Science Questions

Can beer prevent dehydration?

Sat, 14th Jul 2012

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Paul Winter asked:

Question: I know that alcohol is a diuretic, but if one was in a situation for example stranded at sea, where there was nothing else to drink except say beer would it be worth drinking the beer or would that just hasten dehydration.


In addition to this, sailors of old are known for their like of rum, how would this have affected their health when fresh water would have often been limited commodity.


Thanks very much, Love the show, Keep up the good work


Paul Winter

Brigg, North Lincolnshire


Diana -   Well, the answer is, yes, it probably is okay to drink the beer as long as its alcohol content is less than 10%.  So, if you're not going for the things like Special Brew and the really hardcore beers, then you're probably actually going to hydrate yourself rather than dehydrate yourself overall.  And another little tip is that if you do perhaps only end up with wine or something that does have more than 10% of alcohol in it, then maybe if the temperature is high enough, you might be able to undo the top, leave the alcohol to evaporate a little bit, and maybe reduce the overall alcohol content.  You might have something – well, it won’t be very nice to drink.  It might save you, you never know.

Chris -   So there's a threshold concentration at which we think there's a beneficial effect of about 10%.  Beyond that, people are going to dehydrate net, but they’ll have some fun under that then probably, you'd be okay to drink it and it will do you a benefit.

Diana -   Yeah, that seems to be the case.  And also, a little factoid, in the medieval period when freshwater was just so horrible to drink, everybody used to drink small beer which was very low alcohol beer.  Obviously, they didn’t all become desiccated and dried out like prunes, so it must've worked.

Chris -   I remember, when reading archaeological texts and things, you see that the people building Hadrian’s Wall, for example, were given a ration of beer every day and it was largely all that was being served.  I remember thinking when I was little, “Gosh!  Weren’t these people permanently drunk?”  But it’s because the alcohol content was low.

Diana -   Yes, that’s right.


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Hi Paul

we looked into this as a "Question of the Week" in 2008; in short, it depends upon the alcohol concentration. Beverages containing less than 10% alcohol have a net hydrating effect. Here's a link to the answer.

Chris chris, Sun, 15th Jul 2012

headache from hangover is due to dehydration of the water around the brain, i read, so a good midnight hi quantity gulp of water in the middle of the night helps with the morning after. CZARCAR, Sun, 15th Jul 2012

Mild dehydration is common and usually caused by not drinking enough fluids throughout the day. Fluids are continuously lost through normal body functions such as sweating, breathing and urinating. Common causes of dehydration include gastrointestinal water loss caused by diarrhoea and vomiting, excessive urination, excessive water loss through the skin (sweating) and lungs (breathing) due to heat and/or humidity, physical activity and fever or burns
julyfer, Fri, 17th Aug 2012

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