efficacy of yellow cassava to improve vitamin a status of kenyan school children

Conditions: Vitamin A Deficiency

Summary: the overall aim of the project is to provide proof-of-principle that biofortification of cassava with vitamin a is a viable strategy to improve vitamin a status of deficient populations.

rationale: vitamin a deficiency is still common in developing countries and has been proven difficult to combat. a promising approach is to replace common crops with varieties that are naturally richer in vitamin a, which is referred to as biofortification. for cassava, yellow β-carotene rich varieties have recently been introduced in kenya, and these varieties are now ready to be tested for their efficacy to improve vitamin a status in humans. objective: the primary objective is to measure the effect of daily consumption of provitamin a biofortified cassava (providing 50% of the age-specific rda) on vitamin a status in children aged 5-13 years with mild to moderate vitamin a deficiency in kenya. to determine the bioefficacy of provitamin a carotenoids from biofortified cassava relative to that of a daily b-carotene supplement (comparison with positive control group). secondary objectives are: 1) to measure the effect of the intervention on immune function indicators and morbidity; 2) to determine to what degree the serum retinol response to the intervention depends on serum concentrations of retinol and zinc at baseline; 3) to determine the effect of the intervention on functional indicators such as dark adaptation capacity, gut integrity, hematology indicators and thyroid status; 4) to determine the mediating effect of snp's in the bcmo1 gene on treatment outcome. study design \& study population : in this randomized controlled trial, school children aged 5-13 years living in the kibwezi area, kenya. children will be selected from three (or four) primary schools in the area that have been pre-selected based on the prevalence of vitamin a deficiency, location and willingness to participate. intervention: after screening for eligibility and a 2-week run-in period (n=360) children will be randomly allocated to three different treatments: 1) 400 g of yellow cassava providing \~50% of the rda for vitamin a; and a placebo capsule; 2) 400 g of white cassava; and a placebo capsule; 3) 400 g of white cassava and a capsule containing 100 rae of all-trans β-carotene. main study parameters/endpoints: the main outcome measure will be differences in serum retinol concentrations between groups. other outcome measures include other vitamin a status indicators (β-carotene, retinol binding protein, transthyretin), immune function indicators, dark adaptation, iron status indicators, anthropometrics, gut integrity, and thyroid function.

Eligibility criteria:
inclusion criteria: * low vitamin a status (retinol binding protein (rbp) at the lowest end of the distribution will be included in the study) exclusion criteria: * history or signs of infectious or systemic diseases (e.g. tuberculosis, sickle cell anaemia) * anaemia, malaria or acute inflammation at the day of baseline measurements

Keywords: vitamin a deficiency biofortification cassava b-carotene school children kenya