|Edward in his panama hat out in Malawi|
The last couple of years have been a steep learning curve for me: a faulty radiator can write off your engine; laptop battery life is everything; and you may need to hire guards to keep monkeys off your maize trials! These have been valuable lessons as I plan to continue similar research in Ethiopia starting in December. Overall, it has been a pleasure living in Malawi, a country endowed with some very beautiful landscapes and incredibly friendly folk – it’s not uncommon on sampling trips to be invited into farmers’ houses for roast pumpkin and peanuts.
My project aim, using cross disciplinary science, is to improve the accuracy and spatial resolution of dietary mineral supply estimates in Malawi and to investigate the potential of agricultural solutions to mitigate dietary mineral deficiencies. The Malawi Ministries of Agriculture and Health have been very supportive and hopefully the outputs will be useful to them, for example in developing fertiliser policies and targeting nutrition strategies.
So here's a look in more detail at the work I've been doing out in Malawi...
Humans require 22 mineral elements for their wellbeing including calcium (Ca), iron (Fe), magnesium (Mg), selenium (Se) and zinc (Zn). The biological functions of elements include bone structure (Ca and Mg) and, as constituents of proteins, immune response (Se and Zn) and oxygen transport (Fe and Zn). Adequate quantities of these elements in diets is thus necessary for food security; inadequate intakes, or poor absorption in the gut due to e.g. diarrhoea, can lead to ‘hidden hunger’. It’s termed ‘hidden’ because the physical effects are not obvious, unlike the symptoms of protein or energy undernourishment, and because it is often hard to quantify the prevalence of such malnourishment in populations.
|Dried fish at a market in the capital city, Lilongwe|
Malawi is predominantly a subsistence economy in which households grow their own food. The dietary supply of elements is thus dependent on which crops households choose to grow and what those crops contain. Element concentrations in crops depend on the availability of elements in the soil: for example, in low-pH soils Se is predominantly found in forms unavailable for plant uptake, whereas in soils with pH >6.5 Se is generally soluble, mobile and readily available for plant uptake. There are limited data on crop composition in Malawi so we worked to fill this gap, collecting over 600 crop samples representing 97 food items for multi-element analysis by ICP-MS (Joy et al. 2014). We found that soil type affects crop composition, with maize and leafy vegetables from calcareous soils having greater Ca, Cu, Fe, Mg and Se concentrations than those grown on non-calcareous soils. Maize also had greater Zn in samples from calcareous soils, whereas leafy vegetables had greater Zn from non-calcareous soils.
The household survey
|Edward presenting the team’s work at Mzuzu University|
in northern Malawi
The FAO and World Bank have just published a book called ‘Analyzing Food Security Using Household Survey Data’ and at the recent Micronutrient Forum held in Addis Ababa, Ethiopia, I found that other research groups including IFPRI are doing similar work to us. It’s great to see the hard work now contributing to scientific knowledge as we write up, publish and present our findings.
Thanks for reading
Here are my references:
Eick F, Maleta K, Govasmark E, Duttaroy AK, Bjune AG (2009) Food intake of selenium and sulphur amino acids in tuberculosis patients and healthy adults in Malawi. Int J Tuberc Lung Dis 13: 1313–1315
Gibson RS, Bailey KB, Ampong Romano AB, Thomson CD (2011) Plasma selenium concentrations in pregnant women in two countries with contrasting soil selenium levels. J Trace Elem Med Bio 25:230–235
Gibson RS, Huddle JM (1998) Suboptimal zinc status in pregnant Malawian women: its association with low intakes of poorly available zinc, frequent reproductive cycling, and malaria. Am J Clin Nutr 67:702–709
Hurst R, Siyame EWP, Young SD, Chilimba ADC, Joy EJM, Black CR, Ander EL, Watts MJ, Chilima B, Gondwe J, Kang’ombe D, Stein AJ, Fairweather-Tait SJ, Gibson RS, Kalimbira AA, Broadley MR (2013) Soil-type influences human selenium status and underlies widespread selenium deficiency risks in Malawi. Sci Rep 3: 1425. DOI: 10.1038/srep01425
Joy, EJM, Broadley, MR, Young, SD, Black CR, Chilimba, ADC, Ander, EL, Barlow, TS and Watts, MJ*. (2014). A spatially refined food composition table for Malawi, Science Total Environment, (accepted Sept. 2014)
Siyame EWP, Hurst R, Wawer AA, Young SD, Broadley MR, Chilimba ADC, Ander EL, Watts MJ, Chilima B, Gondwe J, Kang'ombe D, Kalimbira A, Fairweather-Tait SJ, Bailey KB, Gibson RS (2013) A high prevalence of zinc- but not iron-deficiency among women in rural Malawi: a cross-sectional study. Int J Vitam Nutr Res 83: 176–187