Humans have been eating dirt for as long as we’ve been eating—well, pretty much anything. Evidence of geophagy (that’s the name of the practice) reaches back at least two million years, to when Homo sapiens were still Homo habilis. They loved it. Old mate Hippocrates, the 4th century BC Greek physician widely considered the great-grandfather of medicine, was the first to record the phenomenon, writing "if a pregnant woman feels the desire to eat earth or charcoal and then eats them, the child will show signs of these things.” This appeared in a textbook between 460-377 BC.
Across the millennia, geophagy has been most commonly linked to pica: the urge to consume non-nutritive substances. In line with Hippocrates' observations, pica is most commonly experienced by pregnant women or people with dietary deficits. It’s reasoned that women eat dirt because the body’s mineral requirements are increased during pregnancy.
But dirt eating has also long been tied to a bunch of other health benefits. A few centuries after Hippocrates called it, he was backed up by science writer Gaius Plinius Secundus sometime between 23 and 79 AD. Gaius was a big fan of alica, a cereal that contained clay, which he praised as offering a: “soothing effect… as a remedy for ulcers in the humid part of the body such as the mouth or anus. Used in an enema it arrests diarrhoea, and taken through the mouth… it checks menstruation."
Much of this has been lead by Dr. Josh Axe, doctor of natural medicine, clinical nutritionist and founder of a popular self-titled natural health website. He’s the author of Eat Dirt, The Real Food Diet Cookbook and Eat Dirt: Why Leaky Gut May Be the Root Cause of Your Health Problems and 5 Surprising Steps to Cure It.
Dr Axe is a big fan of soil‐based organisms, which he believes support gut health and immune response by nourishing cells in the colon and liver and kill bad bacteria. Unfortunately, according to him, our modern sanitisation of food—i.e. washing our vegetables—has destroyed our contact to these organisms. In a perfect world, he suggests you try consume 500 milligrams of dirt a day by buying produce from farmers markets and not over-washing it.
He’s not alone in his thinking. In 2011, The Quarterly Review of Biology reported research from Cornell University that found eating dirt could protect the stomach against toxins, parasites, and pathogens. Although it was also found that in many cases, eating dirt messed with the absorption of food into the bloodstream through the gut—which could lead to more nutrient deficiencies.
But things are looking a little better for dirt’s most elegant cousin: clay. In her book Craving Earth, nutritional anthropologist Sera Young describes clay as a natural filter, explaining it can act like a “mud mask for the gut.” She explains that it works by binding to harmful chemicals, and exits the body before entering the bloodstream.
Nutrition expert at the Yale School of Medicine Dr. David L. Katz echoed the theory when speaking to ABC News, saying, "It is possible that the binding effect of clay would cause it to absorb toxins."
Once again, there is a historical precedent for this, beyond Gaius’s gross sounding cereal. Cultures from around the world have reported eating clay as a way to manage nausea—especially when it comes to morning sickness. Pregnant people love dirt. More recently though, pharmaceutical companies have used kaolin clay to make Kaopectate—an ingredient in many diarrhoea medications.
Now, not everyone is on this dirty bandwagon. Eating clay has been known to cause constipation. And for all the good dirt promises, there can be a lot of downsides too. Beyond the aforementioned issues of interfering with nutrient absorption, dirt is also—well, filthy.
The majority of dirt we’re in contact with each day can be full of bacteria, worms, viruses, animal feces and parasites. It can also cause electrolyte disturbances and intestinal obstruction. In a 2002 article on the history of earth eating in the Jornal of the Royce Society of Medicine, the authors warn that it can also lead to perforation and peritonitis. And while cases of this are rare, the mortality rate among them is high.
So if you’re keen to try this out for yourself, you might consider opting for a supplement like shilajit, which is a natural substance found in the Himalayas that the National Center for Biotechnology Information describes as being “formed for centuries by the gradual decomposition of certain plants by the action of microorganisms.“ Or if clay is more your style, seek out edible kaolin from a health food shops. Just go easy on it, and don’t get too backed up.
Wanna go deeper into the stranger corners of the wellness industry? Check out our series Well, Thank U