After hearing about how much blood people typically donate, I took to wondering if someone stranded in the desert without water could “harvest” their own blood and drink it to stay alive. Does anyone know if, or under what circumstances, it would be possible to drink one’s own blood instead of water? I know a few of the factors one would have to consider(the salt content of plasma, the equipment needed, etc) but don’t know how they fit into the big picture. Any ideas on whether a group of people could share blood are also welcome.
It won’t work for one person. Although blood is in large part water, you can’t set up a cycle in the way you suggest. The water you lose as blood will have to be replaced, plus a little bit to run the processes that replace the blood. If you were to drink someone else’s blood, that might work, but you couldn’t simultaneously lose blood yourself.
Unless you can be a vampire, I guess, in which case, be most of what you can be. From the US Army Survival Manual:
Blood: Is salty and is considered a food; therefore, requires additional body fluids to digest
So, no, don’t drink blood. So says the Army.
I’ve sometimes wondered quite the same. Not about drinking your own blood (obviously one need an external contribution), but about drinking animal’s blood.
My understanding is that you can’t drink sea water, since it contains too much salts and you would need more water to eliminate them than you just ingested.
On the other hand, I read that some nomadic tribes used to drink the blood of their horses in desperate situation. I assumed for quite a long time it was only some kind of legend, but more recently, I found some references to this practices that let me suspecting it could be true.
Finally, my understanding is that the salts content of blood is roughly similar in quantity with the salt content of water.
So, there must be something wrong in my assumptions. Since I’m pretty certain one can’t drink sea water, I suspect that either :
-No tribe ever used to drink its mounts blood in case of need.
-The salts content (in quantity, not in nature)of the blood isn’t similar to the salts content of sea water (hence blood could be drunk)
-The fact that one can’t drink sea water isn’t related to its salts content (but I can’t think about another reason).
Anybody has a take on this?
Just to add that when I’m speaking about tribes drinking blood in case of dire need, I’m refering to people lacking water, not food.
(though of course they could have actually drunk blood when they lacked food and other people could have wrongly assumed that it was to replace water. But it’s not what I read)
You’re right about the salt content. The osmolarity of sea water is about three times that of blood. Most of the osmolarity of both is due to salt. Look at this site, which has a lot to say about why you can’t drink sea water, but nothing about drinking horse blood.
According to Marco Polo (OK, so probably a load of BS), Mongol warriors nourished themselves on their horses’ blood.
http://www.coldsiberia.org/monmight.htm
http://www.globaled.org/nyworld/materials/mongol/Howdid2.html
As I understand it, they would travel with 2 or 3 horses.
They also wore silk underwear! :eek:
They drank water too, I guess. In answer to the OP, it’s hard to believe that blood can serve as a substitute for H2O. Surely, you need fresh H2O to thin the blood, so it can carry on transporting wastes and nutrients around the body.
Some people believe that early south american people traveled by (really big) raft to some pacific islands. The trip was recreated a few years ago using material only available to the early people. IIRC The problem is they could not carry enough water and rain was not enough either to make the trip (which was a one way trip). They guesses that the early people speared fish and hung them up and cut cavities in them. The cavities would fill w/ lymphatic fluid which was drinkable.
I checked your link. Hmm…Assuming that horse blood has the same osmolarity than human blood, it would mean that you could use blood without your cells losing their fluids. So your body could use the water contained in blood without adverse consequences? Or would your body need to evacuate more water (to get rid of the salts contained in blood) that the blood ingested contains?
Which is similar to my original question, but I didn’t know that the major issue with salted water was the osmonis, not the necessity to evacuate the salts. Without the osmosis problem, blood could be a somewhat satisfying fluid, perhaps?
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I’ve heard that if stuck in the desert you could drink your urine for water because it is sterile. I know that it is sterile, but what about salt content? Does anyone know if this is true?
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Humans require about one and a third liters of water to concentrate in the urine the salt contained in 1 liter of sea water. So when you drink a liter of sea water, the net effect is that you lose 0.3 liters of water.
Blood is only about a quarter as salty as sea water, so it should take about a third of a liter of water to flush out of the system the salt in a liter of blood. Blood is a little more than three-quarters water, so the net effect (in theory) is that you should gain more than half a liter of water by drinking a liter of blood. This ignores all the other things in the blood that have to be excreted through the kidneys which may require more water.
Many aquatic mammals can safely drink sea water, since they have large and specialized kidneys that can excrete saltier urine than humans can. In practice, they usually get their water from their food, which is often less salty than sea water.
When I had an operation that caused bleeding into my mouth, the nurses in the recovery room gave me a suction device (like the ones used by dentists) and instructed me to use it to suck the blood out of my mouth. They warned me that swallowing the blood would make me sick. Later they told me I was the only patient they’d ever had who didn’t vomit from swallowing too much blood. I have also heard other people say that they have vomited after swallowing blood.
Now, I know that there are some cultures where people regularly drink the blood of animals. There are also blood fetishists who regularly drink human blood. I can believe that the latter may not care if it makes them physically ill, but I doubt the former would go on if it always made people sick. Could it be that drinking human blood makes people sick, but drinking animal blood does not? Is there some way the blood can be prepared that keeps it from making people sick? Or is the very idea that swallowing blood causes vomiting merely a medical UL?
I don’t know for sure that blood can’t make someone ill, but I doubt it.
For instance, AFAIK, drinking blood was prescribed in the past (say, the beginning of the XX° century) for medical reasons (don’t know in which cases, sorry) Slaughterhouses would provide it, or more exactly, IIRC, the patient would go to the slaughterhouse to have his “pint of blood”.
Also, eating blood is quite common. British black pudding, french boudin and german blood sausage are basically cooked blood (and it’s pretty good, if you ask me). Of course, cooking it could destroy whatever thing which would make someone ill…(so that would answer to one of your question : cooking blood is a way to prepare it that keeps it from making people sick. I can testify it)
Are you sure that people woudln’t vomit only because they’re disgusted by it? Also, it seems to me that some people would drink salted water if they want to vomit for some reason. Perhaps drinking salted liquids tends to cause vomiting. It would makes sense, after reading the previous posts in this thread.
Swallowing your own blood can irritate your stomach and make you vomit, but I don’t think it hurts anything beyond that. I think the same would be true for uncooked animal blood, but I’ve never tried it.