Do You Spit or Swallow? (What to Do with Your Snot)

Toddlers eat their boogers and old men tend to spit out giant wads of snot, but what about you? Do you spit or swallow your snot? Whatever your preference, scientists and doctors have some interesting opinions on the subject. Understanding what mucus does in the body — and what it can indicate about your health — may help you feel better about this admittedly gross subject, but ultimately whether you spit or swallow is up to you.

What is mucus?

We’ve all heard about mucous membranes. Parts of our anatomy with canals that lead to the outside of the body — the mouth, nose and stomach — all secrete mucus through mucous membranes. Mucus serves as the oil that keeps the machine of our bodies moving. It prevents germs, dirt and other pathogens from building up in the body. One of the functions of mucus is to trap particulate matter so it doesn’t reach the most sensitive organs. It may be sticky and slimy, but mucus is one of the ways your body protects itself from the outside world.

According to WebMD, mucus contains antibodies “that help the body recognize invaders like bacteria and viruses.” It also contains enzymes that kill pathogens trapped within it. When we’re healthy, we produce up to one and a half liters of mucus every day. In spite of what it may seem like, when we’re sick, we don’t actually produce more mucus, the consistency has just changed. So the question then is this: Is it better to spit or swallow extra mucus?

Spit or swallow?

Snot and boogers tend to really gross people out, and with good reason: they can indicate illness. It can also be inconvenient to carry a wad of tissues around with you when you’re feeling unwell, which is certainly a case in favor of swallowing your snot.

According to the Western Washington University Student Health Center, “It is no problem swallowing mucus/phlegm. It happens all the time unconsciously, and is simply protein that is digested.” It doesn’t make an illness worse and can’t hurt you, so there’s really no reason not to swallow it, but it seems that people aren’t all that convinced.

A reader recently asked BBC Focus magazine if it’s harmful to swallow your phlegm. In reply, the author pointed out that pathogens caught in mucus you cough up “have just come from your lungs where they already had almost direct access to your bloodstream.” If you swallow mucus, it’s highly unlikely that anything could survive the acids in your stomach.

The hygiene hypothesis

In fact, it might even be healthy for you to swallow your snot — or at least eat your boogers. That’s right: a Canadian biochemist proposed the idea while teaching a group of bored students in one of his classes at the University of Saskatchewan. Dr. Scott Napper specializes in emerging diseases and vaccines and found that snot and boogers really intrigue first-year students. The casual question also turned out to be an important one.

“I’ve got two beautiful daughters, and they spend an amazing amount of time with their fingers up their nose,” Dr. Napper told CBC News in Canada. “And without fail, it goes right into their mouths afterwards. Could they just be fulfilling what we’re truly meant to do?”

As gross as it sounds, Dr. Napper may be onto something. Mayo Clinic physician, Dr. James T. C. Li, M.D., Ph.D, noted that children who grow up in rural areas surrounded by a number of allergens from animals and plant life — as well as kids who grow up in larger families — tend to develop asthma less often than kids who grow up in a more sterile environment. Dr. Li refers to this in terms of the hygiene hypothesis.

The hygiene hypothesis proposes that through exposure to microbes and illness early in life, the growing body learns the difference between substances that are harmful to the body and those that trigger asthma, a rather scary allergic reaction. Through exposure to a wide variety of allergens and infections, the immune system becomes stronger. Dr. Li notes that not every infection or microbe is a good thing, however. Many of them, such as the respiratory syncytial virus (RSV) may actually cause asthma, instead of preventing it. More research is needed to help bolster the hygiene hypothesis, but it presents a good foundation for future studies.

Dr. Napper of the University of Saskatchewan points out that eating boogers fits into several other hypotheses about immunity. “From an evolutionary perspective, we evolved under very dirty conditions and maybe this desire to keep our environment and our behaviors sterile isn’t actually working to our advantage,” he said to CBC News. Dr. Napper is in the process of developing a study to investigate his hypothesis, and it sounds like just the kind of gross study that would fascinate his freshman students.

Your snot can tell you if you’re sick

spitorswallow_640x359A runny nose or a couple of sneezes doesn’t mean you’re sick. Generally, it takes an allergen or a bad cold to kick your mucus membranes into overdrive, but certain foods can do it too. According to WebMD, “During an allergic response to an offending trigger, such as pollen or ragweed, mast cells in your body squeeze out a substance called histamine, which triggers sneezing, itching, and nasal stuffiness. The tissue of the mucous membranes starts leaking fluid, and your nose begins to run.” This reaction is something we’ve all experienced, but can you really tell the difference between an allergic reaction and an illness?

It turns out that the color of your snot can indicate a number of things. According to the Cleveland Clinic, doctors rarely use the color of your snot as a primary diagnosis for illness, but it can help them understand what’s going on in your body. Here’s what the various colors of your snot could mean:

Clear: Clear snot indicates that you’re well. It’s made mostly of water, but also contains dissolved salts, antibodies and proteins.

White: White snot means you’re congested. “Swollen, inflamed tissues in your nose are slowing the flow of mucus, causing it to lose moisture and become thick or cloudy,” according to the Cleveland Clinic. If you’ve got white mucus, watch out — it might be the sign of an impending cold or infection.

Yellow: If your snot is yellow, infection-fighting cells may be engaged in an effort to combat an infection. Yellow snot includes white blood cells that fend off illness, and these cells are responsible for the yellow tinge.

Green: If your snot is green, you’re probably feeling pretty gross. It could be a sign of a bacterial infection, like sinusitis. The presence of green snot shows that your body is fighting hard for your wellness.

Pink or red: Pink or red snot indicates the presence of blood. It could be from a nosebleed or from cold weather. Keep an eye on the situation.

Brown: Brown snot usually indicates the presence of either blood or something inhaled, like a dark spice at dinnertime or some dirt while out at your favorite sporting event.

Black: “If you’re not a smoker or user of illegal drugs, black mucus may mean a serious fungal infection,” according to the Cleveland Clinic. These infections tend to occur in people with compromised immune systems who are probably already under the care of a doctor. If your snot is black, and you haven’t seen a doctor, you should.

The verdict

So when it comes to snot, what should you do, spit or swallow? There’s not a lot of evidence either way, and doctors tend to recommend doing what feels best to you. We are continually swallowing mucus anyway, and have been doing so for millennia, which is probably why scientists haven’t studied it much. We are interested to see what results Dr. Napper’s future booger study will yield, but if you value your social life, we don’t recommend eating boogers in public.

What are your thoughts on spitting or swallowing snot?

—Megan Winkler

Megan Winkler is an author, historian, Neurosculpting® meditation coach, certified nutritional consultant and DIY diva. When she’s not writing or teaching a class, Megan can be found in the water, on a yoga mat, learning a new instrument or singing karaoke. Her passion for a healthy mind-body-spirit relationship motivates her to explore all the natural world has to offer.


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