Why Pregnant Women Eat Dirt: Benefits Of Geophagy
As a child, most of us at some time or another probably made mud pies or dirt tortillas. The ability to take a bit of soil, add some water, and begin to shape that soil into a delectable smorgasbord of imaginary food items is one of those universal childhood games. We probably also received a firm scolding from our mothers when one of those imaginary tortillas or mud pies made its way into our mouth. According to several recent studies, however, perhaps parents should have second-guessed their futile attempts to keep their children from eating dirt. Around the world, geophagy, or the practice of eating dirt is not just the result of childhood games, but rather a widespread and surprisingly common cultural practice. Across the African continent, kaolin clay sourced from termite mounds is sold in markets. Up to 30 grams of clay is regularly eaten, especially by pregnant women. According to one analysis, the rates of pregnant women eating soil or clay range from 28 percent in Tanzania to up to 65 percent in Kenya.
In this short article, we explain the cultural and historical roots of geophagy, take a quick look at the potential health benefits of geophagy for pregnant women and children, and then turn to some recent studies on how increased exposure to the myriad microbial life in the soil might be beneficial for our overall health.
Why Do So Many Cultures Eat Dirt?
The practice of geophagy has been found by researchers on every human-inhabited continent. While eating dirt or clay is currently practiced by certain groups around the world, anthropologists have found a higher incidence of geophagy in the tropics. Today, the idea of eating dirt is often derided and explained as an anti-hygienic practice affecting poorer communities where poor nutrition has led to high levels of anemia. While many types of soil do have high levels of iron and can thus help with anemia, clay soils in particular offer several other potential health benefits.
One study looking at the process of geophagy in animals found that “clays can bind mycotoxins (fungal toxins), endotoxins (internal toxins), manmade toxic chemicals, and bacteria, and they can protect the gut lining from corrosion, acting as an antacid and curbing diarrhea. In short, clay is an extremely useful medicine.” Furthermore, free-range cattle (like deer and other wild mammals) are known to regularly dig and lick at subsoil clay. This has been shown to improve food intake and increase feed conversion efficiency.
Many indigenous cultures around the world most likely included certain types of soils and clays in their diet as a cultural response to a lack of certain vitamins and minerals in their traditional diets. In various cultures around the world, children and pregnant women are the two main groups that tend to most commonly practice geophagy.
The Health Benefits of Geophagy for Pregnant Women and Children
Sera Young, the resident geophagy expert at Cornell University, has studied the practice of eating dirt in different cultures around the world. In a recent article published by the BBC, Young tells the following story about her fieldwork in rural Tanzania: “I was conducting interviews with pregnant women about iron deficiency anemia…I was sitting on the floor of this woman’s house, and I asked her what she liked to eat during pregnancy, and she said: ‘Twice a day, I take earth from the wall of my house and I eat it.’”
Iron-deficiency is a serious problem faced by pregnant women around the world. According to one study by the World Health Organization (WHO), up to 42 percent of pregnant women have been found to suffer anemia, and over 60 percent of this anemia is assumed to be due to iron deficiency. Iron deficiency, however, does not just affect pregnant women in low-income developing countries. More than a third of expectant mothers could be at substantial risk of suffering from pregnancy complications such as miscarriage or preterm birth due to iron deficiency. While almost all pregnant women in developed nations regularly take iron supplements as part of their prenatal vitamin package, women in other parts of the world might be forced to get the necessary iron from the soil. Furthermore, while the mineral makeup of the soil will differ from area to area, common minerals in the soil include high levels of calcium, copper, magnesium, iron, and zinc; all of which are critical for developing fetuses.
Geophagy in pregnant women and pre-adolescent children might also be a cultural response to protect these vulnerable populations from damage from parasites and other pathogens. In areas where damaging foodborne pathogens are common, certain types of clay can have a soothing effect on the stomach and can protect pregnant women and children from parasites and viruses. Because the clay is sourced from deep in the ground and because it is usually boiled before eating, there is a limited possibility that the clay could be contaminated with pathogens.
Young says that “children and pregnant women are two groups that might need extra nutrients or protection against disease, as their immune responses are weaker,” which is one of the main reasons for this widely disseminated cultural practice.
Increasing Our Exposure to the Microbial Life of the Soil
Just one teaspoon of healthy and productive soil contains at least between 100 million and 1 billion bacteria. Furthermore, that teaspoon of soil most likely also contains several yards of fungal filaments, several thousand protozoa, and scores of nematodes. The soil beneath our feet (or beneath the concrete of our cities) is an entire universe teeming with life and vibrancy. Unfortunately, our modern-day society has for some reason gravitated towards an unwarranted fear of the unseen worlds of microorganisms.
