SEGH Articles

Mapping Hidden Hunger in Malawi

14 February 2016
Maps for Malawi predict spatial variation in the dietary supply of seven essential elements (calcium, copper, iodine, iron, magnesium, selenium and zinc).

Edward Joy and Louise Ander describe how recently created maps of Malawi predict spatial variation in the dietary supply of seven essential elements (calcium, copper, iodine, iron, magnesium, selenium and zinc). These maps combine information on soil and crop properties, household dietary choices and socio-economic factors. This information can help to identify key controls on mineral micronutrient dietary deficiencies – also known as “hidden hunger” – and identify research priorities for the development of appropriate and feasible interventions to reduce population-wide hidden hunger.


Life in Malawi

Malawi is a land-locked country in south-east Africa. The majority of households rely on subsistence farming with typical land size ~2 ha. Average Gross National Income is just USD 308 capita-1 compared to USD 42,098 capita‑1 in the UK. In this context, the quality of diets is affected by the ability of households to grow sufficient, nutritious food, and to supplement this with purchases. Typically, households devote most of their land to the staple crop maize which is a rational strategy when the primary objective is to satisfy energy requirements. If land and other resources such as labour permit, households may also grow legumes, vegetables, fruits etc. and some grow tobacco as a cash crop.

Hunger, or fear of hunger, is a common concern for most Malawian households. Yet hidden hunger, meaning inadequate vitamin or mineral intakes, is even more widespread. For example, zinc deficiency contributes to a very high stunting rate of 48% of children in rural areas. Food insecurity is one reason why life expectancy at birth is ~55 years, similar to that in the UK 100 years ago. Better data and an improved understanding of diets and nutrition is important to inform health and agriculture policies. We matched food consumption data recorded in a recent national household survey with crop composition data refined by soil type to quantify and map dietary mineral supplies and deficiencies across Malawi.


Not only “hidden” hunger…..

Most smallholder farmers rely on manual labour and hence have active lifestyles. As part of this study, we show that energy supplies are likely to be inadequate to support active lifestyles in >50% of households. This observation is supported by the finding that as incomes increase, there is no proportional decrease in spending on food. This suggests that those lowest income households are short of essential food.


Seasonal intakes of vegetables cause fluctuation of dietary mineral supply….

Most of Malawi has one long growing (rainy) season from December to April. Subsistence farming results in a change in availability and consumption of pulses, fruits and vegetables (including the leaves of edible ‘weeds’), which are consumed more frequently at the end of the rainy season. This leads to seasonal variation in the dietary supply of essential trace elements.


River and lake fish improve dietary micronutrient supply…..

The most commonly-consumed animal product is fish, mainly sourced from Lake Malawi and Lake Chilwa. Fish consumption is greater in households close to the major lakes and this leads to greater consumption of several micronutrients, particularly calcium, selenium and zinc.

Wealthier households have healthier diets, but soil type has the greatest control over selenium supplies…..

Household wealth was negatively associated with risk of deficiency for all nutrients studied. This is due to greater consumption of foods including micronutrient-rich animal-source foods. Previous research has shown that calcareous soils in Malawi result in higher crop selenium concentrations. Here we show that the effect of soil type is more important than household wealth in providing beneficial increases in dietary selenium supply.

 

What next?

Ensuring food security in Malawi remains a huge challenge but there are possible interventions to improve dietary mineral supplies. Interventions can be successful, e.g. the national salt iodisation programme which is responsible for the majority of the dietary supply of iodine in Malawi (as with many other countries globally). There are crop breeding programmes to increase micronutrient concentrations, particularly for zinc. Selenium could be increased in crops through enriched fertilisers, as shown in experimental trials in Malawi conducted on soils with low inherent selenium availability. Fertiliser fortification is being successfully used as a national approach to increasing dietary selenium supply in Finland.

Further information

You can read our open access paper if you would like find out more, including the full set of maps we have generated for Malawi.

This work was one of the outputs of Edward’s PhD, as well as that of the ongoing PhD project of Diriba Kumssa. Dr Edward Joy was supervised by Prof. Martin Broadley, Dr Scott Young, the late Prof. Colin Black (School of Biosciences, University of Nottingham (UoN)), Dr Louise Ander, Dr Michael Watts (British Geological Survey (BGS)) and Dr Allan Chilimba (Ministry of Agriculture and Irrigation, Malawi), with PhD funding from UoN and BGS.

