Selenium Concentration in Cattle Serum and Fodder from Two Areas in Ethiopia with Contrasting Human Selenium Concentration.

INTRODUCTION: Selenium (Se) is an essential mineral for livestock health and productivity. In cattle, Se deficiency is associated with delayed conception, growth retardation, and increased morbidity and mortality. METHODS: We conducted a survey of cattle serum (n = 224) and feed (n = 81) samples from two areas with contrasting human and cereal grain Se concentration in Ethiopia. The fodder samples include stover, straw, hay and pasture grass. Se concentration of the samples were measured using inductively coupled plasma-mass spectrometry. RESULTS: Serum Se concentration ranged from 14.9 to 167.8 µg L-1 (median, 41.4 µg L-1). Cattle from East Amhara had significantly greater serum Se concentration compared to cattle from West Amhara (median: 68.4 µg L-1 vs 25.7 µg L-1; p < 0.001). Overall, 79.8% of cattle had Se deficiency (<81 µg L-1). All of the cattle from West Amhara were Se deficient compared with 62.5% of those from East Amhara. State of lactation of cows or age of cattle was not associated with serum Se concentration. The Se concentrations of feed samples ranged from 0.05 to 269.3 µg kg-1. Feed samples from East Amhara had greater Se concentration than samples from West Amhara. Cow serum and cattle feed Se concentrations showed strong spatially correlated variation, with a strong trend from East to West Amhara. CONCLUSIONS: This study shows that cattle Se deficiency is likely to be highly prevalent in Ethiopia, which will negatively affect the health and productivity of livestock. The deficiency appears to be geographical dependent. More extensive surveys to map Se concentration in soil-feed-livestock-human cycle are required in Ethiopia and elsewhere.

Modeling food fortification contributions to micronutrient requirements in Malawi using Household Consumption and Expenditure Surveys.

Large-scale food fortification may be a cost-effective intervention to increase micronutrient supplies in the food system when implemented under appropriate conditions, yet it is unclear if current strategies can equitably benefit populations with the greatest micronutrient needs. This study developed a mathematical modeling framework for comparing fortification scenarios across different contexts. It was applied to model the potential contributions of three fortification vehicles (oil, sugar, and wheat flour) toward meeting dietary micronutrient requirements in Malawi through secondary data analyses of a Household Consumption and Expenditure Survey. We estimated fortification vehicle coverage, micronutrient density of the diet, and apparent intake of nonpregnant, nonlactating women for nine different micronutrients, under three food fortification scenarios and stratified by subpopulations across seasons. Oil and sugar had high coverage and apparent consumption that, when combined, were predicted to improve the vitamin A adequacy of the diet. Wheat flour contributed little to estimated dietary micronutrient supplies due to low apparent consumption. Potential contributions of all fortification vehicles were low in rural populations of the lowest socioeconomic position. While the model predicted large-scale food fortification would contribute to reducing vitamin A inadequacies, other interventions are necessary to meet other micronutrient requirements, especially for the rural poor.

Selenium Deficiency Is Widespread and Spatially Dependent in Ethiopia.

: 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.

Urine selenium concentration is a useful biomarker for assessing population level selenium status.

Plasma selenium (Se) concentration is an established population level biomarker of Se status, especially in Se-deficient populations. Previously observed correlations between dietary Se intake and urinary Se excretion suggest that urine Se concentration is also a potentially viable biomarker of Se status. However, there are only limited data on urine Se concentration among Se-deficient populations. Here, we test if urine is a viable biomarker for assessing Se status among a large sample of women and children in Malawi, most of whom are likely to be Se-deficient based on plasma Se status. Casual (spot) urine samples (n = 1406) were collected from a nationally representative sample of women of reproductive age (WRA, n =741) and school aged children (SAC, n=665) across Malawi as part of the 2015/16 Demographic and Health Survey. Selenium concentration in urine was determined using inductively coupled plasma mass spectrometry (ICP-MS). Urinary dilution corrections for specific gravity, osmolality, and creatinine were applied to adjust for hydration status. Plasma Se status had been measured for the same survey participants. There was between-cluster variation in urine Se concentration that corresponded with variation in plasma Se concentration, but not between households within a cluster, or between individuals within a household. Corrected urine Se concentrations explained more of the between-cluster variation in plasma Se concentration than uncorrected data. These results provide new evidence that urine may be used in the surveillance of Se status at the population level in some groups. This could be a cost-effective option if urine samples are already being collected for other assessments, such as for iodine status analysis as in the Malawi and other national Demographic and Health Surveys.

A reconnaissance survey of farmers' awareness of hypomagnesaemic tetany in UK cattle and sheep farms.

