Current Issues

2021 : Volume 1, Issue 1

Craving Edible Clays: Anemia or Androgens

Author(s) : Odimegwu JI 1 , Jane-Sharon EE 1 , Nkemehule FE 1 , Okunnuga J 1 , Buhari AO 1 , Okwuegbuna SN 1 and Duru Chidinma R 2

1 Department of Pharmacognosy , University of Lagos , Nigeria

2 Department of Pharmacognosy , University of Nigeria Teaching Hospital Enugu , Nigeria

Glob J Chem Sci

Article Type : Research Article



Background: The edible raw clay is common in Nigeria and other African countries, occurring mostly like white and grey clays and used frequently in traditional medicine as anti-diarrheic and skin smoother. Some pregnant women swear by it as a solution to morning sickness typified by nausea and general malaise. There has been a noticeable increase in its consumption in recent times which for some individuals is a craving and notably so among pregnant women who most probably acquired the habit from their mothers. There is definitely, a dearth of information on its chemical constituents and therefore possible deleterious effects on the human system, to that end, this study was aimed at ascertaining the cause of the craving for the clays and acquire knowledge about its constituents, to check its health safety to consumers.
Methodology: Ethno-survey of edible raw clay consumption in Nigeria was carried out with more than 850 respondents from Lagos State, a cosmopolitan city of about 16 million people using a semi structured questionnaire. Mineralogical characterization using Proximate analysis, FTIR analysis, Atomic Absorption Spectroscopy, Acute toxicity studies, GC/MS analysis, Phytochemical assays and Hematological analysis on collected clays were used for evaluating the chemical constituents and effects on the living system.
Results: The survey results confirmed that the consumers are aware of possible side effects of raw clay consumption, the chemical analyses showed presence of metalloids like arsenic and silicon and heavy metals e.g. Mercury and Cadmium in the tested clays but they were in minute insignificant amounts. Phytochemical assays showed presence of anthraquinone, but not glycosides, alkaloids, saponins etc. GC analysis surprisingly showed presence of small quantities of androgens and steroids; dihydrocortisone and its metabolites in both the white and grey clays. No anemia was recorded after 28 days of animal studies. The acute toxicity test showed that it is not toxic as no deaths were recorded at 5000mg/kg dosage after 72 hours. The edible clays are not toxic to consumers but care should be taken because of possible adverse health effects from over-consumption and accumulation of contaminants.


Atomic Absorption Spectroscopy; Androgens, Traditional Medicine; Gas Chromatography/Mass Spectrometry and Edible raw clay.


The edible raw clay is properly named “kaolin” which is derived from the word Kau-Ling, or high ridge, the name given to a hill near Jau-Chau Fu, China, where clay was first mined by Sepulveda, et al. [1]. Clay occurs as a mixture of different minerals and commonly contains 10-95% of the mineral kaolinite and traces of other minerals like mica, pyrophyllite talc etc, all in different colours depending on its geological formation and composition Mudi et al. [2] white or grey ones are consumed in Nigeria (Figures 1A and 1B). It is used in traditional medicine as anti-diarrhoeal and for smoothening the skin Bukola, et al. [3-8]. In this report, we use clay and kaolin interchangeably to mean the same thing.

Figure 1: A; White clay B; Grey clay.

The study area; Lagos, is the largest city in the Nigerian state of the same name as well as in Nigeria and Sub-Saharan Africa. It is one of the fastest-growing cities in the world [9-12] and one of the most populous urban areas. It is inhabited by people from diverse ethnic groups; Igbos, Yoruba's and Hausas.

Kaolin is distinguished from other industrial clays based on its fine particle size and pure coloring [3]. It is consumed by many people in the African continent and particularly in Nigeria [6]the behavior/habit of eating soil is known as geophagia and usually classified as pica. Pica is the craving and purposive consumption of substances not culturally defined as food [3]. It is also defined as a psychological eating disorder shown by continuous  consumption of largely non-nutritive substances, such as ice (pagophagia); hair (trichophagia); paper (xylophagic) or soil, (geophagia[4,13].

Geophagia is global though most common with people of African descent [14 ,15] whether living at home in Africa or abroad and can have serious negative effects on the health [6]. The consumption has been linked to the low educational background but the opposite is true for Nigeria where most of the sampling was carried out though some respondents lived abroad. Geophagia cuts across social strata and age, men and women purchase the clays from markets (Figure 2) or supermarkets and consume them , educated people and not so educated also do this. It seems to be a habit gets passed down from parents to offspring's or from friends to friends so it has a very social dimension.