Can you eat dirt

But even so, we know very little about geophagy because for centuries scientists were stubbornly lacking curiosity about it.

The first explanation scientists have come up with to explain why hundreds of thousands of people worldwide crave and eat dirt is that there must be something useful in the clay — micronutrients of some kind.

But no dice. For starters, although the clay her study participants in Zanzibar were eating was tinged with red, 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 gave a geophagist the option of snacking on Georgia white kaolin or the reddish clay found on Zanzibar, they'll almost always pick the white kaolin, which does not contain iron.

The explanation that eating dirt is somehow protective doesn't make much intuitive sense — 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. If you'll recall from the last time you read the Bible, even the snake had to eat the dust as punishment for talking Eve into eating the forbidden apple. But clay face masks suck the impurities from your skin, and they're made of dirt, right? According to Young, eating clay might coat the inside of the gut, in much the same way a mud mask coats the face.

But why would somebody need an intestine mud mask? The answer is, protection from pathogens and harmful chemicals. Most toxins enter your body in the things you eat. You digest the food and it's absorbed through the wall of your intestine and into your bloodstream — lots of pathogens and chemicals get to us in this way, too.

Clays can bind to the mucin mucus layer inside your gut, forming a barrier. 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 for pregnant women , there's something of a Goldilocks Principle at play here: you want to shield 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 will become bound by the clay, and won't be absorbed by your gut. Although the clay might be protecting you from pathogens to some extent, it's also preventing you from absorbing the nutrients. The third explanation for why people eat dirt or clay is that it might help with nausea, vomiting and diarrhea by coating the stomach.

Joiner is describing the delectable taste of dirt -- specifically, clay from the region around her home in Montezuma, Ga. While most people would recoil at the thought of eating mud or clay, some medical experts say it may be beneficial, especially for pregnant women.

The habit of eating clay, mud or dirt is known as geophagy. Some experts lump it into the same category as pica, which is the abnormal urge to eat coins, paint, soap or other non-food items. Cultures worldwide have practiced geophagy for centuries, from the ancient Greeks to Native Americans.

In most places the habit is limited to women, especially women who are pregnant or of childbearing age. The practice is common in sub-Saharan Africa, and many anthropologists believe geophagy was brought to the United States by African slaves.

It is now most commonly found among African-American women in the rural South. Though the practice is rarely if ever recommended by medical professionals, some nutritionists now admit the habit of eating clay may have some real health benefits.

David L. Clay's ability to absorb plant toxins is well documented. Diamond notes that many traditional cultures cook food like potatoes, acorns and bread in clay as a way of protecting against the toxic alkaloids and tannic acids that would otherwise make these foods inedible. Glycoalkaloids, for example, are commonly found in potatoes and can cause diarrhea, vomiting and neurological problems in humans. But when South American Indians eat these potatoes in combination with alkaloid-binding clays, the potatoes are safe to consume, according to Diamond.

Medical professionals studying geophagy are also considering whether the minerals in some clays are especially beneficial for pregnant women. It may simply be that women who had this craving were more likely to survive and pass on this tendency to their offspring.

Mineral content in clays vary from region to region, but many contain high levels of calcium, iron, copper and magnesium. Clay, like kaolin, seems to be the kind of soil people crave to eat the most Credit: Sera Young. Studies of animals suggest an adaptive, biological explanation could be at least part of the story. When elephants , primates , cattle , parrots and bats engage in geophagy, for example, it is generally considered to be serving a useful purpose. Despite this, some of the same scientists who consider geophagy normal in animals still see it as abnormal in humans.

Undoubtedly some cases of dirt eating do indeed involve psychiatric problems, but drawing a line is difficult. In , the US Agency for Toxic Substances and Disease Registry concluded that pathological levels of soil consumption constituted more than mg per day, but even they conceded that this was an arbitrary measurement. Clearly there are downsides to consuming dirt. The presence of soil-borne diseases and toxic substances in the clay is a major issue, as is the possibility that the very deficiencies supposedly cured by the practice might even be caused by them.

Eating dirt can even become an addiction, an impulsive act hidden from others. To fully grasp this phenomenon, and understand whether its effects are positive, negative or a subtle mix of the two, researchers need to undertake hypothesis-driven tests that take both biomedical and cultural factors into account.

If you liked this story, sign up for the weekly bbc. Share using Email. By Josh Gabbatiss 16th June The practice of geophagy — eating earth — is surprisingly common, and while in some parts of the world it is regarded as an eating disorder, in others it is actively encouraged.

Sheila was a child in Cameroon when she first got hooked on kaolin. These non-food cravings happen a lot, and they happen right under our noses — Sera Young. I wondered what it is that gets so many people hooked. Instead of an illness, is geophagy a treatment?