Edward’s PhD research is part of an ongoing programme of research in the Centre for Environmental Geochemistry (School of Biosciences, UoN and Inorganic Geochemistry, BGS) alongside our fantastic wider network of research partners in Malawi, and beyond.

Our most recent activity is the initiation of the Royal Society – Department for International Development (RS-DFID) Africa Capacity Building project “Strengthening African capacity in soil geochemistry” in Malawi, Zambia and Zimbabwe. We have recently welcomed 5 new PhD students into this 5 year project, two of whom will directly build upon outputs from Edward’s PhD, with plans for more! Edward is now working at the London School of Hygiene Tropical Medicine (LSHTM).

by Edward Joy and Louise Ander

 

 

Keep up to date

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Agro-ecological suitability assessment of Chinese Medicinal Yam under future climate change 2019-10-15

    Abstract

    Chinese Medicinal Yam (CMY) has been prescribed as medicinal food for thousand years in China by Traditional Chinese Medicine (TCM) practitioners. Its medical benefits include nourishing the stomach and spleen to improve digestion, replenishing lung and kidney, etc., according to the TCM literature. As living standard rises and public health awareness improves in recent years, the potential medicinal benefits of CMY have attracted increasing attention in China. It has been found that the observed climate change in last several decades, together with the change in economic structure, has driven significant shift in the pattern of the traditional CMY planting areas. To identify suitable planting area for CMY in the near future is critical for ensuring the quality and supply quantity of CMY, guiding the layout of CMY industry, and safeguarding the sustainable development of CMY resources for public health. In this study, we first collect 30-year records of CMY varieties and their corresponding phenology and agro-meteorological observations. We then consolidate these data and use them to enrich and update the eco-physiological parameters of CMY in the agro-ecological zone (AEZ) model. The updated CMY varieties and AEZ model are validated using the historical planting area and production under observed climate conditions. After the successful validation, we use the updated AEZ model to simulate the potential yield of CMY and identify the suitable planting regions under future climate projections in China. This study shows that regions with high ecological similarity to the genuine and core producing areas of CMY mainly distribute in eastern Henan, southeastern Hebei, and western Shandong. The climate suitability of these areas will be improved due to global warming in the next 50 years, and therefore, they will continue to be the most suitable CMY planting regions.

  • Application of stable isotopes and dissolved ions for monitoring landfill leachate contamination 2019-10-15

    Abstract

    We evaluated groundwater contamination by landfill leachate at a municipal landfill and characterized isotopic and hydrogeochemical evidence of the degradation and natural attenuation of buried organic matter at the study site. Dissolved ion content was generally much higher in the leachate than in the surrounding groundwater. The leachate was characterized by highly elevated bicarbonate and ammonium levels and a lack of nitrate and sulfate, indicating generation under anoxic conditions. Leachate δD and δ13CDIC values were much higher than those of the surrounding groundwater; some groundwater samples near the landfill showed a significant contamination by the leachate plume. Hydrochemical characteristics of the groundwater suggest that aquifer geology in the study area plays a key role in controlling the natural attenuation of leachate plumes in this oxygen-limited environment.

  • Lead transfer into the vegetation layer growing naturally in a Pb-contaminated site 2019-10-10

    Abstract

    The lead was one of the main elements in the glazes used to colour ceramic tiles. Due to its presence, ceramic sludge has been a source of environmental pollution since this dangerous waste has been often spread into the soil without any measures of pollution control. These contaminated sites are often located close to industrial sites in the peri-urban areas, thus representing a considerable hazard to the human and ecosystem health. In this study, we investigated the lead transfer into the vegetation layer (Phragmites australis, Salix alba and Sambucus nigra) growing naturally along a Pb-contaminated ditch bank. The analysis showed a different lead accumulation among the species and their plant tissues. Salix trees were not affected by the Pb contamination, possibly because their roots mainly develop below the contaminated deposit. Differently, Sambucus accumulated high concentrations of lead in all plant tissues and fruits, representing a potential source of biomagnification. Phragmites accumulated large amounts of lead in the rhizomes and, considering its homogeneous distribution on the site, was used to map the contamination. Analysing the Pb concentration within plant tissues, we got at the same time information about the spread, the history of the contamination and the relative risks. Finally, we discussed the role of natural recolonizing plants for the soil pollution mitigation and their capacity on decreasing soil erosion and water run-off.