What is snot? And why do some people eat it?


The Stranger's "Ask Science" column offers a detailed explanation of just what, exactly, boogers are. It is simultaneously gross and mesmerizing:

Mucus, chemically, is quite fascinating. Sugar chains are attached to a protein backbone in mucus cells, with the contraption released out into the open. These glycoprotein molecules rapidly and aggressively suck up water until they are plump, slick, and slimy. To an invader, this is a nightmare to navigate: tangled chains of protein and sugar, with every nook and cranny crammed with water molecules. (Boogers are when these chains become ever more tangled, finally resulting in a rubbery ball of partially dried-out snot. Neat!) The body adds antimicrobial enzymes to this mix, which digest the invading organisms as they slowly attempt to chew through this barrier and reach the thin underlying lining of cells.

Which reminds me: Over the years, I've stumbled across some interesting discussions about whether picking your nose and/or eating boogers is a psychological or biological phenomenon. That is, when people do this, does it reflect some kind of psychological or socio-cultural issue; or is there a biological reason why booger-eating could be beneficial? 

The truth is, there's not been a great deal of research done on this subject, at least from the biology angle. We know about booger-eating as a function of human behavioral development. There's been some research into it from the perspective of evolutionary psychology (i.e., why do people think this is gross?). But analysis of whether or not there is a biological reason people engage in booger eating has been lacking. Perhaps unsurprisingly. It would be interesting to see the responses you'd get if you tried to recruit volunteers for that study. Especially considering the fact that, as I think about it, you'd probably want your test subjects to eat both their own boogers, and those of other people, to see whether that had any impact on any presumed immune system response. 

But I digress. If you are not totally grossed out yet, I'd recommend reading "Eating Snot – Socially Unacceptable but Common: Why?", a chapter in the book Consuming the Inedible: Neglected Dimensions of Food Choice. You can read most of that chapter on Google Books. Author Maria Jesus Portalatin focuses mainly on the better documented socio-cultural implications, but gets into a bit of the biology. One thing she points out, nasal mucus is about 95% water, so there's a possibility that you might expect more mucus eating in arid places. But nobody has ever done the studies necessary to test that hypothesis out. Her main hypothesis—also untested—is that eating mucus might help prime the body's immune system, allowing it to have more contact with weakened forms of potential pathogens so it can better detect and destroy those pathogens later. In other words, she thinks that eating your boogers is sort of like self-immunization.

Blame Tim Lloyd for sending me down this train of thought.

Image: BOOGER KING, a Creative Commons Attribution (2.0) image from aroundtheway's photostream



    1. Yeah, this sums up my feelings nicely.

      “You’d probably want your test subjects to eat both their own boogers, and those of other people” This keeps looping in my head, along an image of a white-coat lab tech handing out small plastic cups filled with boogers and the ensuing consumption of said cup. Gaaaaaah!

      The I remember when I was seven and chased my baby-sitter around the house with a big, mucousy booger on my finger. I laughed then, and I laugh now.

  1. One thing she points out, nasal mucus is about 95% water, so there’s a possibility that you might expect more mucus eating in arid places.

    I assure you that, in the desert, boogers are about 0% water and sometimes have to be removed with sharp, metal instruments in order to maintain a nasal airway.  And that’s after half an hour of a cotton ball soaked in hot water being stuck up your nose to soften them up.

    1. living in canada, I moved from ontario (great lakes country) to Alberta (the plains) and in no way ever would Alberta be considered a hot province but just by not having a lake every two miles made my nose go thru the same thing you described.   I found it quite impressive if also agonizing. (dry feet too but I digress)

      1. I wear wool socks even in the summer.  Toe cracks hurt like hell.  It’s particularly bad now; the dew point was -12°F yesterday.

        1. I share your pain..:
          Avoid hot showers, use skin cleansers with lots of lanolin.  I find urea lotion helps.  Alternately, you can put gobs of wound-healing antibiotic ointment all over the cracks and cover this with gauze and tape it up – it’s give your skin a change to heal; moist wounds heal much better.

          Microplanes are excellent for removing/thinning the thick hard dead skin so that you can restore flexibility and help stop the cracking.

          1. Microplanes are excellent for removing/thinning the thick hard dead skin so that you can restore flexibility and help stop the cracking.

            It took me a while to realize that callouses would cause cracking. I use one of those Dr. Scholl’s pumice sticks. It’s made for your feet, but I end up using it on my fingertips, as well. In this weather, daily.

  2. Okay, so snot is anti-microbial. Does that mean I’m keeping myself sick longer by making an effort to keep my sinuses clear during a cold? My personal, anecdotal experience has been the opposite. (ie. letting the gunk sit in my head unmolested makes the things worse)

    1.  I think once you are sick the anti microbial functionality is basically over. At that point I was always under the impression that a runny nose and mucus production were sort of the body trying to flush out physically as much of the infection as it could. Thats why I usually blow my nose a lot and use nasal lavage to help get mass quantities of virus out of my body wholesale. I try not to over do it with the nasal lavage though.

  3. Mucus is very hard to digest (thus headcold with mucus flowing down the throat often brings an upset stomach). Drying them to boogers might make them more digestible.  Interesting at a theoretical level.

    1. Drying them to boogers might make them more digestible.

      Sweeten them, dye them hot pink and sell them as snacks.

      1. Don’t think the local Ag Dept would like that. But cow boogers might work. Oh, pork boogers!! BWHAHAHA!! I’m rich!!!


    I have two friends who do this in public and it totally grosses me out. I love my friends, but ARRRGH I wish they wouldn’t do it. It seems to be totally unconscious on their part, since they usually do it when they’re concentrating on something else.