Today, our schools, offices, homes, restaurants, and even the food in our refrigerators more closely resemble an aseptic surgical room than the swarming abundance of creepy, crawly life in a teaspoon of soil. In an attempt to create a world where we are supposedly free from contamination caused by harmful bacteria, viruses, or other microorganisms, we have also eliminated the most important bacteria and other elements of microbial life that we depend on for healthy lives. Less than 1 percent of the different types of bacteria have the ability to make people sick, and even then, a robust immune system should be able to protect your body from infection from the vast majority of these potentially pathogenic bacteria. Of the remaining 99 percent of the bacterium, many are absolutely essential to help our bodies digest food, destroy disease-causing cells, and give the body needed vitamins and minerals, among other important functions.
Recent studies are discovering that thorough exposure to the beneficial microbes and bacteria present in the soil and the surrounding natural environment can play an extremely important role in the mental and physical health of children (and yes, that might include occasionally letting your child “eat” a bit of dirt).
Christopher Lowry, Integrative Physiology Professor Christopher Lowry at the University of Colorado at Boulder, recently participated in a study titled “Identification and characterization of a novel anti-inflammatory lipid isolated from Mycobacterium vaccae, a soil-derived bacterium with immunoregulatory and stress resilience properties.” The study, published in Psychopharmacology Magazine, discovered that one type of soil bacterium (Mycobacterium vaccae) had anti-inflammatory, immunoregulatory, and stress resilience properties. When this common soil bacterium was injected into rodents, it was shown to alter behavior in a way similar to that of antidepressants. The soil bacterium also had long-lasting anti-inflammatory effects on the brain. Lowry and other researchers involved in the study hoped that this could lead to a potential “vaccine” for trauma and stress-related disorders, such as posttraumatic stress disorder (PTSD).
Instead of waiting for a stress vaccine fabricated from the soil to become available, simply spending more time getting dirty in nature— or practicing geophagy— might be a major contributor to improved health. Back in 1989, David Strachan proposed the hygiene hypothesis, which suggested that the increasing rates of allergies like asthma were caused by a reduction in exposure to the germs. Strachan argues that families with fewer children, limited exposure to animals (such as on a farm), and more rigorous standards of aseptic hygiene and cleanliness were also responsible for this rise in allergic diseases.
In the two decades since this hypothesis was published, however, researchers are finding that it is not a lack of exposure to disease-causing germs and bacteria causing problems to our immune systems, but rather a lack of exposure to the vast majority of advantageous and health-enhancing microbial life present in the soil and surrounding natural environment.
Another Casualty of the Agricultural Revolution?
The Environmental Protection Agency (EPA) finds that the average American spends about 90 percent of time indoors. The remaining 10 percent of time outdoors is most likely spent on chemically-soaked and microbial-dead lawns, concrete or asphalt pavements, or playgrounds where even wood chips have been substituted for rubber surfaces made from ground-up tires. Whereas the majority of our grandparents spent long hours of their day playing in the mud, cleaning up cow manure from the barn, and helping their families tend to the farm or garden, most people today have virtually zero contact with the thriving microbial world found in fertile soil.
Lowry believes that “as humans have moved away from farms and an agricultural or hunter-gatherer existence into cities, we have lost contact with organisms that served to regulate our immune system and suppress inappropriate inflammation.” This fundamental demographic change puts us at a much higher risk for inflammatory disease and stress-related psychiatric disorders. Not only does this lack of exposure negatively impact our physical health, but it has also been shown to have repercussions for our mental health.
Another recent study found that “children raised in a rural environment, surrounded by animals and bacteria-laden dust, grow up to have more stress-resilient immune systems and might be at lower risk of mental illness than pet-free city dwellers.” Similar research confirms that early exposure to both pets and farm animals is able to reduce the risk of childhood asthma and other inflammatory disorders.
Lowry goes on to say that “this is just one strain of one species of one type of bacterium that is found in the soil but there are millions of other strains in soils…We are just beginning to see the tip of the iceberg in terms of identifying the mechanisms through which they have evolved to keep us healthy. It should inspire awe in all of us.”
While not everyone will be ready and willing to practice geophagy by adding a side of kaolin clay to their dinner, increasing our exposure to the incredible diversity of microbial life of the soil an important element of healthy and holistic livelihoods.