[thedoc (OP)]

If I'm walking in the desert and becoming dehydrated, would drinking wine accelerate my dehydration or would it help?  If I left the wine out so that the alcohol could evaporate, how long would I have to leave it to be safe to drink?
Asked by Simon, Hiroshima

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[thedoc (OP)]

Sue Baic, Lecturer in Nutrition and Public Health at Bristol University:

[img float=right]http://www.thenakedscientists.com/forum/copies/RTEmagicC_450px-Grapes_during_pigmentation.jpg.jpg[/img]Presumably by then you’d actually be pretty thirsty.  Your drive would be to try to drink whatever you could but actually that would be the wrong thing to do.  Any alcoholic drink over about 10% alcohol strength will actually be a net dehydrator.  This means it will cause you pass out more water in your urine than it actually gives you.  For example, for a 125ml glass of wine you’d actually end up passing 150ml of fluid so it’ll be a net loss of about 25ml of fluid.  It definitely wouldn’t be a good thing to do to drink that.  With beer, if you’re drinking full-strength beer at 5% alcohol you’ll lose about half of the water but the other half will contribute to your daily water intake.

Niall Macfarlane, Senior Lecturer, Faculty of Biomedical Sciences, Glasgow University:

The common belief that taking alcohol will lead to dehydration is pretty well-supported in scientific research.  The reason for this dehydration effect is that when the blood alcohol level rises it stops the release of a hormone called anti-diuretic hormone.  As the name suggests this hormone normally prevents urine production so when you lower its levels that leads to an increase in the amount of urine you produce.  Consequently you can get dehydrated.  However, the exact amount of alcohol that increases urine production can vary from person to person.  It’s safe to say that if you drink a lot that will always cause a problem.  I know there’s actually some use and value in that wine.  I know that alcohols are more volatile than water and that ethanol boils at only 78 degrees as opposed to 100 degrees Celsius for water.  Perhaps there’s some salvation there.  I could open the bottle of wine in the shade, even the shade from my own body, and I should be able to remove alcohol from the wine by letting it evaporate.  If you’re into cooking and you pour some wine into a frying pan then the alcohol disappears almost instantaneously.  If you’re out in the desert and you’re in the sun the temperatures could be over 100 degrees centigrade.  So if it’s anywhere above 80, 90 degrees you open the bottle and the alcohol will evaporate off within 30-40 minutes.  This would leave a liquid to hydrate and provide energy for myself.  Given that situation perhaps I could take myself to have a few glugs and get a party going.

[Ignorant Enthusiast]

It's perfectly safe to drink the wine, or coffee, or any one of the other 'unsafe' drinks.

Water would hydrate you more, but there is still more than enough water content in wine to keep you hydrated.

Wouldn't want to wake up in the middle of a desert with a hang over though !!!!

[Madidus_Scientia]

No, alcohol is a diuretic. (Something that causes dehydration)
If it was very light beer instead of wine there might have been a net gain of hydration, but for something like wine which is generally 10 percent alcohol or more, I would definitely say drinking it in an already dehydrated state would not help your chance of survival. It would be like trying to drink seawater.
Don't know how to calculate how long you would have to leave the wine open to evaporate the alcohol, but it would depend on the surface area of the wine exposed to the air, the temperature and the amount of air flow on the surface. So if you could make a small fire to boil the wine, this would accelerate your cause significantly.

[turnipsock]

If you were to leave the wine to let the alcohol evapoate, some of the water content would also be lost.

Current practise, according to Ray Mears, is to drink when you are thristy rather than ration your water. Rationing water causes organ damage so you are better to drink when thirsty. At least the wine would mean you would have a less stressful passing, it's best served at room temp btw.

The ideal solution would be to set up some sort of still and seperate the alcohol from the rest.

[neilep]

What if it's alcohol free wine ?  []

[Karen W.]

then you are in luck.. it would be better yet..

 i do agree with the new poster Madidus_Scientia.. totally..

[Bored chemist]

Water is a diuretic. Should you avoid it when thirsty?

