SEGH Articles

The Joy's of PhD research in two countries

06 October 2014
Edwards project aim 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. He has been conducting fieldwork in Malawi during 2012-14.

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.

Malawi hasn’t witnessed widespread famine since 2005, although certain regions are prone to food shortages due to both drought and flooding. But it may be that hidden hunger is widespread and that deficiencies of certain minerals and vitamins are a major health burden. There is evidence to suggest this is the case, for example with Se deficiency (Gibson 2011; Eick 2009; Hurst 2013) and Zn deficiency (Gibson 1998; Siyame 2013); but there is no data at the national level.

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. submitted). 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.

To find out what crops households are growing and what foods they are eating, the Malawi Household Survey (World Bank and Malawi Government) has proved a valuable resource. In this survey, >12,500 households were asked what foods they consumed over the last seven days. We are working to match this data to our composition data to generate dietary mineral supply estimates by region and soil type. One of our early findings is the critical importance of small fish in meeting Ca, Se and Zn requirements. Most fish production is from Lake Malawi, a Rift Valley lake that runs much of the length of the country. It’s sometimes known as the Calendar Lake as it’s roughly 365 mile long and 52 miles wide. Fish are sundried before traders take them inland. Although fish is a vital source of minerals in the diet, households require some cash to purchase them. It will be very interesting to see the relationship between household income and consumption of fish. 

Dried fish at a market in the capital city, Lilongwe


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.

Edward presenting the team’s work at Mzuzu University in northern Malawi


The last couple of years have been a steep learning curve: 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 September. 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. And the Malawi Ministries of Agriculture and Health have been very supportive of the work. Hopefully the outputs will be useful to them, for example in developing fertiliser policies and targeting nutrition strategies.


by Edward Joy, PhD researcher University of Nottingham-BGS


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

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

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, (in press)



Keep up to date

SEGH Events

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

  • Status, source identification, and health risks of potentially toxic element concentrations in road dust in a medium-sized city in a developing country 2017-09-19


    This study aims to determine the status of potentially toxic element concentrations of road dust in a medium-sized city (Rawang, Malaysia). This study adopts source identification via enrichment factor, Pearson correlation analysis, and Fourier spectral analysis to identify sources of potentially toxic element concentrations in road dust in Rawang City, Malaysia. Health risk assessment was conducted to determine potential health risks (carcinogenic and non-carcinogenic risks) among adults and children via multiple pathways (i.e., ingestion, dermal contact, and inhalation). Mean of potentially toxic element concentrations were found in the order of Pb > Zn > Cr(IV) > Cu > Ni > Cd > As > Co. Source identification revealed that Cu, Cd, Pb, Zn, Ni, and Cr(IV) are associated with anthropogenic sources in industrial and highly populated areas in northern and southern Rawang, cement factories in southern Rawang, as well as the rapid development and population growth in northwestern Rawang, which have resulted in high traffic congestion. Cobalt, Fe, and As are related to geological background and lithologies in Rawang. Pathway orders for both carcinogenic and non-carcinogenic risks are ingestion, dermal contact, and inhalation, involving adults and children. Non-carcinogenic health risks in adults were attributed to Cr(IV), Pb, and Cd, whereas Cu, Cd, Cr(IV), Pb, and Zn were found to have non-carcinogenic health risks for children. Cd, Cr(IV), Pb, and As may induce carcinogenic risks in adults and children, and the total lifetime cancer risk values exceeded incremental lifetime.

  • Erratum to: Preliminary assessment of surface soil lead concentrations in Melbourne, Australia 2017-09-11
  • In vivo uptake of iodine from a Fucus serratus Linnaeus seaweed bath: does volatile iodine contribute? 2017-09-02


    Seaweed baths containing Fucus serratus Linnaeus are a rich source of iodine which has the potential to increase the urinary iodide concentration (UIC) of the bather. In this study, the range of total iodine concentration in seawater (22–105 µg L−1) and seaweed baths (808–13,734 µg L−1) was measured over 1 year. The seasonal trend shows minimum levels in summer (May–July) and maximum in winter (November–January). The bathwater pH was found to be acidic, average pH 5.9 ± 0.3. An in vivo study with 30 volunteers was undertaken to measure the UIC of 15 bathers immersed in the bath and 15 non-bathers sitting adjacent to the bath. Their UIC was analysed pre- and post-seaweed bath and corrected for creatinine concentration. The corrected UIC of the population shows an increase following the seaweed bath from a pre-treatment median of 76 µg L−1 to a post-treatment median of 95 µg L−1. The pre-treatment UIC for both groups did not indicate significant difference (p = 0.479); however, the post-treatment UIC for both did (p = 0.015) where the median bather test UIC was 86 µg L−1 and the non-bather UIC test was 105 µg L−1. Results indicate the bath has the potential to increase the UIC by a significant amount and that inhalation of volatile iodine is a more significant contributor to UIC than previously documented.