Geophagy, iron status and anaemia among pregnant women on the coast of Kenya

In a cross sectional survey based in an antenatal clinic at Kilifi District Hospital, Coast Province, Kenya, 154 of 275 pregnant women (56%) reported eating soil regularly. Geophagous women had lower haemoglobin and serum ferritin concentrations than non-geophagous women (mean haemoglobin level 9.1 vs. 10.0 g/dL, P<0.001; median ferritin level 4.5 vs. 9.0 mu g/L, P<0.001). In multiple linear regression analyses, geophagy was a significant predictor of haemoglobin (beta=-6.4, P=0.01) and serum ferritin concentrations (beta=-6.6, P=0.002), while controlling for gestational age and malaria and hookworm infection. Another 38 pregnant women, who reported eating soil regularly, participated in focus group discussions and were interviewed on geophagy. The most commonly eaten soil was from the walls of houses. The median estimated daily intake was 41.5 g (range 2.5-219.0 g). Twenty-seven of these women assisted in the collection of soil samples which were then analysed for their content of iron, zinc and aluminium after extraction with 0.1 M HCl. The average daily soil intake supplied the geophagous women with 4.3 mg of iron, corresponding to 14% of the recommended dietary allowance of iron for pregnant women. The study revealed a strong negative association between geophagy and both haemoglobin and ferritin status. At the same time it demonstrated the potential of soil as a source of dietary iron for geophagous women. These seemingly contradictory results might be due to other components in the soil interfering with iron uptake or metabolism. Alternatively, it may be that the geophagous women had extremely depleted iron stores before starting to ear soil. From these cross-sectional data, no inference about causality could be made.