Bioequivalence of Micronutrient Powders to Conventional Fortification on Zinc Status of Children Aged 6-36 Months in Thika Informal Settlements, Kenya
Kiio, Juliana N.
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Corn Soy Blend (CSB) is the backbone of supplementation feeding for malnourished children. CSB however, has poor micronutrient bioavailability and may result into poor outcomes during nutrition recovery of the children. Micronutrient powders (MNPs) have a potential to improve micronutrient nutrition. Scientific evidence on the efficacy of MNPs in improving zinc (Zn) status among moderately malnourished children is scarce. This cluster randomized trial was designed to establish the bioequivalence of MNPs formulated as sprinklestm to conventional fortification in improving Zn status of moderately malnourished children aged 6-36 months in Thika informal settlements, Kenya. Secondary objectives were to determine the effect of Zn fortification on growth velocity, appetite and morbidity, to assess the predictors of Zn status at baseline and to establish the in vitro bio-accessibility of Zn. Twelve villages were randomized to four study groups. Three experimental groups received different formulations of MNPs added to CSB; multiple micronutrients (MMN) containing Zn (CSB-sprinkle-MMNZn), MMN without Zn (CSB-sprinkle-MMN) and Zn singly (CSB-sprinkle-Zn). The control group received conventionally Zn-fortified CSB containing MMN. CSB was prepared centrally in each of the participating villages and enrolled children brought there and fed daily on the assigned formulation. Standard tools were used to collect socio-demographic characteristics. Dietary practices were assessed using 24-hour recall and Food Frequency Questionnaires. Enrolled children underwent physical examination and anthropometric measurements. Hair and serum Zn levels were determined pre-post intervention. Daily consumption of CSB was monitored for a period of six months with monthly follow-up on dietary intake, anthropometric measurements and morbidity patterns. Sample size was calculated to show bioequivalence within ±20% limit. A total of 346 children (MUAC ≥11.5 - <12.5cm) were enrolled following informed consent; CSB-sprinkle-MMNZn (N=84), CSB-sprinkle-MMN (N=88), CSB-sprinkle-Zn (N=93) and control group (N=81). Analysis was by intention-to-treat. Strict adherence to assigned groups was observed and groups were similar in loss to follow-up and baseline characteristics except for a few differences. At baseline, 64.2% of the children were Zn deficient, Zn intake was sub-optimal for 95.7% of children. The prevalence of diarrhoea, acute respiratory tract infections and fever was 45.4%, 16.8% and 17.6% respectively. A mixed effects linear regression was used to model pre-post change in serum Zn levels, adjusting for age, sex and socio-economic status. Compared to control group, the change was significantly lower for CSB-sprinkle-MMN (β= -20.0μg/dL; 95% CI: -26.5, -13.5) and significantly higher for CSB-sprinkle-MMNZn (β=5.9 μg/dL; 95% CI: 0.5, 11.3). No significant difference was observed between CSB-sprinkle-ZN and control group (β=-2.1; 95% CI: -8.3; 4.2). Conventional fortification was not bioequivalent to MNPs in improving serum Zn levels (t-tests 95% CI: -2.2; 8.9 p>0.05). Kaplan Meier disease-free survival was not significantly different among study groups (log rank test; p>0.05). Change in appetite scores was not significantly different among study groups (mixed effects linear regression; p>0.05). In vitro Zn bio-accessibility in MNPs (26.05%) was not significantly different from control (24.07%) (t-test; p=0.7). MNPs were more effective in improving Zn status of malnourished children compared to conventional fortification and are therefore recommended for food supplementation programmes targeting urban poor. Further research on processing technologies to improve micronutrient bioavailability in CSB and on optimal home fortification for improved health outcomes is needed.