Urine: It’s Not Just For Breakfast Anymore

April 23, 2011 in Medicine by RangelMD

Popular Science decided to take a look at the ever “popular” topic of auto hydration reclamation accompanied by a disturbing not-going-to-be-seen-in-any-children’s-book-on-animals-anytime-soon picture of a Giraffe displaying the activity in question.

Obviously, there are no known health benefits to consuming one’s own golden excretions despite the very many claims otherwise.  Not only is there no hard scientific data for any health benefits but urotherapy doesn’t make sense physiologically. The main roles of the kidneys include the regulation of total body water, electrolyte balance, and pH balance. The kidneys also metabolize a multitude of difference substances and get rid of the resulting metabolites by secreting them into the urine. In short, the kidneys get rid of what our bodies don’t need or could be harmful. How could consuming what our bodies have disposed of be considered to be beneficial? Somehow, and without any legitimate scientific investigation, new age health gurus quacks believe that they have stumbled upon something that Mother Nature overlooked after hundreds of millions of years of evolutionary fine tuning. Not likely.

Now there are no known benefits in the context of normal kidney function and normal hydration. But what about consuming one’s own urine to fend off dehydration in the event you find yourself in the middle of the desert or in the open ocean without any other water source? Urine is usually made up of 95% water so logic would suggest that re-consuming this fluid that would normally be lost would be a survival benefit. In a situation where total water intake falls below 500 milliliters (mls) per day, the kidneys respond by secreting less water and making more concentrated urine.  However, the kidneys are only able to concentrate urine up to 1200 milliosmols per kilogram body weight and need to produce 500 mls of urine a day to get rid of potentially dangerous excess electrolytes and toxins. Even if your water intake is zero, you still need to make about 500 mls of urine per day to survive.  Your body needs a daily source of at least 500-600 mls of water to survive otherwise you go into kidney failure and die.

If you simply drink the 500 mls of urine that you normally produce in a no water intake situation then maybe you can delay the onset of kidney and other organ failure from severe dehydration. The problem is that your body loses water via routes other urine. Under the best of conditions the body normally loses up to 1100 mls through breathing, sweat, and in the feces. In a desert or open ocean situation these losses would be even more.  So even if you were able to safely re-consume your urine every day you would still be behind a significant amount in body water loss. Eventually, severe dehydration and cardiovascular collapse would result.

Additionally, the very concentrated urine would have a higher than normal amount (by volume) of electrolytes and other chemicals that could be harmful if re-consumed. After all, these are excess salts and toxins that the body is desperately trying to rid itself of and you want to put them right back into it!  Oh, but what if you are able to distill your urine to remove most to the harmful substances? After all, the International Space Station has a complex system in place to re-claim water from urine and other sources and turn it back into drinking water. In the event that you are able to set up a urine distillery in the middle of nowhere while facing severe dehydration you would still not be able to replace the water lost from breathing, sweat, and in the feces . . not unless you happen to be in possession of a Fremen Stillsuit.

Basically, there is little scientific data for any significant survival benefit in the event that you are dehydrated and lack access to a drinkable water source. There may be a survival benefit in theory but it is likely to be very small; on the order of a few extra hours. And even this benefit might be canceled out by the consequences of the re-consumption of excess amounts of salts and toxins in the urine. Basically, it’s better to spend your remaining energy on trying to find a water source than on efforts to drink your own urine with or without distilling it first.

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