Geophagia in response to stress and arthritis

Pica caused by emetic drugs in laboratory rats with kaolin, gypsum, and lime as test substances

Pica refers to eating nonfood substances. The pica behavior has been the focus of attention in physiological and pharmacological studies, because its consumption is a good marker of nausea in laboratory rats, which cannot vomit due to neuroanatomical reasons. Almost all pica studies with rats have used kaolin clay pellets as nonfood substances. The present study primarily aimed to explore an alternative (or more suitable) substance to kaolin for detection of nausea induced by emetic drugs. Two calcium compounds, gypsum and lime, were evaluated in this study. An injection of lithium chloride (LiCl) increased pica behavior not only in the rats given kaolin but also in the rats given gypsum, suggesting that gypsum consumption could be used as an indicator of nausea. However, its sensitivity was no greater than that of kaolin consumption. In addition, lime is not a useful marker for nausea because the size of pica was small in the LiCl-injected rats, and did not differ from the control in the cisplatin-injected rats. In short, the superiority of kaolin as a test substance for nausea could not be overturned. However, the fact that nauseous rats displayed pica behavior with gypsum and lime refutes the claim that aluminosilicate, the main component of kaolin, is the critical determinant of emetic-caused pica in laboratory rats.

Landscape REE anomalies and the cause of geophagy in wild animals at kudurs (mineral salt licks) in the Sikhote-Alin (Primorsky Krai, Russia)

To test the "rare earth" hypothesis of geophagy, geological and hydrogeochemical studies unparalleled anywhere in the world were carried out at kudurs (salt licks) in two districts in the Primorsky Krai, Russia. The mineral and chemical compositions of geophagic earth consumed by animals, the chemical composition of surface waters and vegetation, and the chemical composition of biological tissues of red deer (Cervus elaphus) were studied in this research. It was found that ultra-fresh surface and fontinal waters in the studied areas contain anomalously high concentrations of rare earth elements (REE), the sums of which exceeded the average values in the Primorsky Krai and worldwide by tenfold, and more. The presence of landscape REE anomalies is confirmed by elevated concentrations of these elements in vegetation. Using electron microscopy, it was determined that the sources of REE in landscape components are rocks containing secondary, readily soluble, REE minerals (hydrophosphates and fluorocarbonates). The study of the chemical composition of animal tissues showed the presence of significant concentrations of heavy REE (HREE) in the blood and brain, which indirectly indicates a high probability of animals developing stress reactions against the background REE-elementosis. Eaten earthy substances in both areas are represented by mixtures of smectite clays and zeolites with high ion-exchange properties. In the digestive tract of animals, such sorbents actively interact with the biological electrolyte, saturating it with sodium ions and absorbing HREE. The main meaning of geophagy is regulation of the concentration and proportion of REE in the body. Sometimes it manifests itself in intake of significant amounts of Na.

Pica in Pediatric Sickle Cell Disease

Pica is the developmentally inappropriate consumption of non-nutritive items for at least one month. Pica can lead to many adverse outcomes, but the exact pathophysiology of pica is unknown or variable across populations. Several studies have evidenced that there is a high prevalence of pica among youth with sickle cell disease (SCD). However, the lack of knowledge regarding the correlates of pica contributes to overlooking the condition, inaccurate diagnoses, and a lack of evidence-based treatments once pica is identified. This review examines the literature to develop a biopsychosocial model of pica in SCD. Elucidating the potential relationships among the proposed biological, psychological, and social factors, and pica will inform our understanding of this phenomenon in pediatric SCD and may guide future research and clinical recommendations.

Endocannabinoid Mechanisms Influencing Nausea

One of the first recognized medical uses of Δ(9)-tetrahydrocannabinol was treatment of chemotherapy-induced nausea and vomiting. Although vomiting is well controlled with the currently available non-cannabinoid antiemetics, nausea continues to be a distressing side effect of chemotherapy and other disorders. Indeed, when nausea becomes conditionally elicited by the cues associated with chemotherapy treatment, known as anticipatory nausea (AN), currently available antiemetics are largely ineffective. Considerable evidence demonstrates that the endocannabinoid system regulates nausea in humans and other animals. In this review, we describe recent evidence suggesting that cannabinoids and manipulations that enhance the functioning of the natural endocannabinoid system are promising treatments for both acute nausea and AN.

Regulation of nausea and vomiting by cannabinoids and the endocannabinoid system

Nausea and vomiting (emesis) are important elements in defensive or protective responses that animals use to avoid ingestion or digestion of potentially harmful substances. However, these neurally-mediated responses are at times manifested as symptoms of disease and they are frequently observed as side-effects of a variety of medications, notably those used to treat cancer. Cannabis has long been known to limit or prevent nausea and vomiting from a variety of causes. This has led to extensive investigations that have revealed an important role for cannabinoids and their receptors in the regulation of nausea and emesis. With the discovery of the endocannabinoid system, novel ways to regulate both nausea and vomiting have been discovered that involve the production of endogenous cannabinoids acting centrally. Here we review recent progress in understanding the regulation of nausea and vomiting by cannabinoids and the endocannabinoid system, and we discuss the potential to utilize the endocannabinoid system in the treatment of these frequently debilitating conditions.

