Drinking blood

I am just wondering. Let’s say the blood is perfectly clean (no aids or anything) could it be lived off of? It has water and all the good stuff in it right? How would you consider it for comparison versus drinking a soda? Would the blood type matter?
I am just curious, im not planning to drink any blood.

Vampires drink blood. The Maasai have survived on a diet of blood and milk and then there is black pudding and similar foodstuff so why not?

The biggest problem with blood is that it contains a lot of fat. If you ate large amounts long term you;d end up with all the health problems associated with a high fat diet.

Just a WAG, but I should have thought that it might be rather too salty be used as your only source of water, rather like drinking seawater. Also, it will not have any dietary fiber.

Vampire bats are presumably specially adapted to live on a blood only diet. Humans are not. The Masai certainly do not live on blood alone, and neither have I heard of anyone living on nothing but black pudding.

I would like to see a cite on the fat issue, though. Sure, it is going to have some fat, but is it really dangerously more fatty than the average modern American (or European) diet?

Blood is isotonic with blood, rather unsurprisingly.

Would it be possible to sustain yourself on blood for a short amount of time in an emergency situation?

I would imagine so.

Though there is the whole issue that some people have a nausea reaction to swallowing blood [like from a nosebleed] that I am not entirely certain is from the squick factor. Isn’t there something about large quantities of the iron in heme causing nausea?

So what? The body is adapted to drinking water and other fluids less salty than blood, and then it excretes water faster than salt to bring up the level of the blood’s saltiness. If you drink nothing but blood, you will be getting a higher proportion of salt to water than you normally do. Maybe it is not more than the body can handle, but that does not follow from the fact that blood is isotonic with blood.

If you’re looking for volunteers…

I think it would probably be fine for a short term emergency, but if it was someone’s only source of nutrition long-term then I think there would be a risk of iron overload.

The body has an extremely well-tuned set of mechanisms to preserve salt and water balance, which can cope with a huge variety of situations. It can be overwhelmed, but as long as the kidneys, adrenals and pituitary are functioning correctly, it takes a very extreme situation. As long as the person is getting enough water to survive, I doubt the kidneys would have any trouble excreting any unnecessary sodium.

I’ve never heard this. Bone marrow, where blood is made, *is *high in fat, however.

The only reason it’s better to drink things less salty than blood is because we get so much salt in our diets. If you manage to cut out all sodium, potassium, chlorine (chloride?), and calcium from your diet, you would die from a lack of electrolytes if you only drank water (unless it was a VERY mineral-y mineral water.)

A famous nephrologist did an experiment (back in the 40’s or 50’s, possibly on himself, cause that’s how those rockstar researchers did shit in the glory days) where he compared the rate of urine production right after drinking distilled water vs isotonic saline.

Very, VERY quickly after ingesting a large quantity of distilled water, a large volume of urine was produced, because the water diluted the blood and feedback mechanisms that are in place detected this, and the excess fluid was gotten rid of.

With the large amount of saline, the urine was produced much more slowly, because while it was still the same amount of excess fluid, it was isotonic and it didn’t cause those same feedback mechanisms telling the body that the fluid had to be gotten rid of right away.

So, to summarize, blood would be perfectly fine to drink and really wouldn’t give you any “excess” salt if it was your only source of nutrition, assuming it was fairly close to isotonic when it was colelcted (I suppose if the person/animal was very dehydrated or had blood that is naturally hypertonic compared to a human’s, then yes, it wold be too much salt.)

Except that we know a person can’t live on seawater as their water source. So it’s not THAT hard to get to a situation extreme enough for death. It seems at least a reasonable question whether blood is too salty.

Sure blood is pretty much isotonic to blood, so there’s no immediate effect on bloodstream sodium concentrations from drinking a tall glass of the red clotty stuff, but humans lose lots of water just from breathing and perspiring, so the body is going to need to get rid of sodium even on a no-salt-added all-blood diet. I guess it comes down to whether the kidneys can concentrate sodium into urine enough to excrete all the sodium in the water lost for respiring and urinating.

Of course that depends on how much sodium is in the drinks. Quick Googling seems to show seawater is about 0.47 mol/l in Na, while blood is 0.130 mol/l, so nearly four times less concentrated. [If any med students want to correct me, please go ahead]

I’m no physiologist, but if I had to bet, I’d guess blood is survivable (from a salt-balance perspective), unless there’s a lot of perspiring going on, in which case I’d get more worried. But at any rate, we’re talking about less than a factor of four less than a clearly deadly level of sodium, so I don’t think it’s a ridiculously clear answer either way.

There’s something about this thread that’s causing nausea. Bleah.

I seem to remember learning that the Mongols used to drink blood from their horses when food supplies got low. The horses had plenty of grass to eat and so could withstand a few cups being let. Not sure where I heard this but it seems reasonable.

Yes, iron can upset the stomach to say the least. It’s a side effect often of Iron Pills.

Yes, it does follow from that fact.

Just think about it for a second. Your kidneys are trying to produce a filtrate at exactly the same concentration of water and salt as the liquid that you are consuming. They aren’t trying to concentrate salt, they aren’t trying to excrete excess salt. They are trying to produce exactly the same balance as in the original liquid.

So then ask yourself: how can this possibly be *more *salt than the kidneys can handle? And the answer of course is that it can’t.

It necessarily follows that an isotonic fluid can’t be excessively salty. That’s what isotonic means. How else do you think it’s possible to maintain adequate hydration drinking isotonic fluids like Gatorade?

That would be true if you weren’t breathing or perspiring. But in fact you’re losing water every time you breathe out (and a variable amount from sweating). So your kidneys actually have to produce a filtrate that excretes all the salt you consume, but only excretes the amount of water left over after you’ve exhaled and perspired some of what you consumed.

If everything you drink is isotonic with (normal) blood, then you’re going to have to excrete a more concentrated solution than blood in order to stay balanced with consumption and respiration/perspiration.

(Of course, we’re glossing over questions about how well water and salt are actually absorbed by the intestines; so far we’ve kind of assumed perfect 100% absorbtion)

This overlooks the fact that other substances other than salt are being excreted in the urine, in particular urea. In the case of blood, a considerable amount of urea will be produced by the breakdown of amino acids from the protein in the cells. So in this case the kidneys will need to produce a hyperosmotic urine relative to the blood plasma in order to avoid net water loss.

Offhand, I’m not sure whether a blood diet would produce too much urea for the kidneys to deal with in humans if blood were the only source of water. Vampire bats have some peculiar physiology due to their diet. Immediately after a blood meal, they want to get rid of as much weight as possible to make it easier to fly back to their roosts. They produce a large amount of dilute urine to jettison most of the water in the blood. Back at the roost they need to digest the blood solids, but have no source of water there. They thus produce a highly concentrated urine in order to get rid of the urea.

So let me get this straight. On the issue of salt, are you people actually disputing that a perosn can stay adequately hydrated by drinking isootnic fluid? If you aren’t I’m not sure what you are disputing.