Selenium Concentration in Cattle, Dietary Selenium Intake in Children and Zinc Bio-Accessibility in Agronomically Biofortified Teff in Amhara Region, Ethiopia
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Date
2023-09
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Addis Ababa University
Abstract
Background:
Micronutrients are vitamins and minerals need by the body in small amount and play catalytic,
metabolic and structural role in the human body. However, the deficiency is prevalent in more
than a quarter of the world population and those from Sub-Saharan African countries are the
most affected. The deficiency has been implicated with increased risk of morbidity and mortality
and slow economic growth and human capital development. Iron (Fe), iodine (I), Zinc (Zn) and
folate are the most common micronutrient deficiencies. In addition, selenium (Se) for long time
was known for its toxicity. However, Se through selenoproteins, plays an important role to health
and metabolism of humans including thyroid metabolism, antioxidant defense system, and the
immune function. But the deficiency is estimated to affect 0.5 to 1 billion people worldwide. In
addition, Se deficiency in livestock has a direct and indirect impact to human nutrition by
affecting cattle reproduction and amount and quality of milk and meat. The distribution of Se in
nature is highly variable and Se concentration in soil is the main determinant factor. However,
food crops differ in their Se absorption and accumulation capacity suggesting that dietary pattern
and agro-ecology are significant contributors to the variation.
Objectives: To determine Se concentration in major food items and serum cattle and their feed
from areas known for contrasting Se concentration in the Amhara region. In addition, to evaluate
the Se and Zn bio-accessibility in dough and injera prepared from agronomically biofortified teff.
Methods: In a cross-sectional design, households with children in the age range 6 – 24 months
old were randomly selected from west Amhara (n= 78; west Gojam) and east Amhara (n= 75;
South Wollo) that are known for contrasting Se concentration in crop and soil. Dietary intake of
the children was estimated by employing a non-consecutive two day 24hr weighed food record
method. The sampling was repeated for 100% of children. In addition, breast milk samples (n=
121) and spot urine samples (n = 148), were collected. Blood samples were collected from
jugular vein of cattle (n= 224), centrifuged and the serum was separated. Moreover, the
corresponding feed samples of the cattle were collected. Se concentration in the food samples
were quantified after acid digestion, whereas in urine and cattle serum samples after dilution
using Inductively Coupled Plasma Mass spectroscopy (ICP-MS). Bioaccessibility of Zinc (Zn) in
dough and injera samples from Zn- biofortified teff was determined by Infogest invitro digestion
method.
Results: Selenium concentration in food, urine and breast milk samples from East Amhara had
significantly higher Se concentration than those from West Amhara. Similarly, there was
significantly lower Se concentration in cattle serum and feed samples from West Amhara than
samples from East Amhara (p<0.01). 31.5 % of children and 92 % of children had deficient Se
intake in east and west Amhara respectively, where as 62.5% cattle and 100 % of cattle showed
Se deficiency in east and west Amhara region. Urinary Se excretion accounted for 53% and 39%
of daily dietary Se intake in east Amhara and west Amhara, respectively. Se and Zn
biofortification of teff uplifted grain Se and Zn concentration by ten fold and 20 %,
respectively. Bio- accessibility of Zn in biofortified and control teff injera samples was not
significant (11.6 vs 10.9; p=0.79%). The bio-accessibility portion of Se was not detectable.
Conclusion: There was significant Se variation in foods, cattle serum and feed samples in
Amhara region affected by geographical location. This suggests the need for implementation of
targeted agronomic interventions that enhance Se concentration in the edible portion of plant
foods. In addition, the difference in Se concentration between foods warrants the need for
nutrition education to communities in the Se deficient areas to consider selection of foods with
relatively better Se concentration during food preparation.
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Keywords
Selenium Concentration in Cattle, Dietary Selenium Intake, Children and Zinc Bio-Accessibility, Agronomically Biofortified, Teff in Amhara Region, Ethiopia