Geophagy

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The red-and-green macaw eats clay from exposed riverbanks, allowing them to utilize nutrients in harmful foods.

Geophagy is the practice of eating earthy or soil-like substances such as clay, and chalk, in order to obtain essential nutrients such as sulfur and phosphorus from the soil. It is closely related to pica, a classified eating disorder in the DSM-IV characterized by abnormal cravings for nonfood items^[1].

The many possible health benefits of geophagy remain under study and are much debated. Many scientists believe that it is only harmful, while others argue that there may be adaptive benefits to the practice, since humans and other animals alike have engaged in it for thousands of years.

[edit] Classification and diagnosis

The International Classification of Diseases includes geophagia among eating disorders (F50) as a variety of pica, the ingestion of non-foods. However, dirt can constitute a source of iron, although the bioavailability of such mineral has not been ascertained. For example, red clays often have iron in ferrous form, poorly absorbed by humans.

It is also associated with iron deficiency.

Geophagia can be diagnosed, in absence of other evidence, by measuring the concentration of silica in feces.

[edit] Possible health benefits

Bentonite clay is available worldwide as a digestive aid; kaolin and diosmectite are also widely used digestive aids and as the base for some medicines. Attapulgite, a substance found in clay in the Southern United States, is an active ingredient in many anti-diarrheal medicines.^[2]

In a Science Digest article (Paraquat: a Potent Weed Killer is Killing People^[3]), it is recommended that a paraquat poisoning victim promptly swallow dirt, even at the risk of salmonella, because paraquat is deactivated upon contact with soil. Otherwise, a sufficiently lethal dose would cause damage to the liver, kidneys, and especially the lungs, usually causing death by asphyxiation by causing severe fibrosis. Lung transplants in two victims merely delayed their deaths because chemical levels still in their bodies subsequently damaged the transplanted lungs, too.

There is also evidence that supports the usefulness of the flora found in soil. Some have even suggested that it is useful, if not vital, in the establishment of healthy bacteria within the digestive tract, addressing the problems presented by Crohn's Disease and Leaky Gut Syndrome. Highly adsorbent families of clays have been demonstrated to cause the lining of the vertebrate gut to change both on a cellular and acellular level, potentially protecting the gut from chemical insults as well as alleviating ailments such as esophagitis, gastritis, and colitis.

[edit] Possible health risks

Like coprophagia, it may be dangerous because parasite eggs can be passed in animal feces. Baylisascaris eggs, for instance, are dropped millions at a time by raccoons and other wildlife. They can stay dormant for years, remaining viable even in extreme temperatures and drought. Some of these roundworm eggs may remain in the soil long after the feces have decomposed, and become active in the digestive tract upon being consumed. Children's predilection to engage in geophagia makes them more susceptible to worm infestations. Other dangers associated with geophagia include damage to tooth enamel, the ingestion of a variety of bacteria, lead poisoning and intestinal obstruction.

[edit] In rural and indigenous cultures

Geophagy is most often seen in rural or preindustrial societies among pregnant women and children. However, it is practiced by members of all races, social classes, ages, and sexes. In other parts of the world the practice is less stigmatized, and geophagy is not studied as a pathology but rather as an "adaptive behavior" that supplements the diet with essential nutrients or treats a disorder such as diarrhea.^[4]

In some parts of the world, geophagia is a culturally sanctioned practice. In many parts of the developing world, earth intended for consumption is available for purchase. Rising food prices in Haiti have driven many of the nation's poor to consume clay cookies on a regular basis, to ward off hunger. The cookies are made of clay, salt, water and vegetable shortening or margarine.^[5][6]

In parts of Africa, rural United States, and villages in India clay consumption may be correlated with pregnancy as women eat clay to eliminate nausea, possibly because the clay coats the gastrointestinal tract and absorbs dangerous toxins. The clay may also provide critical calcium for fetal development (Vemeer).

Cooked, baked, and processed dirt and clay are still sold in health food stores and rural flea markets in the Southern United States, although this practice is less common than it once was.

Geophagy was also practiced by Native Americans in California and Peru who would eat earth with acorns and potatoes to neutralize potentially harmful alkaloids. Clay was used in the production of acorn bread in California and Sardinia, Italy.

In the United States in the 1800s, geophagy was common among slaves, who were nick-named "clay-eaters" because they had been known to consume clay, as well as spices, ash, shalk, grass, plaster, paint, and starch.^[7] Geophagy was at that time sometimes referred to as "Cachexia Africana", and slaves engaged in it to compensate for their nutritionally deficient diets by eating vitamin-enriched clay and other substances. Many slave owners believed that Cachexia Africana caused illnesses among their slaves and implemented certain devices to restrict their slaves from consuming dirt. In the southern United States one specific device was the mouth lock; a face piece that prevented slaves from consuming anything other than their rationed meals (Donald E. Vermeer and Dennis A. Frate, 414,1975).

