What is the big reason for clay craving ?

Consuming Clay

The ingestion of dirt (geophagy) has been described for diverse species from parrots  to primates  and is particularly prevalent among ungulates. However, little attention has been paid to the significance of this behavior in humans. The preparation of tortillas in many parts of Central America involves soaking them in lime.

Similarly, the Quechua Indians from the high Peruvian Andes supplement their diet by eating a powdered rock porridge (cal), and chewing ashed stalks (llipta) along with coca. These culinary procedures may help alleviate calcium deficiency, but thay are probably not the only purpose. Soaking tortillas increases their calcium content but also makes dough that is more easily rolled out. The Quechua may chew lime because it increases the availability of active alkaloids from coca. A more convincing argument for clay consumption as a behavioral response to calcium deficiency has been made based on pregnant women from many African (and some African-American  societies. Pregnant women report they have a “strong desire” for clay and indicate that consumption provides them with feelings of well-being. They consume it in small amounts throughout the day rather than as a single meal.

clay craving


Hunter  reported that societies showing geophagy in southern Africa frequently lived in areas with low soil calcium content but chose to consume clays high in calcium, particularly those formed by colonies of termites, which accumulate calcium carbonate. Clay from termite mounds is traded throughout western and southern sub-Saharan Africa in much the same manner as is salt. Indeed, one source suggests that “In East Africa the search for edible earths rich in calcium was frequently a cause of tribal raids and the evidence points to these products being instinctively consumed to make good the lack of lime in the customary diet”.

An elegant survey of the relationship between dairy farming and clay consumption by African societies has been published by Wiley and Katz. They compared 15 societies that farmed cows for milk (“dairying”) with 45 that did not (“nondairying”). there were significant differences between the milk drinkers and nondrinkers in the frequency distribution of clay consumption, with the practice being much more common in nondairying societies than dairying ones.

The simplest interpretation of the inverse relationship between dairying and geophagy is that societies that do not drink milk compensate for the lack of calcium by consuming clay. Of course, it is also possible to consider the advent of dairy farming as a manifestation of human calcium appetite. It is unfortunate that calcium intakes of most of the African societies surveyed have not been measured. Values for some of them range from 200 to 2030 mg/d calcium. However, the utility of intake measurements is questionable because such figures do not account for the differences in availability of calcium from different sources. The plant diets of nondairying societies are high in fiber, phytates, and oxalates, which all reduce calcium absorption. They thus increase the effective difference between dairying and non-dairying societies. Another problem is that not all the clay consumed is high in calcium. However, even calcium-free clays are beneficial because clay slows gastrointestinal transit and probably binds to, and thus effectively deactivates, phytates and oxalates. This allows more complete absorption of calcium from other components of the diet.

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