Geophagy

Geophagy is an eating disorder characterized by the regular and excessive consumption of non-nutritive soil, clay, or similar earth materials and represents a more specific form of pica behavior. This behavior is observed across various cultures and age groups worldwide, particularly among children and pregnant women.

Historical and Cultural Aspects

The practice of eating soil dates back to ancient times. Some studies indicate that the earliest evidence of geophagy originates from prehistoric sites near the Kalambo Falls, located between Zambia and Tanzania, and extends as far back as Homo habilis. Ancient Chinese, Egyptians, African communities, and inhabitants of Anatolia have consciously or unconsciously consumed soil for thousands of years.

Historically, certain clays were believed to possess therapeutic properties. For instance, during the Roman Empire, clay tablets mined from the island of Lemnos, known as “Terra Sigillata” (sealed earth), were used and traded for treating ailments such as snakebites and indigestion. In the Ottoman Empire, the trade of these tablets continued under the name “Tin-i Mahtum” and gradually acquired religious and cultural motifs.

In Africa, geophagy is generally regarded as an integral part of cultural tradition and is perceived as a normal behavior; geophagic materials are even sold in markets. In Anatolia, the practice of eating soil also has ancient roots and continues to this day.

Causes

The exact cause of geophagy is not fully understood, but it is associated with several factors:

• Nutritional Deficiencies: Most commonly linked to iron and zinc deficiencies. It remains debated whether iron deficiency leads to geophagy or whether geophagy causes iron deficiency.
• Cultural and Psychological Factors: In some societies, it is part of a traditional practice or belief system. Sensory preferences, such as smell and taste, may also play a role.
• Pregnancy-Related Conditions: Soil consumption may occur during pregnancy to alleviate nausea or as a preventive measure against anemia.
• Hunger and Detoxification: It has been reported that soil is consumed during periods of famine to reduce hunger or to mitigate the harmful effects of certain plants.

Materials Consumed and Geological Properties

The soils consumed in geophagy are typically rich in clay. Research has analyzed the mineralogical and geochemical properties of soil and rock samples consumed in this practice. A study conducted in Central Anatolia determined that soil samples collected from the Niğde and Aksaray regions—used both in the production of pekmez and consumed directly—are of Neogene age and originated from lacustrine environments. These samples consist primarily of altered, easily excavated portions of marl, travertine, tuff, and dolomite.

XRD analyses identified minerals such as clay, mica, carbonate (calcite, dolomite), cristobalite, amphibole, quartz, feldspar, and opal-CT in these soils. Major element analyses revealed dominance of CaO+Al²O³+Fe²O³ in the Bor region, CaO+SiO²+Fe²O³ in the Ulukışla region, and CaO+MgO in the Emirgazi region. Trace element analyses showed elevated levels of Sr, Ba, Ce, Zn, and As in Bor region samples; U, Ce, Ba, Zr, Sr, and Ni in Ulukışla region samples; and Ba, Sr, La, Ce, Co, and Zr in Emirgazi region samples. Notably, uranium (U) concentrations in Ulukışla region samples—particularly those used as pekmez soil—reached up to 46 ppm.

Health Effects

Soil consumption carries both potential benefits and serious health risks:

• Complications: Depending on the quantity and type of material ingested, complications such as anemia, malnutrition, growth retardation, parasitic infections, and poisoning may occur. Clay minerals can inhibit nutrient absorption, leading to mineral imbalances. Heavy metals such as lead, mercury, and cadmium present in soil may impair liver, kidney, and brain development in children. Variations in levels of elements such as radon, thorium, uranium, and arsenic in soil can also cause health problems. Consuming soil raw allows harmful contaminants to enter the body directly.
• Potential Beneficial Effects (Hypotheses): Some researchers suggest that geophagy may help alleviate nausea, bind toxins, or provide nutritional supplementation; however, further research is needed to confirm these hypotheses.

Prevalence and Research

Geophagy is common in many regions of Anatolia, particularly in rural areas, among low-income families, children, and pregnant women. A study conducted in Arguvan district of Malatya found that 39 out of 237 randomly selected individuals had a history of or currently engaged in soil consumption, with the majority being women. The study emphasized that the practice is not uncommon even among educated individuals and is culturally accepted as normal. In a study carried out in the Ihlara Valley, it was found that 71% of people consumed soil due to an inability to resist its smell during rainy weather, while 14.4% consumed it because they enjoyed its taste.

Geophagy is a global and historical phenomenon with complex causes and potential health implications. Medical geology studies aim to clarify the impact of this behavior on human health more clearly.