Drinking urine
From BearWiki
Claim: Drinking your own urine is just plain stupid, and a good way to cause yourself to die of dehydration.
"That's horrible. There's no getting away from it. It's warm and pretty salty." -- Bear Grylls
In the Kimberley, Australia episode, Bear drinks his own urine to avoid dehydration and cites an anecdote about some sailors who did it and survived. This is stupid and dangerous. Small amounts of urine when you have other sources of hydration are not very problematic (some view it as medicinal[1]), but the fact is that your body is getting rid of urine for a reason.
As Bear notes, urine is 95% water. However, most of the rest is salt mixed in with various toxins; the salt component is about 2%[2]. About 0.3% of the human body is dissociated sodium+chlorine (table salt), and all salts combined leave it still below 1%.[3] Due to osmosis, water travels along a diffusion gradient across cell membranes to try and dilute salt. In other words, if you drink salty water (seawater, blood, urine), you are drawing water out of your cells and dehydrating them. The kidneys *can* remove salt from the system (into the urine, of course), but they can only do this at a limited rate. Seawater has a similar saline content to urine, 2.6%[4] (although some sources say as much as 4%[5]). You'll never find anyone advising that you drink seawater, and neither should you drink urine.
This ignores all of the toxins your body spent effort trying to dispose of in the urine, all of the damage the re-ingestion is doing to your kidneys, and perhaps most importantly, the major amount of water loss should the ingestion of urine cause you to vomit.
From the US Army Field Manual 21-76, Ch. 6, in the Do Not Drink table:[6]
"Urine: Contains harmful body wastes. Is about 2 percent salt."
From the SAS Survival Handbook How to Survive in the Wild, in Any Climate, on Land or at Sea John Wiseman 2004 Harper Collins, p. 494:
"DO NOT drink urine."
From Dr. William Elfarr, Urologist and former president of the Texas Urological Society:[7]
""In general, it is not beneficial to ingest one's own urine during times of starvation and/or dehydration. The urine at those times is concentrated with high sodium, other electrolyte and mineral content. This is counterproductive when one is dehydrated.""
From Master Sergeant Gary L. Benton, survival instructor to B-52 crews:[8]
"Finally, a few things you should not do. Do not drink urine. It is a waste product of a body and is just that, waste (think about that for a second…when a body passes urine, it is not longer need or useful). Drinking urine can even make you sick."
From Tom Brown Jr., survivor school founder and instructor [9]
"Don't drink urine (unless you've first purified it by means of a solar still) because doing so will increase your body's rate of dehydration. "
From Equipped.com, a survival site:[10]
""Never drink blood or urine. They will only hasten dehydration."
From Adventure Sports Online's 5 basic survival tips:[11]
"Never drink urine."
From the USGI Canteen Group:[12]
"Also, don't drink urine or sea water. Some folks say that it's saved their lives, but there is no evidence to back this up. Both contain high levels of toxins that cannot be filtered out except by distillation or reverse osmosis"
From Wildernesssurvival.net, prominently in the "Remember!" section:[13]
"Do not drink urine."
Bear cites the case of three Mexican fishermen who were lost and supposedly lived off of turtle blood and urine. This claim seems to have been pulled from thin air. The fishermen reported drinking rainwater, not blood and urine[14]:
"We ate raw seagulls, ducks and fish. We ate everything raw - any fish that came near the boat we grabbed it and gulped it down," Jesus Vidana told Televisa channel in an interview late Tuesday.
"We drank rain water because it rained every day," he said. "Twice we almost sank. The waves washed into the boat and we thought we were going to die."
Even if they had also drank blood and urine (which seems to have been reported nowhere but Man vs Wild), they're drinking freshwater, too. Small amounts of urine, while of questionable health benefit, won't kill you. But they won't hydrate you, either.
[edit] Analysis
Oppose: Les Stroud has drunk his own urine on many occasions.
Support: Les Stroud has NOT drunk his own urine. Rather, in the desert episode, he distills the water from the urine and drinks the water from the resulting condensation -- he explicitly states the risks of drinking urine without proper filtration. As the various quotes above demonstrate, drinking urine especially while dehydrated is an extremely bad idea.
