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.