Toward a Comprehensive Approach to the Collection and Analysis of Pica Substances, with Emphasis on Geophagic Materials

Pica, the craving and subsequent consumption of non-food substances such as earth, charcoal, and raw starch, has been an enigma for more than 2000 years. Currently, there are little available data for testing major hypotheses about pica because of methodological limitations and lack of attention to the problem.In this paper we critically review procedures and guidelines for interviews and sample collection that are appropriate for a wide variety of pica substances. In addition, we outline methodologies for the physical, mineralogical, and chemical characterization of these substances, with particular focus on geophagic soils and clays. Many of these methods are standard procedures in anthropological, soil, or nutritional sciences, but have rarely or never been applied to the study of pica.Physical properties of geophagic materials including color, particle size distribution, consistency and dispersion/flocculation (coagulation) should be assessed by appropriate methods. Quantitative mineralogical analyses by X-ray diffraction should be made on bulk material as well as on separated clay fractions, and the various clay minerals should be characterized by a variety of supplementary tests. Concentrations of minerals should be determined using X-ray fluorescence for non-food substances and inductively coupled plasma-atomic emission spectroscopy for food-like substances. pH, salt content, cation exchange capacity, organic carbon content and labile forms of iron oxide should also be determined. Finally, analyses relating to biological interactions are recommended, including determination of the bioavailability of nutrients and other bioactive components from pica substances, as well as their detoxification capacities and parasitological profiles.This is the first review of appropriate methodologies for the study of human pica. The comprehensive and multi-disciplinary approach to the collection and analysis of pica substances detailed here is a necessary preliminary step to understanding the nutritional enigma of non-food consumption

The association between urinary sodium excretion and blood pressure in children.

This study explored the association between sodium excretion and blood pressure (BP). A new method was used to minimize the measurement error introduced by the large intrinsic variability of 24-hour sodium excretion. The ratio of intra- to interindividual variation was used to estimate the number of measurements needed to characterize the individual. When seven consecutive 24-hour samples were collected from 73 children, ages 11-14 years, a significant correlation between mean individual sodium excretion and BP was demonstrated. The independent relationship persisted when controlling for height, weight, pulse, age, sex and race (p = 0.045), but was eliminated by simultaneously considering mean creatine excretion. Although the cross-sectional association described is quantitatively weak, a linear relationship between BP and sodium over the range consumed in this society could be important for prevention