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Titre : Assessment and optimization of dietary selenium intake in Kenya : exploration of biofortification as a solution to the hidden hunge

Beoordeling en optimalisatie van selenium inname via voeding in Kenia : verkenning van biofortificatie als een oplossing voor de verborgen honger

Auteur : NGIGI Peter Biu

Université de soutenance : Gent University

Grade : Doctor (PhD) in Applied Biological Sciences : Food Science and Nutrition 2019

Sommaire partiel
Selenium (Se) is an element for which trace amounts are essential for life. An adequate Se intake is crucial for antioxidant properties, redox regulation, and thyroid hormone regulation. Dietary Se intake impacts the immune system functioning, the response to viral infection, early growth and development, and the incidence of some cancers. Selenium deficiency therefore results in clinical disorders, many of them recognized today as public health problems globally. Low dietary Se intake is mainly caused by environmental conditions that inhibit soil Se mobility and availability for plants uptake resulting in low Se concentration in foodstuffs, coupled with monotonous diets based on a few staple foods. Yet, the complexity of how these factors interact and the mechanisms causing Se deficiency vary between regions and countries. Understanding these mechanisms is necessary to design suitable solutions and policies to address Se deficiency among affected communities. Selenium deficiency in Africa has previously been reported to be greatest in the East African region at 52%, with Kenya having a low dietary Se availability of 27 to 45 µg capita-1 day-1 and a risk of dietary Se inadequacy of 26 to 75 %. This thesis addressed Se deficiency in Kenya from a human nutrition, food science, environmental chemistry, and agricultural perspective. The main study region is Central Kenya Highlands, characterized by a variety of agricultural soils and a high population density relying on subsistence farming. Chapter 1 contributes to a better understanding of the inherent background of Se deficiency in Kenya. It describes the factors that potentially contribute to the existing risk of micronutrients deficiency. It highlights that food insecurity remains a major problem with 47% of Kenyans not being able to access sufficient food to meet daily nutrients requirements especially in rural areas. This leads to the emergence of micronutrient deficiencies, as reflected in the estimated high risk of dietary Se deficiency. Notably, Se research in the developing world was constrained by analytical limitations related to costs of equipment acquisition and maintenance, and the need for specific instrumental settings and sample preparation procedures not allowing Se to be determined in a same run as other minerals. This explains unavailability of foods’ Se concentration data in local food composition tables (FCTs) and consequently, its exclusion in past national nutrition surveys and interventions. Selenium is therefore not under consideration as part of health-targeted interventions and policies in Kenya. Thus, Chapter 1 elaborates on the complexity of the research problem and highlights the need to investigate the actual risk of dietary Se deficiency of the Kenyan population, and it explores potential interventional measures

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