Dataset Information

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

ABSTRACT: 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)).

SUBMITTER: Chilimba AD

PROVIDER: S-EPMC3216559 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

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

Chilimba Allan D C AD Young Scott D SD Black Colin R CR Rogerson Katie B KB Ander E Louise EL Watts Michael J MJ Lammel Joachim J Broadley Martin R MR

Scientific reports 20110823

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 ...[more]

PMID: 22355591

Similar Datasets

Project description:Dietary zinc (Zn) deficiency is widespread globally, and in particular among people in sub-Saharan Africa (SSA). In Malawi, dietary sources of Zn are dominated by maize and spatially dependent variation in grain Zn concentration, which will affect dietary Zn intake, has been reported at distances of up to ~ 100 km. The aim of this study was to identify potential soil properties and environmental covariates which might explain this longer-range spatial variation in maize grain Zn concentration. Data for maize grain Zn concentrations, soil properties, and environmental covariates were obtained from a spatially representative survey in Malawi (n = 1600 locations). Labile and non-labile soil Zn forms were determined using isotopic dilution methods, alongside conventional agronomic soil analyses. Soil properties and environmental covariates as potential predictors of the concentration of Zn in maize grain were tested using a priori expert rankings and false discovery rate (FDR) controls within the linear mixed model (LMM) framework that informed the original survey design. Mean and median grain Zn concentrations were 21.8 and 21.5 mg kg-1, respectively (standard deviation 4.5; range 10.0-48.1). A LMM for grain Zn concentration was constructed for which the independent variables: soil pH(water), isotopically exchangeable Zn (ZnE), and diethylenetriaminepentaacetic acid (DTPA) extractable Zn (ZnDTPA) had predictive value (p < 0.01 in all cases, with FDR controlled at < 0.05). Downscaled mean annual temperature also explained a proportion of the spatial variation in grain Zn concentration. Evidence for spatially dependent variation in maize grain Zn concentrations in Malawi is robust within the LMM framework used in this study, at distances of up to ~ 100 km. Spatial predictions from this LMM provide a basis for further investigation of variations in the contribution of staple foods to Zn nutrition, and where interventions to increase dietary Zn intake (e.g. biofortification) might be most effective. Other soil and landscape factors influencing spatially dependent variation in maize grain Zn concentration, along with factors operating over shorter distances such as choice of crop variety and agronomic practices, require further exploration beyond the scope of the design of this survey.

Project description:BackgroundOsteoporosis, characterized by reduced bone mineral density (BMD) increases the risk of all-cause mortality. Assessments of whether dietary selenium intake is related to bone health are scarce, with few relevant studies limited by a small sample size. The aim of the present study was to investigate the association between dietary selenium intake and BMD levels in the National Health and Nutrition Examination Survey (NHANES) database.MethodsWe extracted and aggregated data from 4 cycles of the NHANES [2005-2010, 2013-2014]. Dietary selenium intake was obtained from 24-hour dietary recall interviews. BMD measurement, including the femur, femur neck, trochanter and intertrochanter of the femur, and lumbar spine, was performed using dual-energy X-ray absorptiometry. The multivariable linear regression model for the association between dietary selenium intake and BMD and the generalized additive model (GAM) for the dose-response relationship were used.ResultsA total of 21,939 participants were included. The mean age was 40.68±22.42 years, and 51.28% were male. In the multivariable adjustment model, participants with the highest quintiles of dietary selenium intake (Q5) were associated with increased BMD levels in the total femur (β=0.014, 95% CI: 0.008-0.020, P<0.001), femur neck (β=0.010, 95% CI: 0.004-0.016, P=0.001), trochanter (β=0.011, 95% CI: 0.005-0.017, P<0.001), intertrochanter (β=0.017, 95% CI: 0.010-0.025, P<0.001), and lumbar spine (β=0.013, 95% CI: 0.005-0.020, P<0.001) compared with those in quintile 1 (Q1). The dose-response relationship showed an inverted U-shape relationship between dietary selenium intake and BMD levels (P for nonlinearity <0.05). Participants tended to have increased levels of BMD as the dietary selenium intake increased when dietary selenium was below the turning point, and then a negative relationship was observed when dietary intake was higher than the turning point.ConclusionsOur study indicated that dietary selenium intake exhibited an inverted U-shape trend in relation to BMD levels, which demonstrates the need for selenium status in the body to be considered when discussing the role of dietary selenium intake in BMD. Future studies are needed to confirm these findings and explore the underlying biological mechanism.

Project description:The spatial distribution of the root system through the soil profile has an impact on moisture and nutrient uptake by plants, affecting growth and productivity. The spatial distribution of the roots, soil moisture, and fertility are affected by tillage practices. The combination of high soil density and the presence of a soil plow pan typically impede the growth of maize (Zea mays L.).We investigated the spatial distribution coordination of the root system, soil moisture, and N status in response to different soil tillage treatments (NT: no-tillage, RT: rotary-tillage, SS: subsoiling) and the subsequent impact on maize yield, and identify yield-increasing mechanisms and optimal soil tillage management practices. Field experiments were conducted on the Huang-Huai-Hai plain in China during 2011 and 2012. The SS and RT treatments significantly reduced soil bulk density in the top 0-20 cm layer of the soil profile, while SS significantly decreased soil bulk density in the 20-30 cm layer. Soil moisture in the 20-50 cm profile layer was significantly higher for the SS treatment compared to the RT and NT treatment. In the 0-20 cm topsoil layer, the NT treatment had higher soil moisture than the SS and RT treatments. Root length density of the SS treatment was significantly greater than density of the RT and NT treatments, as soil depth increased. Soil moisture was reduced in the soil profile where root concentration was high. SS had greater soil moisture depletion and a more concentration root system than RT and NT in deep soil. Our results suggest that the SS treatment improved the spatial distribution of root density, soil moisture and N states, thereby promoting the absorption of soil moisture and reducing N leaching via the root system in the 20-50 cm layer of the profile. Within the context of the SS treatment, a root architecture densely distributed deep into the soil profile, played a pivotal role in plants' ability to access nutrients and water. An optimal combination of deeper deployment of roots and resource (water and N) availability was realized where the soil was prone to leaching. The correlation between the depletion of resources and distribution of patchy roots endorsed the SS tillage practice. It resulted in significantly greater post-silking biomass and grain yield compared to the RT and NT treatments, for summer maize on the Huang-Huai-Hai plain.

Dataset Information

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

Publications

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

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets