Ground Yourself: The Story of Soil Eating

This is an article I wrote for InTandem, the magazine for Tandem Festival, in celebration of soil and its role in our environment and culinary culture. Find out more about Tandem here
You can have it baked, fried, sun-dried, smoked or raw. Some have described it as ‘ripe for the eating’. What is this food that I am referring to? 

Soil. Obviously.

eating soil
Would you like a side of dirt with that?
Patrick Holden of the Sustainable Food Trust referred to soil as the land’s ‘internalised gut’, drawing parallels between the role of microbial activity in promoting a healthy topsoil and a healthy digestive system in our own bodies. However, let’s move beyond simply drawing parallels – what about the evidence of eating soil for stomach health?
The deliberate ingestion of soil, or ‘geophagia’, is a practice that is jeopardised by our increasing detachment from the land and our reliance on processed foods and big retail, eradicating all crumbs and dirty smears from our foods. It is also subject to exoticism. Even within academic literature, geophagia is framed as odd, perverted and strange; clustering it within a psychological banner of pica, or the conscious act of eating non-edible things such as ice, metal and glass.
With a history that dates back 2 million years to our ancestors Homo Habilis, and a geography that stretches from southern United States to southern Asia, the rich stories behind geophagia need to be told.
Rather than stigmatise it, we need to socialise soil eating in all its muddy glory.

 “They crave that mineral”

Initially, the main accounts of eating soil were linked to slavery and extreme malnutrition; eating dirt was simply a means to fill your stomach and stave off hunger. This practice, while rare, still occurs in acutely impoverished communities. For example, in 2009, the National Geographic reported that Haitian slum dwellers resorted to eating “cookies made of dried yellow dirt…salt and vegetable shortening”.

Even outside of acutely food impoverished communities, accounts of geophagia exist, suggesting that eating dirt is not simply a means to fill one’s stomach, but could have nutritional or cultural significance.  

Daphne Lambert recently published a book Living Food: A Feast of Soil and Soul, documenting the benefits of eating soil for health. In particular, clay-based soils can provide minerals such as calcium, sodium and iron, helping alleviate anaemia and support energy production.

One example is ‘white dirt’, or kaolin. Now predominantly used to make paper and paint, kaolin was introduced to the American South during the trans-Atlantic slave trade. Despite the slave trade being abolished, geophagia lives on, with the documentary Eat White Dirt’ depicting local communities selling kaolin in ziplock bags at flea markets for medicinal and weight loss purposes.

white dirt kaolin
White Dirt in all its dirty glory

A ‘mud mask’ for your gut?

Another reason for eating soil is linked to its role in immunity. Early records from Mesopotamia and ancient Egypt describe ingesting soil for medicinal purposes, including soothing chronic gastroentinal and dermatological conditions.

Research has found three dominant soil eaters, or at least those who crave soil: young children, pregnant women and individuals living in humid environments.  Context matters, however, and factors such as climate, culture and tradition interplay throughout. For example, only 0.01% of pregnant women in Denmark crave dirt when they are pregnant, compared to 30-60% of women in Tanzania. Soil cravings are so prolific amongst pregnant women in the Tiv Tribe, Nigeria, that it is seen as a sure sign of early pregnancy.

But, there are common strands throughout. All three demographics are more susceptible to pathogens; whether it’s through playing in the dirt, having a supressed immune system, or living in climate conditions that are more prone to airborne and waterborne disease.

What has soil, containing over ten billion bacteria per tablespoon, got to do with this? Clay-like soils in particular could help protect you against harmful pathogens.

The reason for this is that the negative charge of clay molecules binds to positively charged pathogens such as E Coli and Vibro cholerae. In the same way putting soil on oil spills helps to soak up the oil, a similar ‘mopping up’ of toxins occurs in our gut. Clay is also sticky, forming a layer over the mucus lining between our gut and the blood stream, preventing pathogens from entering the latter.

However, this ‘mud mask’ also can prevent the absorption of beneficial minerals such as iron, zinc, potassium and mercury, leading to deficiency. There is also evidence of environmental contaminants and toxins, both from natural and anthropogenic origin, resulting in health risks such as tetanus, cancer and hookworm disease.  Ultimately, the link between soil eating and human health is one riddled with trade-offs and complexity.

My treat: Soil as a side dish

So, while gorging ourselves on copious amounts of dirt may not be the best idea, what about leaving crumbs of soil on our fresh fruit and vegetables? Is there any evidence to suggest that soil adds to our foods?

Adding to our vegetables?
This is the question Sabrina Krief and colleagues posed when investigating geophagia amongst chimps, our closest animal relative. They found that chimps frequently ate soil alongside plants with anti-malarial properties. Without the ingestion of soil, these plants would be toxic and rejected by the digestive system; the soil essentially acts as a gateway to accessing the anti-malarial benefits. The same has been seen amongst Australian aboriginals, using clay-like soils when cooking with carbohydrate rich tubers which, if eaten alone, would cause severe diarrhoea.

While medicinal benefits may be enough of a reason to incorporate soil into culinary practice, taste and locality also play a role in its acceptance. For example, in the Americas, indigenous cultures used clay to neutralise bitter foods such as acorns and potatoes; it is simply an additional benefit that clay also helped to remove toxins such as glycoalkaloids, commonly found in potatoes. 

Similar findings were found by Sera Young, a member of the Division of Nutritional Sciences at Cornell University. Analysing 480 records of geophagia, she noted that 98% prefer clay soils, with an affinity for the taste of soils close to their homes. One excerpt from the American South states:

Williams’ mother and father only eat clay harvested from their childhood homes. They don’t have the right type of dirt in Laurel…so today her parents hold out for the red dirt of their hometowns and indulge in the treat when visiting their families”

This notion of soil being a ‘treat’ is something to reflect on. 

It takes 500 years to create just one inch of topsoil; a precious resource that provides a nexus between culinary culture, environment, health and tradition. Next time you walk through the fields, remember the parallels between your own digestive system and the soil underneath your feet; say thank you to the crumbs clinging to your seasonal produce; and by all means, just go eat dirt.

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