Geophagy in animals and geology of kudurs (mineral licks): a review of Russian publications

This paper reviews from the geological and biological perspectives the achievements of Russian researchers in the field of geophagy, which have not been published in English. It is focused on publications in Russian language about (1) animal behavior related to geophagy, (2) mineral and chemical composition as well as geological characteristics and biological effects of the earths, eaten by animals in various locations in Russia and neighboring countries. The authors argue that the Russian term "solonetz" (salt lick) is too limiting, as animals consume not just salt but many other minerals too. The more general term "kudur" is used for places where animals eat earths. The geological nature and biological properties of kudurites (the common name given to biologically active mineral-crystal substances consumed by animals) and gastroliths (stones consumed by birds and reptiles) are addressed. On the basis of the reviewed data, the authors propose their own views regarding the causes of geophagy.

Why on earth?: Evaluating hypotheses about the physiological functions of human geophagy

Geophagy has been hypothesized to be an adaptive behavior, either as a means to allay nutrient deficiency or to protect against ingested pathogens and toxins. Others have proposed that geophagy is non-adaptive, occurring either to allay hunger or as an epiphenomenon of nutrient deficiencies. This paper evaluates these hypotheses using 482 published cultural-level accounts of human geophagy and 330 accounts of geophagy among 297 species of mammals, birds, and reptiles. Information was extracted from reports of human geophagy to permit statistical analysis; reports of non-human geophagy were tabulated. Human geophagy did not parallel changes in nutrient requirements, occurred most frequently among children and pregnant women and in tropical areas (where pathogen densities are highest), and was associated with ingestion of toxic substances and gastrointestinal distress. Earth ingested by humans was craved and carefully selected and prepared; it had high clay content, but few bioavailable mineral nutrients. In primates, geophagy was associated with both protection from toxins and obtaining nutrients, whereas in other vertebrates it was associated mainly with obtaining nutrients. Our results indicate that human geophagy is best explained as providing protection from dietary chemicals, parasites, and pathogens, whereas animal geophagy may involve both micronutrient acquisition and protection.

Geophagy and potential contaminant exposure for terrestrial vertebrates

Geophagy, the ingestion of earth or earthlike substances, is a behavior that occurs in a wide range of vertebrate groups. Geophagy can be intentional: to acquire necessary nutrients from soil such as sodium or calcium or to acquire a stomach balm for parasites or toxins. It can also be incidental: acquired while foraging or grooming or from prey that have ingested soil. With the spreading effects of human "development," soils contaminated by anthropogenic products will be more frequently encountered by wildlife. Direct ingestion of such soils may be detrimental to the health of animals. In some cases information on the fraction of ingesta that is soil will enable adequate inferences about exposure and techniques are described to determine that fraction. In other cases, inferences about exposure require information on the daily rate of soil ingestion. The daily rate of soil ingestion can be estimated using the fraction of ingesta that is soil and the projections for food requirements. Also described here are methods to project mean daily food requirements and the mean daily rate of soil ingestion. Contaminant exposure by geophagy is affected by filtration of soil fractions, binding of some elements into compounds not absorbable through the gut wall, and neutralizing of toxicity after absorption. Bioavailability of contaminants in soil may also be related to taxon. Geophagy as an important mechanism of toxic exposure has been clearly demonstrated in several studies.

Clay pica has no hematologic or metabolic correlate in chronic hemodialysis patients

OBJECTIVE

Clay pica is a form of compulsive ingestion of non-nutritive substances frequently practiced by dialysis patients. Its consequences are unknown. In this study, we evaluated the effect of regular consumption of clay on hematologic and metabolic profiles in hemodialysis patients.

DESIGN

A prospective, case-control study with use of structured questionnaire.

SETTING

Free-standing hemodialysis units.

PATIENTS

One hundred thirty-eight patients on hemodialysis for at least 12 months were interviewed. Thirteen of 138 (9.4%) confessed to clay pica. Ten randomly selected patients with no history of pica served as control.

INTERVENTION

Average of all laboratory profiles and interdialytic weight gain (IDWG) over a 3-month period were recorded. Assay of the aluminum (Al), silica (Si), and iron (Fe) content of commercially purchased clay was performed.

MAIN OUTCOME MEASURE

Comparison of laboratory profiles and IDWG between cases and control. Estimation of the daily consumption of Al, Fe, and Si from clay and their relationship to the laboratory profiles.

RESULTS

There was no statistically significant difference in the levels of Al, albumin, calcium, ferritin, hematocrit, iron saturation, phosphorus, and IDWG between pica cases and control. Iron was significantly higher in pica patients (13.0 +/- 7.9 micromol/L v 7.5 +/- 2.5 micromol/L, P =.04), but potassium was higher among control than pica cases (4.9 +/- 0.7 mmol/L v 4.4 +/- 0.6 mmol/L, P =.07). Estimated metal exposure from daily clay consumption per patient were: Al (1-2 mg), Fe (11-23.5 mg), and Si (2-4.5 g). Multivariate logistic regression analysis failed to show any association between clay consumption and nutrition, anemia, or mineral metabolism (R(2) = 0.0, P =.79).

CONCLUSION

Clay pica does not appear to be detrimental to the hematologic and metabolic milieu of hemodialysis patients. The practice should, however, be discouraged, because of potential for ingestion of unknown substances, and reported potential for gastrointestinal complications.