Human bioaccessibility of Fe, Mn, Zn and Cu from consumed earth materials in Vhembe District, South Africa

ABSTRACT

Earth materials, such as clays, anthills and dried-up pond sediments, are consumed by humans as a means of supplementing essential elements and for protection against toxins. A two-stage physiologically based extraction test (PBET), simulating the human stomach and intestine, was used to estimate the human bioaccessibility of Fe, Mn, Zn and Cu. Extracts from these earth materials were analysed by inductively coupled plasma mass spectroscopy (ICP-MS). Principal component analysis (PCA) was used to evaluate the relationships amongst bioaccessible element concentrations. The mean concentrations of elements for the stomach and intestinal phases were as follows; Fe, 0.94 and 0.20 ppm; Zn, 81.44 and 22.42 ppm; Mn, 10.10 and 1900 ppm; Cu, 24.93 and 230.04 ppm. Iron and Zn showed higher bioaccessibility under gastric conditions whilst Cu was bioaccessible only in the intestinal phase extract. Concentrations of Mn were the same in gastric and intestinal phases. There were strong associations between Zn, Fe and Mn. Some of the consumed earth materials could contribute to the daily recommended nutrient intake of Fe and provide a significant source of Mn and Cu for consumers of earth materials.

Keywords:

• Earth materials
• bioaccessibility
• intestine
• recommended nutrient intake
• stomach

ACKNOWLEDGEMENTS

This study was supported by funds from the Research and Publication Committee, University of Venda, South Africa.