Why Do Some People Eat Dirt?

The craving for and practice of eating earth is more widespread than you might think. Learn why researchers think people engage in pica (a.k.a geophagy) in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff production of I Heart Radio, Hey
brain Stuff Lauren Vogel Bomb. Here in gas stations and
flea markets all around southeastern United States, you can find
packets or boxes containing crumbles of white clay. In Kenya,
you can buy reddish dirt on the street, formed into
little pellets that look like baby carrots. In Uganda, you

(00:23):
can buy Yankee Doodle brand dirt at the grocery store.
A website called Earth's Clay Store sells clay from all
over the world and ships them right to your home.
But what are you supposed to do with it when
it gets to you, Well, you eat it. You might
have a vague sense that you've heard of people eating
dirt before pregnant women. Maybe Pika is the overarching term

(00:44):
for craving and eating things that are not food. In
the sixth century CE, the physician Flavious Asius noticed people
sticking non food items in their mouths the way that
magpies pika in Latin pick up random objects in their beaks.
He figured these people had entirely indiscriminate app types for
just any old thing, and termed the behavior after the magpie.

(01:04):
It turns out pika is kind of a misnomer because
pike A cravings are actually very specific, though according to
the Diagnostic and Statistical Manual of Mental Disorders, or d
s M, it includes a range of behaviors. Some people
crave paper clips, batteries, or coins. These potentially dangerous cravings
are considered by the d s M to be actual disorders,
but pika can also include cravings for raw starch that's

(01:27):
am allophagy, ice that's patofgy, and dirt that's geophogy. Geofogy
is one form of pikea found in almost every country
in the world. We spoke with Sarah Young, assistant professor
in the Department of Anthropology at Northwestern University. She said,
I was surprised when I first saw it. I was
studying pregnant women ethnography in Zanzibar, and I asked a

(01:48):
woman what she ate when she's pregnant, and in Swahili,
she said, every day, I take earth from this wall
and eat it. I was just learning Swaheli and was
pretty good at it, but I really didn't think I
was understanding correctly. My research assistant was like, yeah, you
heard right. Young ended up writing her PhD dissertation on
geofogy and winning the Margaret Meat Award in for her

(02:09):
book Craving Earth, which detailed her research about geofogy practices worldwide.
In her research, Young tracked down medical literature, historical texts,
research on animal behavior, soil science, in parasitology, and came
to the conclusion that there are four possible explanations as
to why people eat dirt. The most common and longest
running take on geofhogy is that there's no good reason

(02:31):
for it, that it's a pathology, it's an aberrant behavior
of some unknown origin. Young explained the racism, sexism, and
classism behind that simplistic take quote it's the women they know,
not what they do explanation. It was basically white men
writing about this for the past few hundred years, and
it was dismissed as aberrant. We can refute this. There

(02:52):
are so many species of animals that go to great
risk to get clay and charcoal, like the colobus monkey
that steals charcoal from villagers. But even so, we know
very little about geophogy because for centuries scientists were stubbornly
lacking curiosity about it. When scientists did start looking into it,
the first hypothesis they came up with to explain why

(03:12):
hundreds of thousands of people worldwide crave and eat dirt
is that there must be something useful in the clay,
micronutrients of some kind. Young said, the mother Nature's multi
vitamin explanation is a really intuitive one, but unfortunately it
doesn't really shake out for starters. Although the clay her
study participants in Zanzibar were eating was tinged with red,

(03:33):
indicating iron content, investigations into whether that iron could be
absorbed and used by the body came up empty. Plus.
According to Young, people generally prefer whiter clay. If you
give a geophogist to the option of snacking on Georgia
white kalin or the reddish clay found on Zanzibar, they'll
almost always picked the white kalin, which does not contain iron.

(03:55):
So we turned to another hypothesis. Could dirt provide protection
from germs. The explanation that eating dirt is somehow an
immune system boost might not make sense on the surface.
After all, we're supposed to stay away from dirt, wash
our hands, clean our clothes, take off our shoes when
we enter the house. But clay face masks can draw
germs and oils and dead cells from your skin, and

(04:17):
they're made of dirt right. According to Young, eating clay
might collect stuff inside of the gut, similar to how
a mud mask collects stuff from your face. But why
would somebody need an intestinal mud mask. The answer is
protection from pathogens and harmful compounds. Many harmful microorganisms and
compounds can enter your body via the things you eat.

(04:38):
You digest the food and it's absorbed through the wall
of your intestine and into your bloodstream, but lots of
potentially harmful stuff can get to us in this way too.
Clay may stimulate the mucus membranes on the surface of
your guts to create more mucus, thus forming a sort
of protective barrier against those pathogens and compounds. Young said,
it can also bind with whatever harmful thing you're eating.

(05:00):
For example, in the Andes, people eat wild potatoes which
contain these toxic chemicals called glycoalkaloids, but after they dip
the potatoes in clay, they become safe to eat. But
while eating clay might protect from pathogens and harmful chemicals,
which is especially important in pregnant women, there's something of
a Goldilocks principle at play here. You want to shield

(05:20):
yourself from the harmful stuff, but you also don't want
to protect yourself from the nutrients you need. For example,
if you eat a steak that's full of both bioavailable
iron and pathogens, but you eat clay at the same time,
the iron could also become bound by the clay and
wouldn't be absorbed by your gut. Although the clay might
be protecting you from pathogens to some extent, it's also

(05:40):
preventing you from absorbing the nutrients. The fourth hypothesis for
why people eat dirt clay is that it might help
with nausea, vomiting, and diarrhea by coating stomach. After all,
a number of anti diarreal treatments have kalin in them.
Kalin puts the KAO in kaopectate. Though the reasons for
geofogy are still rather mysterious, Young stresses that it's far

(06:02):
more common than we realize, partially because of those old
stigmas against it. Young said, people don't like to talk
about it or admit it. When I'm doing ethnographic interviews,
I always ask how much Earth do you eat? Instead
of do you eat earth? Because so many people have
sworn they don't eat it and later tell me that
they do. But they lied because I didn't want you
to think I was poor. Today's episode was written by

(06:29):
Jesse and Shields and produced by Tyler Clang. Brain Stuff
is a production of iHeart Radios How Stuff Works. For
more on this and lots of other food for thought,
visit our home planet, how stuff Works dot com, and
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