Dietary mineral supplies in Malawi: spatial and socioeconomic assessment

Edward J M Joy,Martin R Broadley,Diriba B Kumssa,E Louise Ander,Michael J Watts,Scott D Young,Allan D C Chilimba

doi:10.1186/s40795-015-0036-4

Edward J M Joy, Martin R Broadley + Show 5 more

Open Access

https://doi.org/10.1186/s40795-015-0036-4

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Abstract

Dietary mineral deficiencies are widespread globally causing a large disease burden. However, estimates of deficiency prevalence are often only available at national scales or for small population sub-groups with limited relevance for policy makers. This study combines food supply data from the Third Integrated Household Survey of Malawi with locally-generated food crop composition data to derive estimates of dietary mineral supplies and prevalence of inadequate intakes in Malawi. We estimate that >50 % of households in Malawi are at risk of energy, calcium (Ca), selenium (Se) and/or zinc (Zn) deficiencies due to inadequate dietary supplies, but supplies of iron (Fe), copper (Cu) and magnesium (Mg) are adequate for >80 % of households. Adequacy of iodine (I) is contingent on the use of iodised salt with 80 % of rural households living on low-pH soils had inadequate dietary Se supplies compared to 55 % on calcareous soils; concurrent inadequate supplies of Ca, Se and Zn were observed in >80 % of the poorest rural households living in areas with non-calcareous soils. Prevalence of inadequate dietary supplies was greater in rural than urban households for all nutrients except Fe. Interventions to address dietary mineral deficiencies were assessed. For example, an agronomic biofortification strategy could reduce the prevalence of inadequate dietary Se supplies from 82 to 14 % of households living in areas with low-pH soils, including from 95 to 21 % for the poorest subset of those households. If currently-used fertiliser alone were enriched with Se then the prevalence of inadequate supplies would fall from 82 to 57 % with a cost per alleviated case of dietary Se deficiency of ~ US$ 0.36 year−1. Household surveys can provide useful insights into the prevalence and underlying causes of dietary mineral deficiencies, allowing disaggregation by spatial and socioeconomic criteria. Furthermore, impacts of potential interventions can be modelled.

Highlights

Dietary mineral deficiencies are widespread globally causing a large disease burden
Food consumption Household food consumption and socioeconomic data were derived from the Third Malawi Integrated Household Survey (IHS3) in which a nationally-representative sample of 12,271 households were interviewed during March 2010-March 2011 [28]
The number of interviewed households varied between expenditure quintiles, the number of individuals covered in each expenditure quintile was equivalent

Summary

Introduction

Dietary mineral deficiencies are widespread globally causing a large disease burden. estimates of deficiency prevalence are often only available at national scales or for small population sub-groups with limited relevance for policy makers. Hidden hunger is widespread globally with an estimated two billion people at risk of vitamin A, iron (Fe), iodine (I) and zinc (Zn) deficiencies, causing a considerable social and economic burden in low-income countries including sub-Saharan Africa [2,3,4,5,6,7,8,9,10]. Health outcomes can be a useful proxy to measure prevalence of dietary nutrient deficiencies, for example stunting as an indicator of Zn deficiency [16]. Such relationships can be confounded by environmental factors or multiple causes of the same health outcome and surveys of health outcomes remain expensive and logistically challenging to conduct. Phytic acid (PA) is the principal form of phosphorus in cereal grains and inhibits the absorption of Fe, Mg and Zn in the human gut [17]

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