June 06, 2011
Why Do People Eat Dirt?

An important question. Do you eat dirt? Sera Young and other researchers at Cornell asked the question of why do people eat dirt? While at first glance micronutrient deficiencies might seem a plausible guess in reality the clay most often eaten is not a good source of minerals.

The nutrition hypothesis was also a poor fit to the data. The database shows that the kind of earth people eat most often is a type of clay that contains low amounts of nutrients like iron, zinc, and calcium. Plus, if calcium deficiency drove people to eat dirt, one would expect them to do it most often at life stages when they need calcium the most—adolescence or old age. But that isn't the case, according to the database. Reports do indicate that geophagy is often associated with anemia, but several studies have shown that cravings for earth continue even after people are given iron supplements. What's more, some research suggests that clay can bind to nutrients in the stomach, making them hard to digest. If that's true, it's not a lack of nutrients that causes geophagy; rather it could be the other way around.

So what is it? The dirt might be killing parasites and pathogens.

Overall, the protection hypothesis fits the data best, the Cornell researchers found. The database shows that geophagy is documented most commonly in women in the early stages of pregnancy and in pre-adolescent children. Both categories of people are especially sensitive to parasites and pathogens, according to Young and her colleagues. In addition, geophagy is most common in tropical climates where foodborne microbes are abundant. Finally, the database shows that people often eat earth during episodes of gastrointestinal stress. It's unlikely the intestinal problems are caused by the dirt itself because the type of clay people usually eat comes from deep in the ground, where pathogens and parasites are unlikely to contaminate it. Plus, people usually boil the clay before eating it.

Boiled clay? So there's a whole gastronomic tradition around clay eating.

So the thought crossed my mind: Are there clay diet cookbooks? Didn't find anything promising. But turns out Sera Young has written a Kindle book on why people have cravings for clay and a few other items.Craving Earth: Understanding Pica--the Urge to Eat Clay, Starch, Ice, and Chalk.

Any closet chalk-eaters out there? Do you eat it for calcium? To save money on Tums? Turns out the calcium carbonate in chalk comes from coccolith plankton. Ring a bell? See my recent post on the advantage that coccolith will have other other plankton as higher atmospheric CO2 increases ocean acidity.

Share |      Randall Parker, 2011 June 06 10:12 PM  Brain Appetite

Brian said at June 7, 2011 2:26 AM:

Is this part of the paleo diet? :)

Brett Bellmore said at June 7, 2011 3:55 AM:

".Craving Earth: Understanding Pica--the Urge to Eat Clay, Starch, Ice, and Chalk."

I have to admit my first reaction was, "Two of these are not like the other two."

not anon or anonymous said at June 7, 2011 6:17 AM:

In Haiti, clay is routinely eaten as comfort food. They make cookies by mixing dirt with salt, sugar and vegetable fats, then the cookies are sun-dried before eating. Quite tasty actually.

PacRim Jim said at June 7, 2011 3:28 PM:

Consumer alert!
Put dirt in your food and eat your ancestors.

frost said at June 12, 2011 3:20 PM:

I saw a talk about some Indians living in the high Andes who ate clay with their potatoes. This was not just any clay but clay of a particular texture & color from a specific site, perhaps chosen for its palatability. The presenter mentioned that one possible reason for doing that was that the potatoes they ate had high levels of the poisonous glucosides present in wild potatoes (because at such altitudes the number of edible species was very limited) and that the clay bound the poison and rendered the potatoes safe to eat.

I'm just speculating, but there may be other health related benefits of eating clay. E.g., are intestinal parasites impaired by coming into contact with (at least some types of) clay? If so, the persistence of such practices, e.g. in the US South, may be cultural.

Randall Parker said at June 16, 2011 7:04 PM:

PacRim Jim,

I see your gruesomeness and raise you: Put dirt in your food and eat your future corpse.

Jerry said at December 27, 2011 7:00 PM:

Just letting you guys know that I eat clay, first boiled in water, and it's very good for you. Things that aren't good for you are taken by the body and placed in the clay, and then the clay is escorted out of the body. Many minerals and elements come from clay, too -- the clay itself isn't always rich in special miracle particles, but it typically has plenty of good stuff trapped inside of its latices, sort of like a treasure chest. Dead plant matter is much of what makes green clay green, and iron/cobalt minerals can contribute red/pink/purplish colors to other clays. Many clays are volcanic in origin, and contain elements that scientists currently don't recognize as good for you, but they are. Clay also calms the stomach and helps the whole body to heal, and clears the mind, and cleans the organs, and for the time it's in the body it actually becomes a living part of it. Native Americans (including south america) and people from a lot of other cultures recognize clay as one of the seeds of human life, from the beginning, and it's important to them. Hope that helped!

april said at June 5, 2013 6:37 AM:

Many people eat clay and its not abnormal. Buy clay online at georgiawhitedirt.com/. They sell red and white clay from Georgia. It tastes soooo good! I eat it because I love the taste and texture as do many people of all cultures and from around the world.

gejala stroke said at August 29, 2016 8:17 PM:

Gejala Storoke ringan dan cara menanganinya secara alami harus diperhatikan selalu secara serius , karena saat ini kasus penyakit stroke banyak terjadi dikalangan masyarakat dari mulai stroke ringan hingga stroke berat.
Meski yang dialami masih gejala stroke ringan tapi penanganannya harus secara tepat karena bisa berakibat fatal jika tidak diatasi dengan obat stroke yang ampuh. Sebelum kita membahas lebih lanjut mengenai pengobatan stroke, maka kita harus mempelajari dulu tentang apa itu penyakit stroke, penyebab penyakit stroke, gejala stroke,
serta bahaya apa yang bisa muncul? Setelah itu baru kita bisa memilih obat stroke yang tepat yang akan kita gunakan.

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