Linkages between soil, crop, livestock, and human selenium status in Sub‐Saharan Africa: a scoping review

Abstract

Selenium (Se) is essential for human health, however, data on population Se status and agriculturenutrition-health linkages are limited in sub-Saharan Africa (SSA). The scoping review aims to identify linkages between Se in soils/crops, dietary Se intakes, and livestock and human Se status in SSA. Online databases, organisational websites and grey literature were used to identify articles. Articles were screened at title, abstract and full text levels using eligibility criteria. The search yielded 166 articles from which 112 were excluded during abstract screening and 54 full text articles were assessed for eligibility. The scoping review included 34 primary studies published between 1984 and 2021. The studies covered Se concentrations in soils (n = 7), crops (n = 9), animal tissues (n = 2), livestock (n = 3), and human Se status (n = 15). The evidence showed that soil/crop Se concentrations affected Se concentration in dietary sources, dietary Se intake and biomarkers of Se status. Soil types are a primary driver of human Se status and crop Se concentration correlates positively with biomarkers of Se dietary status. Although data sets of Se concentrations exist across the food system in SSA, there is limited evidence on linkages across the agriculture-nutrition nexus. Extensive research on Se linkages across the food chain is warranted.

A pilot survey of selenium status and its geospatial variation among children and women in three rural districts of Zimbabwe

“…Dietary Se deficiency is estimated to affect about 0.5 to 1 billion people across the world ( 30 , 31 ) and this may be exacerbated by climate change ( 32 ). Selenium deficiency is widespread among women and children in Africa ( 33 , 34 ), where a 28% prevalence of inadequate dietary Se intake was estimated ( 35 ). The Se status of populations varies markedly as a result of different geological, geochemical, and climatic factors ( 36 ).…”

Urine Se concentration poorly predicts plasma Se concentration at sub-district scales in Zimbabwe, limiting its value as a biomarker of population Se status

“…Previously, sub-optimal maize Se concentrations were observed in Malawi ( 56 ), South Africa ( 60 ), and Zambia ( 61 ). Cognizant of the similarities in geography and diet between Zimbabwe and these African countries ( 62 ) and also given that Zimbabwean soils are predominantly acidic ( 63–65 ), there is a high likelihood that the Zimbabwean maize crop has low Se concentrations ( 56 ), which could result in Se deficiency in the human population ( 66 ). Direct crop and dietary Se assessments are warranted to validate these findings.…”

Selenium Status of Southern Africa

“…Selenium biogeochemical cycling in an ecosystem is the main basis for understanding selenium characteristics in microbial systems, soil, and plants [30,31]. The levels of selenium in soils are mainly linked to plant selenium concentrations, and its availability in the soil varies depending on the texture, organic matter, type of soil, and amounts of rainfall in a region [3,12,32,33]. The presence of selenium in soil aids in the prevention of damage induced by climate change, mainly extreme temperatures, drought, and salinity of soils.…”

“…Selenium is a vital element of many enzymes and proteins; these proteins are called selenoproteins, which play a big role in making DNA and preventing cell damage and infections from pathogens [7,8]. Selenoproteins are actively involved in the metabolism of thyroid hormones and reproduction [9][10][11][12]. Selenium has also been documented to aid in the normal immune function of animals, and further studies on whether higher levels of selenium can stimulate the immune system are still ongoing [13,14].…”