Background
Dietary mineral deficiencies are widespread in Africa. Our previous studies in Malawi revealed population-level shortfalls in dietary calcium and selenium supply but adequate dietary magnesium (Mg) supply. Here we examine dietary Mg supply throughout Africa.
Methods
Food supply data from 1961 to 2007 were compiled using Food and Agriculture Organization (FAO) Food Balance Sheets (FBSs). Magnesium supply was estimated for each country using regional food Mg composition tables.
Results
Mean Mg supply in 2007 was 649 mg capita -1 d-1, ranging from 188 mg d-1 in Eritrea to 1,828 mg d-1 in Burkina Faso. Magnesium supply was greater in West Africa than in other regions, was dominated by sorghum, maize and wheat and was correlated with calorie supply. The World Health Organization (WHO) Estimated Average Requirement (EAR) for Mg (217 mg capita -1 d-1 for adult males) was exceeded in most countries. Using the EAR cut-point method, the risk of dietary Mg deficiency in Africa is <4 % and unlikely to be a major problem, assuming access to sufficient food and that phytic acid does not compromise Mg absorption.
Conclusions
Estimating Mg supply is highly sensitive to concentration data available for the primary staple crops. Given that soil factors profoundly affect crop Mg concentration, there is a need to increase the spatial resolution of food composition tables for the staple crops.