Nutritive potential of some ‘edible’ soils in Blantyre city, Malawi

Background Pregnant women in Malawi consume soil, but the nutritive potential of these soils is uncertain.
Methods We collected ‘edible’ Malawian soil samples from Ndirande, Mpingwe and Soche hills and bought an Indian soil sample from a shop in Limbe and tested them for iron, calcium, zinc, magnesium, lead, pH, Bacillus and Clostridium, using standard methods of analyses.
Findings Based on an average daily consumption of fifty grammes of soil, Blantyre ‘edible’ soils can supply 0.006%, 0.2%, 7% and 74% whilst the Indian soil may supply 0.008%, 0.27%, 8.7%, and 65% of the WHO recommended minimum daily intakes of Magnesium, Calcium, Zinc and iron, respectively. However, both the Blantyre and Indian ‘edible’ soils also have some traces of lead (0.05 to 0.07 mg/g soil) and spores of Bacillus (4900 – 13475 colonies/gram) and Clostridium (5050 – 9050 colonies/gram), which may have undesirable health effects. Blantyre soils were similar but significantly different from the Indian soil which had higher calcium, magnesium, zinc and lead but lower iron.
Conclusion The soils have nutritive potential, but they also have harmful aspects.
Recommendation Further multidisciplinary research should be conducted to assess the nutritive potential of soils from other areas in Malawi and to examine the health effects of lead and bacterial spores.