Silly science and the drinking of urine

June 4, 2014

A friend sent me the following link, having remembered my outdoor education comments that urine was generally sterile, and did not require any particular precautions in the backcountry:

There are two parts to this story, one which is simply a bad interpretation of mediocre science and the other of which is a genuinely stupid concept which seems to have some traction.

First things first: the bad interpretation of mediocre science.

The article refers to a study presented at a recent medical meeting which actually had nothing to do with the outdoors; it was a study of the urine of women with overactive bladder. The investigators used what was described as a “cutting edge” method to show that most urine contained bacteria, even if this could not be shown by the conventional method (growing actual bugs from the urine). The method (hardly “cutting edge”–it’s been around for years) actually involved identifying not bacteria themselves but rather traces of their genetic material, DNA. This is the same methodology which is used in forensics to identify suspects from traces of their body fluids.

What the investigators actually showed, therefore, was not that bacteria were present in some urine samples but that traces of bacterial DNA were present. There is a big difference. This method is so sensitive that it can identify the most miniscule of traces of bacterial DNA. Such material is probably all around us–any living thing can leave such “fingerprints”.

When we talk about something being “sterile”, we do not mean the absence of tiny amounts of genetic chemicals. We mean the absence of viable bacterial which can grow according to usual laboratory methods. Isolated fragments of DNA cannot reproduce, grow, or cause disease. Thus, the absence of bacteria growing in standard culture from urine indicates that the urine is “sterile”, in spite of any “cutting edge” DNA findings.

So, the thoughtful, environmentally sensitive camper can continue to relieve himself or herself in the North American wilderness without fretting about spreading disease. Some have argued that the concentrated salts of urine could have unpleasant environmental consequences, damaging flora or attracting animals. This may or may not be a concern. If it is, however, there is an easy solution: pee in streams or other bodies of water! Heresy, eh?

Now for the genuinely stupid concept.

Apparently, there is a thread in some circles which promotes the drinking of urine as a health or survival technique. According to the Outside article, the media’s favorite spokesperson for this is apparently a dude named Bear Grylls, who has some sort of reality show Man versus Wild. In one segment, he is shown in a very hot, dry desert, extolling the benefits of drinking urine as a way of maintaining hydration.

The Outside article used the above study showing urine was “unsterile” as a way of criticizing Grylls. The problem with the technique, however, has nothing to do with sterility. It shows an incredible lack of understanding of basic human physiology.

The role of urine is to concentrate and excrete salts in the diet as well as the break down products of protein digestion. Drinking urine may supply one with some water, but it also puts right back into the body the salt and waste products which are contained in the urine. These have to be excreted again, but will require more body water in order to make the urine to excrete them a second time. Thus, drinking urine actually worsens dehydration, even though it puts a bit more fluid into the body.

This is pretty basic science. It was shown most elegantly by a chap named James Gamble, who in the 1940s did very careful studies designed to create the optimal life raft ration. Taking anything other than plain water clearly made one’s hydration worse. Of course, it was “reported” even earlier by Samuel Taylor Coleridge in The Rime of the Ancient Mariner: “Water, water everywhere, but not a drop to drink.”

I guess that Bear Grylls doesn’t read romantic English poetry.