ABSTRACT
Objectives: To measure the effect of daily consumption of provitamin A-biofortified cassava on vitamin A status in children aged 5-13 years. Methods: Mild-to-moderate vitamin A deficient children (n=342) were randomly allocated to groups receiving: 1) 375 g of white cassava and placebo supplement; 2) 375 g of white cassava and a supplement of β-carotene (1,054 μg); 3) 375 g of biofortified cassava and placebo supplement. Children received the intervention 6 days/week for 18.5 weeks. Field staff and participants were blinded to supplementation. Cooked cassava was mashed with salt and 4 g of oil per portion. Biofortified cassava supplied 208 μg RAE, which is ~50% of the age-specific estimated average requirement for vitamin A for children. The primary endpoint was serum retinol concentration and secondary endpoint was serum β-carotene concentration, both at end of intervention; in the analysis, we adjusted for sex and serum concentrations at baseline of retinol, C-reactive protein and α1-acid-glycoprotein. Results: Complete data were collected for 337 children. Compliance to cassava feeding was similar between treatment groups. Preliminary results showed that consumption of biofortified cassava and β-carotene supplementation resulted in a similar increase in retinol concentrations (for both interventions, mean: 0.81 μmol/L versus 0.77 μmol/L; difference, 95% CI: 0.04 μmol/L, 0.00─0.07 μmol/L) but in a different increase in serum β-carotene concentration (for β-carotene supplement group, mean: 0.25 μmol/L (95% CI: 0.17─0.33), for biofortified cassava group, mean: 0.81 μmol/L (95% CI: 0.73-0.88)) Conclusions: Provitamin A-biofortified cassava improves the vitamin A status of primary school children in Kenya.
ABSTRACT
Objectives: To assess the diagnostic performance of serum concentrations of retinol-binding protein (RBP), transthyretin, retinol concentration measured by fluorometry and RBP:transthyretin molar ratio, either alone or in combination, to estimate the prevalence of vitamin A deficiency (serum retinol concentration <0.70 μmol/L measured by high-performance liquid chromatography(HPLC)). Methods: A cross-sectional study was conducted in 15 primary schools in Kibwezi and Makindu districts in Eastern province, Kenya in June 2010 with 375 schoolchildren (6-12 years), 25 randomly selected from each school by lot quality assurance sampling. Results: Complete data were collected for 372 children. Mean serum concentration of retinol (HPLC), RBP and transthyretin were 0.87 (SD 0.19) µmol/L, 0.67 (SD 0.17) µmol/L and 3.0 (SD 0.62) µmol/L. The mean RBP: Transthyretin molar ratio was 0.23. The prevalence of vitamin A deficiency measured with HPLC was 18%. Transthyretin and RBP showed the largest area under the curve (AUCs 0.96 and 0.93, respectively). Logistic regression resulted in a model predicting vitamin A deficiency based on RBP, transthyretin and C-reactive protein (AUC: 0.98) and prevalence depending cutpoints for the linear predictor were calculated. Conclusions: Combination of transthyretin, RBP and C-reactive protein in a linear predictor showed excellent diagnostic performance in assessing vitamin A status, and has great potential to eventually replace serum retinol concentration measured by HPLC as the preferred method to assess the population burden of vitamin A deficiency. Further research is needed to confirm whether this linear predictor yields similar results in different populations and laboratories. Our methodology can be widely applied for other diagnostic aims.