The nutritional and health benefits of drinking urine are majorly debated. Let's run through the process. You consume things and the stomach breaks them down into its composite parts and runs them through the liver. The liver emulsifies the fats in food, filters out impurities and passes waste to either the bowel or to the bladder.
The excess liquid waste is stored in the bladder in a watery substance. This is then passed out of the body as urine.
In one litre of urine you'll find
9.3g of urea
1.87g of chloride
1.17g of sodium
0.75g potassium
0.67g of creatinine
and various trace compounds
In terms of it's hydration, it does have a high concentration of salt. Not as bad as seawater which is 35 gallons per litre, but it still has a very high 3g/L.
To break that down a bit futher (no pun intended) let's have a look at what those substances do:
Chloride, Sodium and Sodium Chloride
...can all be found present and correct. Sodium chloride is of course common salt, but all chlorides are corrosive, and this is what makes seawater (and urine) so bad for you. It is the chlorides in seawater that cause corrosion to ships, cliffs and everything else.
Potassium
is necessary for all living cells to operate. It is no surprise it is found with sodium and sodium chloride as up until the 1700-1800s, we thought that Potassium and Sodium salts were essentially the same thing. It took a hundred years (1807) to prove otherwise.
It is however a metal, and quite a reactive one. It has one more electron than argon (which is very stable - a noble gas) and thus is likely to use that electron to react with things. When you cut potassium (which you can do like a knife through butter, it's very soft) you find that it's silver and quickly begins to taint into a grey colour, like an apple.
It was discovered so late that it doesn't even have a real Latin name. Before we had the strict naming convension (established by the International Union of Pure and Applied Chemistry in 1918) we could name things what we liked. Now we stick to a -ium format. Potassium's Latin name is Kalium (which is why its atomic symbol is K), however in English we call it Potassium because of the use of "potash," which is heavy in Potassium and has been used for 1500 years for soaps, bleach, fertilizer, fuel and nowadays, aluminium recycling and electroplating. Ever since Latin began its decline in the Renaissance, we've had to keep making it up to keep its medical and scientific usage relevant.
It is a fossil fuel and was previously mined like coal, but in the modern day we can manufacture it.
Urea
Is used to process nitrogen in the body. Mitochondria (little bugs that live in your body) and cytosol (the liquid inside cells) send it through a series of five processes to turn the nitrogen in your food into stuff the body can use to grow, and the waste is put out of the body. Now urea is odourless, colourless, tasteless and neither acid nor alkaline, but it does react very strongly with water. It is this reaction to water that produces the ammonia that makes urine pungent.
It can be used to make explosives, plastics, reduce pollutants in diesel fumes, and get this... it is the flavour enhancer in cigarettes, a colour enhancer in pretzels and the active ingredient in hair removal creme and tooth whitening paste. It's also used in moisturisers and hair conditioners. Yuck.
Sterile?
Now everyone knows that urine is sterile. Well, it mostly is. It is because it's produced in isolation inside the body after all the body processes are done with it. But bear in mind that bugs, rods and cocci live on *any exposed external cells* and as a result are likely to be caught and dragged in as urine leaves the body.
Maybe it's for this reason that the US state of Oregan recently dumped 32 million litres of water because someone urinated in it and was caught on CCTV. This wouldn't happen in the UK because all of our freshwater reservoirs are covered. However, no one could adequately explain why the US wasn't worried about animals and other pollutants getting into the constantly exposed water system.
What they should have done is followed one of Phil Mann's Full Mind's handy tips for purifying water:
Solar
This is one of the most easy methods to do. What you need is a 2 litre coke bottle (or similar plastic), fill it with contaminated water and leave it in direct sunlight for 6 hours, or for 2 days if there's a lot of cloud cover. The sun's rays will naturally kill anything nasty living inside.
Boiling
Thoroughly boiling something can rid it of any nasties.
Chlorine
Add 8 drops per gallon.
Charcoal
Burn wood and use water to keep it from burning too hot and decaying in the flame. It will leave you with charcoal. Crush and stir this into water. Filter. Repeat these steps twice. Mix it with clay from a riverbank. Allow it to settle overnight. Drink the clear water off the top.
Plant Sunflowers
This is if you've got a lot of time and need to purify a large area, but it is especially useful in a post-nuclear apocalypse as it soaks up nuclear impurities as well.
Mix it with Pure Water
If you have a limited supply of fresh water and it's running out - say you're stuck at sea, you can mix 1/3 seawater with 2/3s freshwater to eek out your supply a little more.
So What Are The Benefits Then?
Well to get to the point, you can use it in the following ways :
As Toothpaste
In Ancient Rome and Gaul they did this. The Roman poet Catullus writes:
Dentes tui sicut levia sunt
Ut hoc vos plenius indicat urincam
So the fact that your teeth are so polished
Just shows that you're all the more full of piss
What a joker.
As A Cure For Everything
There have been many quests for a panacea (a cure-all). However there is literally no scientific basis for any of these claims. Any claims that people have made that says that drinking their own urine cures colds/cancer/headaches/broken bones are made despite the fact that science can't prove them right.
As A Cure for Tiredness
Now here's an interesting thing, again pretty unprovable, but they are saying that if you're feeling jetlagged your first wee in the morning contains a higher concentration of the hormone melatonin, which helps regulate sleep patterns, and could help you feel like you've had a longer sleep than you've already had.
It's up to you to experiment and get back to me on the results.
For Jellyfish stings?
No. It does nothing. If you've been stung by a jellyfish and had someone wee on your leg it was all for nothing. In fact it may have made matters worse.
Jellyfish stings are like microscopic bear traps (called cnidocytes). When you press on them it sets them off - which is how they work when you're stung by them. By weeing on them, there will be no chemical reaction to help the pain, and the physical pressure/action of the liquid on your leg may cause undetonated sting cells trapped in your skin to go off.
For sexual practices?
Sure. Whatever floats your boat. Although you're in good company with the porcupines. The male will wee on the female in order to soften her quills for an easier ride.
Because the Bible tells you so?
Well there's the disputed verse in Proverbs 5:15: Drink water from you own cistern, running water from your own well. Is this a divine message about autourine therapy? It could be. Or it could also literally be saying, "Drink water from your own cistern (not someone else's, that's theft), drink water from your own well (not someone else's well, that's stealing)." Or another interpretation could be "Drink water from your own cistern, i.e. your wife, don't hang around with slags."
If you're stuck in the mountains
Bear Grylls has achieved internet infamy for drinking his own wee in his TV show. However, if you find yourself in that position you could always try this:
Wee in a saucepan or pot. Cover it with some kind of waterproof material, with something small in the middle to create an indentation. Underneath this indentation, also in the pan you place a smaller cup. The heat will evaporate the water from your urine, it will condenstate on the material, run down the underside of the indentation and drip into the small cup. Enjoy...?