be useful to point out that a soaking wet towel would be dry in close to 30 minutes in a pressurized cabin due to the lack of humidity. Would it not be fair to say that this type of environment can help lead to dehydration?
I am no Doctor. However, as a part-time Personal Trainer, water consumption has always been a very large part of my program, for performance and health. Since people on the average tend to have difficuly in consuming even small amounts of water, wouldn't it be best to stay on the safe side and continue to encourage water consumption in our fellow pilots (and passengers, for that matter!)
Thats my thoughts. Good forum...
I say there boy
Join Date: Mar 2000
Location: Somewhere
Posts: 1,065
Likes: 0
Received 0 Likes
on
0 Posts
Because of seeing things like this I force myself to drink at least 1.5 litres of water a day (on top of other drinks).
I'm forever in the bl**dy toilet these days....
I'm forever in the bl**dy toilet these days....
Thread Starter
Join Date: May 2002
Location: Who can say?
Posts: 1,700
Likes: 0
Received 0 Likes
on
0 Posts
I am reliably informed that a 70kg man needs 3 litres of liquid intake in 24 hours. This does not, of course, mean coffee, tea, coke, alcohol etc. as they are all diuretics.
Less than that and, in a dry, low-pressure atmosphere you are more at risk than those with their feet on the ground of problems such as DVT (leading to possibilities of pulmonary embolism, also kidney stones (very painful!) and, possibly worse than the rest (particularly for people like me!) generally poor mental functioning, poor concentration etc.
Mainly, the requirement is to be sensible about it. Drinking nothing but coffee on a 10-hour trip don't qualify!
Less than that and, in a dry, low-pressure atmosphere you are more at risk than those with their feet on the ground of problems such as DVT (leading to possibilities of pulmonary embolism, also kidney stones (very painful!) and, possibly worse than the rest (particularly for people like me!) generally poor mental functioning, poor concentration etc.
Mainly, the requirement is to be sensible about it. Drinking nothing but coffee on a 10-hour trip don't qualify!
Join Date: Apr 1999
Location: South of North
Posts: 655
Likes: 0
Received 0 Likes
on
0 Posts
It is also interesting to note that, in general, by the time you realize you are thirsty you are already in the beginning stages of dehydration!
In the cockpit environment I always have my bottle of water nearby and take sips throughout the flight.
In the cockpit environment I always have my bottle of water nearby and take sips throughout the flight.
Jet Blast Rat
Join Date: Jan 2001
Location: Sarfend-on-Sea
Age: 51
Posts: 2,081
Likes: 0
Received 0 Likes
on
0 Posts
An expert (how expert I could not say) on the radio the other day was mentioning that "of course" the water in coffee and even beer was acceptible as part of the daily water intake. He was dismissive of the idea that it was not. I think this was something to do with the fact that most of the water is to help our waste-disposal systems, and diuretics just speed up this process, don't harm it. This fits with the data mentioned by Wayne suggesting that our basic water loss can be replaced by the water in our food. Keeping hydrated then allows us great water throughput to take away bodily waste, whether that water contains diuretics or not.
Anyway some of the data should be available to pilots or at least aviation medics. My father was involved in the sixties in experiments on dehydration, sitting for an hour at a time at high alert in a Vulcan on a hot day the crews then had their water loss measured.
Anyway some of the data should be available to pilots or at least aviation medics. My father was involved in the sixties in experiments on dehydration, sitting for an hour at a time at high alert in a Vulcan on a hot day the crews then had their water loss measured.
Thread Starter
Join Date: May 2002
Location: Who can say?
Posts: 1,700
Likes: 0
Received 0 Likes
on
0 Posts
Send Clowns, was this expert talking about aviation matters? My "personal" expert ( ) informs me that, whilst it is useful to maintain a steady throughput of liquid to keep the kidneys functioning, much of the effect of diuretics is lost since the liquid intake is lost too rapidly to replace that lost in both the bowels and by sweating. I am also assured that you can sweat a significant amount without noticing it - i.e., with no noticeable damp patches under the arm, moist brow etc.
Most diuretics (dependent on type, concentration etc.) result in a net loss of fluid in the body.
I am therefore very sceptical of the claims you heard and would suggest that water and fruit juices would also be needed to maintain best hydration.
Do we have an Aviation Medicine specialist who can assist here?
) informs me that, whilst it is useful to maintain a steady throughput of liquid to keep the kidneys functioning, much of the effect of diuretics is lost since the liquid intake is lost too rapidly to replace that lost in both the bowels and by sweating. I am also assured that you can sweat a significant amount without noticing it - i.e., with no noticeable damp patches under the arm, moist brow etc.Most diuretics (dependent on type, concentration etc.) result in a net loss of fluid in the body.
I am therefore very sceptical of the claims you heard and would suggest that water and fruit juices would also be needed to maintain best hydration.
Do we have an Aviation Medicine specialist who can assist here?
Join Date: May 2002
Location: Australia
Posts: 2,242
Likes: 0
Received 0 Likes
on
0 Posts
No Expert - but........
When I worked for HM Queen I did a bit on desert survival etc. which, of course, has a lot to do with dehydration and how to avoid it.
Salient points that I remember were that up to 90% of the water content of juice, (especially cordial but not exclusively), would be required by the body to process the sugar, (natural or otherwise), contained in the juice, leaving only 10% to cope with re-hydration.
If one is about to embark on a period where dehydration is likely, (a long flight, for example), simply sipping at water throughout the period isn't good enough.