[Madidus_Scientia]

If you take pedantically the definition that a diuretic is something that increases urine production, then yes, water is a diuretic. However in a healthy body drinking water will obviously never cause you to become dehydrated.

And i didn't mean to drink it while its boiling hot turnipsock, you would obviously let it cool down first

[turnipsock]

And i didn't mean to drink it while its boiling hot turnipsock, you would obviously let it cool down first

Actually I didn't think that, but it may be near the answer. Warm the wine to about 78.5C and that should get rid of a lot of the alcohol.

What if it's alcohol free wine ?  []

What a stupid concept.

How do they make alcohol free wine anyway? ...there's your answer.

[rosalind dna]

And i didn't mean to drink it while its boiling hot turnipsock, you would obviously let it cool down first

Actually I didn't think that, but it may be near the answer. Warm the wine to about 78.5C and that should get rid of a lot of the alcohol.

What if it's alcohol free wine ?  []

What a stupid concept.

How do they make alcohol free wine anyway? ...there's your answer.

Turnipsock I don't know how they make alchohol free wine, but I can tell you that it tastes sharp and vile.

[neilep]

And i didn't mean to drink it while its boiling hot turnipsock, you would obviously let it cool down first

Actually I didn't think that, but it may be near the answer. Warm the wine to about 78.5C and that should get rid of a lot of the alcohol.

What if it's alcohol free wine ?  []

What a stupid concept.

How do they make alcohol free wine anyway? ...there's your answer.

Gee thanks !!

[Bored chemist]

More importantly, what do they do withe the wine free alcohol?

Anyway, it seems clear to me that if the wine had a high enough alcohol content then drinking it would be a bad idea on account of its diuretic effect.
On the other hand if the alcohol content were low enough then it would be better to drink it than not. Just as a number to work with, let's say it's a rather weak wine containing 10% alcohol by volume.
If you drank, say 10% alcohol for long enough then you might supose that, in the end, you would replace all the water in your body by 10% alcohol- that would kill you. However, the body is capable of destroying alcohol by metabolising it. Typically people can metabiolise about 5 to 10 g of alcohol per hour. That's the alcohol in about 100 ml of this (rather weak) wine. Porvided you drank less than about 100 ml an hour you might be able to metabolise away the alcohol nd use the water. With a stronger wine you would need to drink less.
Also, in what people think of as a typical desert it's hot so you would need to drink a lot- that's a lot of alcohol which would be a problem in its own right. Most people don't realise that bits of antarctica are deserts too.
Now it's cold there so you wouldn't need to drink so much . I think it's possile that you might get by if the wine was fairly weak and the weather not too hot. Of course, if you are in  atntartica you haev a reasonable chance of finding water- you just need to melt it.

[turnipsock]

[Karen W.]

Water is a diuretic. Should you avoid it when thirsty?

Is it?

[lyner]

Apparently, they needed several takes for that scene. John Mills was in quite a state by the end - almost dehydrated, possibly.

[syhprum]

There is a famous historical case where the crew of the ship Medusa foundered on a sandbank and took to a raft, large quantities of wine were consumed and despite being quite close to the shore all perished.
 

[another_someone]

Actually, maybe a bit unseemly, but not unheard of - if the wine is acting as a diuretic, then could this effect not be offset by drinking your own urine?

[Madidus_Scientia]

not a pleasant thought, but interesting question

I suppose if its a matter of survival i reckon you probably could, i've noticed that after a decent amount of alcoholic beverages urine starts to become rather clear, suggesting its mostly just made up of water that the diuretic effect is making you excrete, and if you were to drink this i'd imagine it would only have insignificant amounts of alcohol in it since your body will have metabolised the bulk of it (At a maximum it could only be the same alcohol percentage as your blood, and if that was too high you'd be dead).

I think i'd try the evaporating-the-alcohol thing first though

Would humidity of the air effect the rate of evaporation of the alcohol, or just the water? (i know its probably not humid if you're in a desert, i just mean in general)

[passerby]

Yo!  Professor Macfarlane:  ...temperatures over 100 degrees CENTIGRADE in the desert...  Dude, that´s 212 degrees Farenheit and no place on earth outside a volcano has ever gotten that hot