All You Need Is Blood...Blood Is All You Need?

September 10, 2007 10:48 AM

[family squabble filter]: My brother is convinced that a human could survive by consuming nothing but blood from other humans. I want to prove him wrong without actually testing his theory.

My brother and I tend to argue. A lot. And I tend to be right. Once he was convinced he had disproved the Monty Hall Problem in five minutes, because "it had to be 50%."

Anyway, his current hypothesis is that a human being could survive by consuming nothing but human blood. He thinks that since blood carries all the important things a body needs to survive throughout the body, then it must contain every thing the body needs. So, according to him, all the nutrients, vitamins, etc, a body would need could be found in blood.

I know he's wrong, but my scientific knowledge is limited to playing with corn starch and water. So, I don't have the skills needed to, once again, prove him wrong.

So, I ask of you: is there anything a human would need to survive that could not be acquired by drinking blood? Alternatively, is there anything you could overdose on if you were to consume nothing but blood? Or is my brother, for once, correct?

posted by duckierose to health & fitness (21 comments total)

Well, it's pretty well-known that lying on your back while you have a bad nosebleed can cause you to swallow enough blood to make you sick and vomit. I suspect you'd have a hard time drinking enough blood to sustain yourself before regurgitating it.
posted by TheNewWazoo at 10:53 AM on September 10, 2007

Fat-soluble and lymph-soluble vitamins aren't free-flowing in the blood. Your brother would die of a potassium deficiency (as well as deficiencies of vitamins A, D, E, and K), unless he decided to take the vampire-zombie route and eat brains as well.
posted by tehloki at 10:53 AM on September 10, 2007 [4 favorites]

Unless the blood somehow carries enough Vitamin C you will get scurvy. Scurvy won't outright kill you but it will make your existence pretty dreary and wish you weren't surviving.

Overall I would imagine it would matter how good the blood is from your source. Drinking blood from sick people may not be good.
posted by JJ86 at 10:56 AM on September 10, 2007

I remember something saying that it took slightly more water to digest blood than you get from it. So you'd die of thirst sooner or later. Here's a source. You can find more with a google of "survival drinking blood."
posted by cowbellemoo at 11:06 AM on September 10, 2007

Iron overdose would be a problem.
posted by Steven C. Den Beste at 11:08 AM on September 10, 2007

I'm fairly sure that most of the problems with this "living on blood" model are the fact that we're assuming one has to consume it orally. If one could hook one's veins up to the circulatory system of another living creature, it would be possible to survive much longer. Of course, the problems discussed above (with the vitamins and water) would kill you eventually.
posted by tehloki at 11:12 AM on September 10, 2007

Well, it's pretty well-known that lying on your back while you have a bad nosebleed can cause you to swallow enough blood to make you sick and vomit. I suspect you'd have a hard time drinking enough blood to sustain yourself before regurgitating it.

And just reading this thread makes me want to regurgitate a little bit (ok, a lot).

Besides, what's the definition of survive? Perhaps you could survive for days, weeks, months, years? I could survive on eating chocolate for quite a while. Do you mean just live every day as you would normally as you do now only "surviving" on blood with the expectation of the same quality of life that you enjoy now?
posted by Sassyfras at 11:12 AM on September 10, 2007

Iron overdose is a problem even for people who receive too many transfusions.
posted by Steven C. Den Beste at 11:15 AM on September 10, 2007

I think there are a lot of nutrients that don't travel through our bloodstream which we need. And what about fiber? You need some roughage for sure.

Also, now that you've got some real answers, I just want to add - be NICE to your brother! :)
posted by SassHat at 11:27 AM on September 10, 2007

With nothing but blood in your digestive system, fiber wouldn't really help anything. You'd have your black, rock-hard bowel movements more regularly, but you'd still be dying.
posted by tehloki at 11:51 AM on September 10, 2007

There are phlebotomy fetishist out there and I saw a presentation by one who also liked to drink blood. She was quite clear that drinking more than a small amount is extremely bad (puking, etc, all noted above). Also, it tends to clot once removed from the body unless you take extra measures like a blood bag or adding anti-clotting agents (which apparently taste bad) so drinking it from a glass just wouldn't work.

You see the strangest things at Burning Man.
posted by chairface at 12:02 PM on September 10, 2007 [1 favorite]

Remind your friend that in addition to being the principal highway for nutrients, the blood is also the principal highway for metabolic wastes. The ammonia content of blood, just for one thing, would make you vomit it up long before you could drink enough of it to give up other food. As someone else pointed out, you'd need more water to digest blood than is actually in it - hydrolysis of proteins and carbs takes a lot of water.

Cooking Blood sausage makes it more edible. I would not be surprised to learn that you could live for quite a while on blood sausage and water.
posted by ikkyu2 at 12:29 PM on September 10, 2007

What do the Masai whose diet includes a lot of cow's blood do?
posted by i_am_joe's_spleen at 12:43 PM on September 10, 2007 [1 favorite]

And I'm sure water would be allowed in his diet.

The vomiting, scurvy, and iron overdose are exactly the ammo I need.

Sassyfras, I think he meant survival as in fully functioning as he is now.

And, on a nicer note, normally my brother and I get along quite well. I have a feeling we both enjoy these ridiculous arguments almost as much as I enjoy winning them.
posted by duckierose at 12:49 PM on September 10, 2007

On a related note, Irish athlete Mick Murphy used to drink cows blood as part of his training regimen. Seemed to work, he's arguably the greatest cyclist ever.
posted by ReiToei at 1:12 PM on September 10, 2007

In a nutshell: just because something contains nutrients, you can't assume you can digest it.
posted by amtho at 1:21 PM on September 10, 2007

(in Ireland)
posted by ReiToei at 1:34 PM on September 10, 2007

I also think the blood would likely clot in your stomach. I've read a lot of hospital reports (not in the medical field or anything but have gone over a lot) and I've seen "coffee ground" vomit being noted more than once in ER reports.
posted by whoaali at 3:04 PM on September 10, 2007

I think there are a lot of nutrients that don't travel through our bloodstream which we need

Really? Then how do they get from the intestines to the rest of the body?
posted by DarkForest at 3:29 PM on September 10, 2007

I am joes spleen, the Masai also drink a lot of milk and eat some meat from their cattle.
posted by Kololo at 4:19 PM on September 10, 2007

What do the Masai whose diet includes a lot of cow's blood do?

Actually they mix cow blood and milk and ferment it. I guess that does something important.
posted by atrazine at 12:32 AM on September 11, 2007