Hypomagnesaemic tetany (HypoMgT) in ruminants is a physiological disorder caused by inadequate intake or impaired absorption of magnesium (Mg) in the gut. If it is not detected and treated in time, HypoMgT can cause the death of the affected animal. A semi-structured questionnaire survey was conducted from July 2016-2017 to assess farmers' awareness of HypoMgT in cattle and sheep in the UK. The questionnaire was distributed to farmers at farm business events and agricultural shows, and through a collaborative group of independent veterinary practices to their clients. Farmers were asked about (i) the incidence of presumed HypoMgT (PHT); (ii) their strategies to treat or prevent HypoMgT; (iii) mineral tests on animals, forage and soil, and (iv) farm enterprise type. A total of 285 responses were received from 82 cattle, 157 mixed cattle and sheep, and 46 sheep farmers, of whom 39% reported HypoMgT in their livestock, affecting 1-30 animals. Treatment and/or prevention against HypoMgT was reported by 96% respondents with PHT and 79% of those without. Mineral tests on animal, forage, and soil was conducted by 24%, 53%, and 66% of the respondents, respectively, regardless of PHT. There was a highly significant association between the use of interventions to tackle HypoMgT and the incidence of PHT (p < 0.01). The top three treatment/prevention strategies used were reported as being free access supplementation (149), in feed supplementation (59) and direct to animal treatments (drenches, boluses and injections) (45) although these did vary by farm type. Although some (9) reported using Mg-lime, no other pasture management interventions were reported (e.g., Mg-fertilisation or sward composition). Generally, the results indicate that UK farmers are aware of the risks of HypoMgT. A more integrated soil-forage-animal assessment may improve the effectiveness of tackling HypoMgT and help highlight the root causes of the problem.

The risk of selenium deficiency in Malawi is large and varies over multiple spatial scales.

Selenium (Se) is an essential human micronutrient. Deficiency of Se decreases the activity of selenoproteins and can compromise immune and thyroid function and cognitive development, and increase risks from non-communicable diseases. The prevalence of Se deficiency is unknown in many countries, especially in sub-Saharan Africa (SSA). Here we report that the risk of Se deficiency in Malawi is large among a nationally representative population of 2,761 people. For example, 62.5% and 29.6% of women of reproductive age (WRA, n = 802) had plasma Se concentrations below the thresholds for the optimal activity of the selenoproteins glutathione peroxidase 3 (GPx3; <86.9 ng mL-1) and iodothyronine deiodinase (IDI; <64.8 ng mL-1), respectively. This is the first nationally representative evidence of widespread Se deficiency in SSA. Geostatistical modelling shows that Se deficiency risks are influenced by soil type, and also by proximity to Lake Malawi where more fish is likely to be consumed. Selenium deficiency should be quantified more widely in existing national micronutrient surveillance programmes in SSA given the marginal additional cost this would incur.

Can selenium deficiency in Malawi be alleviated through consumption of agro-biofortified maize flour? Study protocol for a randomised, double-blind, controlled trial.

BACKGROUND: Micronutrient deficiencies including selenium (Se) are widespread in Malawi and potentially underlie a substantial disease burden, particularly among poorer and marginalised populations. Concentrations of Se in staple cereal crops can be increased through application of Se fertilisers - a process known as agronomic biofortification (agro-biofortification) - and this may contribute to alleviating deficiencies. The Addressing Hidden Hunger with Agronomy (AHHA) trial aims to establish the efficacy of this approach for improving Se status in rural Malawi. METHODS: A double-blind, randomised, controlled trial will be conducted in a rural community in Kasungu District, Central Region, Malawi. The hypothesis is that consumption of maize flour agro-biofortified with Se will increase serum Se concentration. We will recruit 180 women of reproductive age (WRA) (20-45 years) and 180 school-age children (SAC) (5-10 years) randomly assigned in a 1:1 ratio to receive either maize flour enriched through agro-biofortification with Se or a control flour not enriched with Se. Households will receive flour (330 g per capita per day) for 12 weeks. The primary outcome is Se concentration in serum (µg/L). Serum will be extracted from venous blood samples drawn at baseline (prior to flour distribution) and end-line. Selenium concentration will be measured by using inductively coupled plasma mass spectrometry. DISCUSSION: Findings will be communicated to policy stakeholders and participating communities and reported in peer-reviewed journals. TRIAL REGISTRATION: The Addressing Hidden Hunger with Agronomy (Malawi) trial is registered (5th March 2019; ISCRTN85899451).

Soil-type influences human selenium status and underlies widespread selenium deficiency risks in Malawi.

Selenium (Se) is an essential human micronutrient with critical roles in immune functioning and antioxidant defence. Estimates of dietary Se intakes and status are scarce for Africa although crop surveys indicate deficiency is probably widespread in Malawi. Here we show that Se deficiency is likely endemic in Malawi based on the Se status of adults consuming food from contrasting soil types. These data are consistent with food balance sheets and composition tables revealing that >80% of the Malawi population is at risk of dietary Se inadequacy. Risk of dietary Se inadequacy is >60% in seven other countries in Southern Africa, and 22% across Africa as a whole. Given that most Malawi soils cannot supply sufficient Se to crops for adequate human nutrition, the cost and benefits of interventions to alleviate Se deficiency should be determined; for example, Se-enriched nitrogen fertilisers could be adopted as in Finland.

Maize grain and soil surveys reveal suboptimal dietary selenium intake is widespread in Malawi.

Selenium is an essential element in human diets but the risk of suboptimal intake increases where food choices are narrow. Here we show that suboptimal dietary intake (i.e. 20-30 µg Se person(-1) d(-1)) is widespread in Malawi, based on a spatial integration of Se concentrations of maize (Zea mays L.) grain and soil surveys for 88 field sites, representing 10 primary soil types and >75% of the national land area. The median maize grain Se concentration was 0.019 mg kg(-1) (range 0.005-0.533), a mean intake of 6.7 µg Se person(-1) d(-1) from maize flour based on national consumption patterns. Maize grain Se concentration was up to 10-fold higher in crops grown on soils with naturally high pH (>6.5) (Eutric Vertisols). Under these less acidic conditions, Se becomes considerably more available to plants due to the greater solubility of Se((IV)) species and oxidation to Se((VI)).