[edit] In animals

Geophagy has been observed in birds. Notably, many species of South American parrots have been observed at clay licks, whilst Sulphur-crested Cockatoos have been observed ingesting clays in Papua New Guinea (Discover, 1998) as well as in Glenbrook in Blue Mountains of Australia (Parrots Magazine, 2000). Analysis of most soils consumed by wild birds show that they prefer soils with high clay content, often with the smectite and bentoninte clay families being well represented. In vitro and in vivo tests of these soils indicate that they release biologically important quantities of minerals like calcium and sodium, as well as adsorbing substantial quantities of small charged compounds such as alkaloids. Because the clays release minerals and adsorb other cations as part of the same process of cation exchange, it remains challenging to determine which function is the more important motivator in any given instance of avian geophagy. Separate from soil ingegstion, pet birds are often provided with grit which is retained in their gizzards to aid in grinding the food they eat.

Chimpanzees in Kibale National Park, Uganda have been observed to consume soil rich in kaolinite clay shortly before or after consuming plants including Trichilia rubescens, which possesses antimalarial properties in the laboratory. Simulated mastication and digestion reveals that the clay helps to release active antimalarial components from the leaves. The same type of soil is used by local healers to treat diarrhea,^[8] presumably by the same mechanism as over-the-counter antidiarrheal preparations.

[edit] Cultural taboos against geophagy

The cultural meaning of dirt may be a factor in geophagy being considered an unacceptable practice. Western cultures view dirt as being filthy, especially after Germ Theory arose. Dirt is similar to miasma, in that theory, which is a place where diseases are made and spread. The persistence of geophagy within a family or community can also partially be explained by a simple mother/daughter sharing mechanism. A crucial and sometimes hazardous part of rural communities is the act of giving birth. Without advanced medical knowledge, local customs become key to a healthy outcome. Geophagy enters the picture when daughters would "follow the diet of a woman that they knew had been successful at giving birth".^[9] The maternal chain can therefore act as an important vector in the continuance of this act.

[edit] In popular culture

• In One Hundred Years of Solitude, by Gabriel García Márquez, Rebeca exhibits symptoms of geophagy by secretly and compulsively eating the soil in the yard.
• In the 1937 film adaptation of Pearl S. Buck's The Good Earth, during a prolonged drought, O-Lan (Luise Rainer) serves the children something to eat. Neighbors desperate for food discover that she had fed them the good earth itself, because, as she says, it is warm and gives life.
• In the novel Survivor by author Chuck Palahniuk, (Page 172), one female Creedish cult survivor is said to have killed herself after eating dirt, or committing "Geophagy", until she experienced an esophageal rupture.
• In the movie Raising Arizona, H.I. (Nicholas Cage) shares a prison cell with a man who tells of eating sand when there was nothing else.
• salad fingers, from the cartoon of the same name suffers from geophagy as well as other forms of pica
• Fox News reporter Steve Harrigan took a bite out of a dirt cookie baked by a Haitian woman in a report about food shortages.

[edit] Notes

[edit] References

• Callahan GN. Eating dirt. Emerg Infect Dis [serial online] 2003 Aug . Available from: URL: http://www.cdc.gov/ncidod/EID/vol9no8/03-0033.htm
• Dominy N, Davoust E, Minekus M (2004): Adaptive function of soil consumption: an in vitro study modeling the human stomach and small intestine. J Experimental Biology 207, 319-324 [1]
• Donald E. Vermeer and Dennis A. Frate. "Annals of the Association of American geographers." Vol.65 No.3, 1975. 414-416
• Hamilton G (1998): Let them eat dirt. New Scientist 159(2143):26-31
• Harvey P, Dexter P and I Darnton-Hill (2000): The impact of consuming iron from non-food sources on iron status in developing countries. Public Health Nutrition 3(4):375-383
• Kwong, Alica M.; Henry, Jaques. "Why is geophagy treated like dirt?" Deviant Behavior: An Interdisciplanary Journal.
• Lagercrantz, Sture. "Geophagical Customs in Africa and among the Negroes in America." Studia Ethnographica Upsaliensia 17 (1958): 24–81.
• Reid R (1992): Cultural and medical perspectives on geophagia. Med Anthropol 13(4):337-51
• Root-Bernstein,Michele : Honey, Mud, Maggots and Other Medical Marvels, Houghton Mifflin, (1997).
• Vemeer, Donald. 1971. "Geophagy Among the Ewe of Ghana." Ethnology 10:56-72.
• Vermeer D (1966): Geophagy among the Tiv of Nigeria. Ann Assoc Am Geographers 56(2):197
• Walker A, Walker B (1997): Pica. J Soc Health 117(5):280-4
• Wiley, Andrea S. "Geophagy." Encyclopedia of Food and Culture. Ed. Solomon H. Katz. Vol. 2. New York: Charles Scribner's Sons, 2003. 120-121.
• Wiley, Andrea S., and Solomon H. Katz. "Geophagy in Pregnancy: A Test of a Hypothesis." Current Anthropology 39, no. 4 (1998): 532–545.
• Wong M, Simeon D (1993): The silica content of faeces as an index of geophagia: its association with age in two Jamaican children's homes. J Trop Pediatr 39(5):318-9
• Ziegler J (1997): Geophagia: a vestige of paleonutrition. Trop Med Int Health 2(7):609-11

[edit] External links

• Dirt as Food
• Eating Dirt
• Diamond on Geophagy
• CDC on eating dirt
• Health A to Z - Pica
• Haitians Resort to Dirt Eating