    Nobody’s called them on it, so far as I know, because it’s far too embarrassing. I occasionally cough to let them know that someone is noticing their excavations, but neither of them has picked up on the hint yet.

    1. I bet you’re doing some or another nasty thing too when you’re letting your mind wander and concentrate on other things. Like scratching in your ears, or scratching open a wound, or peeling your fingernails, chewing on fingernails, biting bits of skin off your lip, scratching your crotch, rubbing under your armpits etc.

      We’re monkeys, just get over it, pitty we don’t do lice anymore, bad for social cohesion.

      1. Yeah… see… none of my other friends pick their noses in public. It’s just these two guys who have somehow not learned how to use a tissue. And they do it a LOT.

        1. So you’re objecting to doing it in public. By conjecture you imply they don’t know how to use tissue. Maybe they prefer it the other way and know perfectly well how to use tissue, but are unwilling to sacrifice trees :)

          I’m rather suspecting though it’s another thing. Since quite a lot of people do it, it’s safe to assume those who do it don’t find it gross. They’ve probably been doing it their hole lives, and it’s kind of unconscious, like say touching your face and mouth as most people are prone to do about every 20 seconds to minute or so.

          Actually did you know that there’s more bacteria living on your keyboard then on your toilet seat. Yet you probably rub your eyes and touch your mouth just seconds after you stopped typing something, probably also chew on the fingernails (I won’t say how many bacteria you find below fingernails).

      2. …pitty we don’t do lice anymore, bad for social cohesion.

        Don’t have any school-age children, eh?

    2. The other downside to calling them out on it is that they’ll use it against you. “Hey Amphigorey! I picked you a fresh one!” :P

  5. I used to make this dare with people:  Instead of swallowing your saliva (which most people do pretty constantly), spit into a glass for a day, and then drink it all at once.  Never had a taker…

    1. Uhm, dude. With the amount of bacteria living in our oral cavity the saved up saliva in your glass will gradually evolve into something else. I did experiments on the subject in my formative years, so I know… The smell is a dead giveaway.

  6. When I was in China, I noticed that it is fairly common to see people picking their nose, but they cover their mouth if they are using a toothpick.  It struck me as the opposite of North America.

  7. I have found it HILARious that even that the nose, throat, and mouth are connected.. and people will easily cough up a spit ball of the material that fell back out of their sinuses.. if that SAME stuff should exit out thru the nose and re-enter the mouth over the lips its then the most gross thing evar!!!!!!!!!!!!!!

  8. Why is it disgusting? Easy: if it’s expelled from the body, that means it’s waste. You wouldn’t dig a deuce out of the toilet and digest it one more time, so why would you want to take nasal waste and process it one more time?

    1. Yebbut it’s not normally expelled from the body.  In the normal run of things, cilia waft it up the nasal passages and down the back of the throat, into the digestive system.  Why worry about people delving around and putting it in their mouths, when it would have ended up in the same place anyway?

      1. Yebbut it’s not normally expelled from the body. In the normal run of things, cilia waft it up the nasal passages and down the back of the throat, into the digestive system.

        Not true. You even see cats and dogs honking it out.

  9. I played in a band with a guy who constantly picked his nose and ate them in public and did not care who saw him.  What I find weird, is how many people pick their nose in their car in public and think that they’re being blocked from view by a one-way mirror or something.

    1. Maybe being in a car is like the enhanced and modern version of being in the safety and warmth of a prehistoric cave. Makes the cultural inhibitions go away.

  10. Research has shown that children raised in sterile environments (linoleum floors cleaned regularly) have a higher rate of asthma as adults.  Babies and young children seem to put everything  they come across into their mouths.  What doesn’t fit in, they lick.  The guess is that this primes their immune systems.  So, boogers, traps for more environmental threats, could serve as mega-immune boosters.  Adults, with less active immune systems, would suffer rather than benefit from this exposure.  Encourage your kids to eat their boogers, then switch them to a snot substitute (tapioca?) when they get older.

  11. “One thing she points out, nasal mucus is about 95% water, so there’s a possibility that you might expect more mucus eating in arid places.”

    And pee drinking? It’s pretty high in water content, too.

    1.  Urine (human and other animal) drinking and using it for bathing and/or medicine is not uncommon in the world.

  12. I was a pre-school teacher.  In a couple decades I never saw a kid who didn’t do it.  Meanwhile, it takes a lot of teaching to get kids to desist and for many it highly possible what we actually accomplish as parents and teachers is getting them to be more discrete about where and how they do it.
    Personally, I think this persistent instinct is related in some way to the whole concept of homeopathy.  

  13. I happened to write the first comment in this thread.  I’m not judging anyone, seriously.  But, seeing the whole subject brought up for scientific scrutiny just somehow creeps me out.  But also somehow, I was driven to check back here 8 hours later to see the comments.  AFIC, my first comment stands.   :)

  14. Booger is picked because it causes itching. Booger is eaten because that is the most handy way to remove the very sticky booger from the finger.

    Booger management is one of the reasons why I’m uncomfortable with having a camera on me at work.

  15. When we were little kids, Mom always used to say to my sister “STOP that! Do you want me to get you a box of boogers for Christmas?”. I wonder how many parents have said this. Hmmm….I probably should buy some stock in boogers as they’re always plentiful and always in demand for one reason or another. Screw Apple stock.

  16. My 7th grade speech teacher offered to give me an automatic A if I did my final speech on mucus. A fascinating subject, I brought samples.

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