Selenium Deficiency Is Widespread and Spatially Dependent in Ethiopia

Abstract

Selenium (Se) is an essential element for human health and livestock productivity. Globally, human Se status is highly variable, mainly due to the influence of soil types on the Se content of crops, suggesting the need to identify areas of deficiency to design targeted interventions. In sub-Saharan Africa, including Ethiopia, data on population Se status are largely unavailable, although previous studies indicated the potential for widespread Se deficiency. Serum Se concentration of a nationally representative sample of the Ethiopian population was determined, and these observed values were combined with a spatial statistical model to predict and map the Se status of populations across the country. The study used archived serum samples (n = 3269) from the 2015 Ethiopian National Micronutrient Survey (ENMS). The ENMS was a cross-sectional survey of young and school-age children, women and men. Serum Se concentration was measured using inductively coupled plasma mass spectrometry (ICPMS). The national median (Q1, Q3) serum Se concentration was 87.7 (56.7, 123.0) μg L−1. Serum Se concentration differed between regions, ranging from a median (Q1, Q3) of 54.6 (43.1, 66.3) µg L−1 in the Benishangul-Gumuz Region to 122.0 (105, 141) µg L−1 in the Southern Nations, Nationalities, and Peoples’ Region and the Afar Region. Overall, 35.5% of the population were Se deficient, defined as serum Se < 70 µg L−1. A geostatistical analysis showed that there was marked spatial dependence in Se status, with serum concentrations greatest among those living in North-East and Eastern Ethiopia and along the Rift Valley, while serum Se concentrations were lower among those living in North-West and Western Ethiopia. Selenium deficiency in Ethiopia is widespread, but the risk of Se deficiency is highly spatially dependent. Policies to enhance Se nutrition should target populations in North-West and Western Ethiopia.

The nutritional quality of cereals varies geospatially in Ethiopia and Malawi

“…In parts of the Amhara region of Ethiopia, nutritionally important variation in the grain Se concentration of teff (Eragrostis tef (Zucc.) Trotter) and wheat (Triticum aestivum L.) was associated with soil and landscape covariates at distances extending further than 100 km, which is similar to patterns seen among human biomarkers of Se dietary status 22,23 . In Malawi, human Se dietary status was associated with variation in the grain Se concentration in maize (Zea mays L.) at localized scales 4,5,15,[24][25][26] .…”

“…Links between grain micronutrient concentration and a dietary outcome were observed for Se, for which there is a reliable biomarker of dietary status 7,13 . Biomarker data for Se for 321 enumeration areas in Ethiopia 23 and 101 enumeration areas in Malawi 24 are available from recent National Micronutrient Surveys. For each enumeration area, the nearest grain sample site for any crop type was identified.…”

“…Determining the links between a dietary biomarker of status and grain micronutrient concentration focused here on Se, for which there is a reliable biomarker of dietary status 13 ; this is not the case for Zn 7 and the other micronutrients analysed in this study. Data on the concentration of Se in the blood of women of reproductive age were available from micronutrient surveys in Ethiopia (serum 23 ) and Malawi (plasma 24 ). Mean concentrations were computed for each enumeration area available-321 in Ethiopia and 101 in Malawi-for which the latitude and longitude for each enumeration area centroid were available.…”

Communicating uncertainties in spatial predictions of grain micronutrient concentration

“…The findings of this study complement work that has been done on cartography and visualisation for spatial information (Kunz et al, 2011;Beven et al, 2015). Our findings show the importance of finding cartographic solutions to represent probability information and to develop interactive methods for interpretation in a geographic information system (GIS) environment (e.g.…”

Biofortified Maize Improves Selenium Status of Women and Children in a Rural Community in Malawi: Results of the Addressing Hidden Hunger With Agronomy Randomized Controlled Trial

“…In conclusion, the present study provides proof of concept that the Se status of women and children in rural Malawi can be improved using an agronomic biofortification approach, and further work is now required to establish the cost-effectiveness and feasibility of scaling this technology, including in other countries in sub-Saharan Africa where Se deficiency is prevalent (32,46). was provided by adult participants and the legal guardian of child participants.…”