Far better to thoroughly fill your body with water first, drink 2 to 3 litres before you start, take your body way, way above the point at which dehydration begins and then it will sink towards the dehydration threshold, all this time you are physically and mentally capable. At the first signs of thirst repeat the process.
If you simply sip at water you are going from just above to just below an acceptable level of hydration, continuously, and are continuously likely to be below par both mentally and physically.
So, sipping on its own is not good enough.
It is important to be able to recognise the symptoms of the onset of dehydration. By the time you feel light headed or your joints ache, concentration is drifting away etc. etc. it is TOO LATE, you are now considerably dehydrated. Thirst is a good pointer.
Additionally, if you notice that your urine is darker than usual and smelly then you are dehydrated.
From an aviation point of view avoiding dehydration should be quite simple, top up with water well above the 'norm' before you go and maintain a high level of hydration as you go.
Always drink water in preference to other drinks if it is available.
Ensure your company policy is to make available sufficient drinking water for the crew.
Salient points that I remember were that up to 90% of the water content of juice, (especially cordial but not exclusively), would be required by the body to process the sugar, (natural or otherwise), contained in the juice, leaving only 10% to cope with re-hydration.
If one is about to embark on a period where dehydration is likely, (a long flight, for example), simply sipping at water throughout the period isn't good enough.
Far better to thoroughly fill your body with water first, drink 2 to 3 litres before you start, take your body way, way above the point at which dehydration begins and then it will sink towards the dehydration threshold, all this time you are physically and mentally capable. At the first signs of thirst repeat the process.
If you simply sip at water you are going from just above to just below an acceptable level of hydration, continuously, and are continuously likely to be below par both mentally and physically.
So, sipping on its own is not good enough.
It is important to be able to recognise the symptoms of the onset of dehydration. By the time you feel light headed or your joints ache, concentration is drifting away etc. etc. it is TOO LATE, you are now considerably dehydrated. Thirst is a good pointer.
Additionally, if you notice that your urine is darker than usual and smelly then you are dehydrated.
From an aviation point of view avoiding dehydration should be quite simple, top up with water well above the 'norm' before you go and maintain a high level of hydration as you go.
Always drink water in preference to other drinks if it is available.
Ensure your company policy is to make available sufficient drinking water for the crew.
Last edited by BlueEagle; 29th Jul 2002 at 10:23.
Join Date: Dec 2000
Location: U.K
Posts: 139
Likes: 0
Received 0 Likes
on
0 Posts
Hi,
Just a couple of points to add,
1: I read somewhere that a 1% level of dehydration leads to a 10% loss of mental/physical performance. Plus a greatly increased risk of muscle damage etc
2: I saw a documentary on Athletes saying that they drink enough water to ensure their urine is completely clear... ie if it has any colour in it there is some level of dehydration.
Just a couple of points to add,
1: I read somewhere that a 1% level of dehydration leads to a 10% loss of mental/physical performance. Plus a greatly increased risk of muscle damage etc
2: I saw a documentary on Athletes saying that they drink enough water to ensure their urine is completely clear... ie if it has any colour in it there is some level of dehydration.
Join Date: Jun 2002
Location: New South Wales
Posts: 1,794
Likes: 0
Received 0 Likes
on
0 Posts
My first thought on reading this when Captain Stable posted it over on the Medical and Health forum was 'Uh oh, another urban myth'. The idea that 75% of Americans are chronically dehydrated is absurd.
This all feeds into people's already present anxieties and indeed the fear of dehydration and a dry throat are very common symptoms of generalised anxiety, whose prevalence has reached epidemic levels in our Western societies.
Drink as much as you need not to feel thirsty and to feel well. Don't count how much you drink or you'll become obsessed with it. There is no evidence that drinking more prevents diseases of any sort. The only time you probably want to force yourself to drink is in very hot climates when you're outside and then it can indeed be hard to keep up with fluid requirements (8-12 litres a day).
Otherwise, don't sweat it. (Pun intended.)
QDM
P.S.
This is true, but there's a significant amount of fluid in the food we eat, so it doesn't translate to 3 litres of drinking per day, unless you're not eating.
This all feeds into people's already present anxieties and indeed the fear of dehydration and a dry throat are very common symptoms of generalised anxiety, whose prevalence has reached epidemic levels in our Western societies.
Drink as much as you need not to feel thirsty and to feel well. Don't count how much you drink or you'll become obsessed with it. There is no evidence that drinking more prevents diseases of any sort. The only time you probably want to force yourself to drink is in very hot climates when you're outside and then it can indeed be hard to keep up with fluid requirements (8-12 litres a day).
Otherwise, don't sweat it. (Pun intended.)
QDM
P.S.
I am reliably informed that a 70kg man needs 3 litres of liquid intake in 24 hours. This does not, of course, mean coffee, tea, coke, alcohol etc. as they are all diuretics.
Join Date: Mar 2002
Location: The Pub
Posts: 204
Likes: 0
Received 0 Likes
on
0 Posts
Water Water!!!
I'm currently detoxing after 3 weeks of holidaying and water is one of the only things I can drink.
I can tell you I am drinking more than 3 litres a day, and sometimes not even going to the toilet at all, especially when it's hot!
Just goes to show how much the body does need - it also fills you up as well as salad is not much cop for that!!!
MORE WATER VICAR.......MINES A HIGHLAND SPRING ONE!!
I can tell you I am drinking more than 3 litres a day, and sometimes not even going to the toilet at all, especially when it's hot!
Just goes to show how much the body does need - it also fills you up as well as salad is not much cop for that!!!
MORE WATER VICAR.......MINES A HIGHLAND SPRING ONE!!