Abstract
Vitamin A supplementation (VAS) in 6-59-month-old children is recommended but its sustainability is currently questioned. In Senegal, available data suggest that VAS should be maintained, but geographic and age-related specificities need to be addressed to better implement and target VAS programming. The objective of this comparative cross-sectional study, conducted in urban settings of Dakar, was to compare the vitamin A liver stores (VALS) assessed using the modified-relative dose response (MRDR) test between supplemented and non-supplemented 9–23 month-old children and to study their relationship with VAS. The supplemented group (n = 119) received VAS (either 100 000 UI or 200 000 UI) 2 to 6 months before evaluation while the non-supplemented group (n = 110) had not received VAS during the past 6 months. In addition to MRDR, serum retinol concentrations (SR), and biomarkers of subclinical inflammation were measured. Children’s health-related data and feeding patterns were collected. Mean MRDR values (VAS: 0.030 ± 0.017, non-VAS: 0.028 ± 0.016, P = 0.389) and inflammation-adjusted SR (VAS: 1.34 ± 0.37, non-VAS: 1.3 ± 0.35, P = 0.515) of children were adequate. Low prevalence of VALS (VAS: 5.2%, non-VAS: 5.4%) and inflammation-adjusted VAD (VAS: 2.6%, non-VAS: 0.9%) were detected despite high presence of infections and inflammation. Children were mostly still being breastfed (VAS: 85.7%, non-VAS: 77.3%) and complementary feeding indicators were similar in both groups. Only breastfeeding was associated with VALS and was found to reduce by 76% at least, the odds of VAD (adjusted OR = 0.24, 95% CI: 0.07–0.8, P = 0.020). Based on MRDR values, VAS was not related to improved VALS and SR as well as VAD reduction among these children with adequate VALS. Reinforcing breastfeeding advocacy and morbidity prevention/control are essential in this setting. Scaling-back VAS in this subpopulation should be examined regarding the risk of hypervitaminosis A after an evaluation of dietary vitamin A intake sufficiency and a more quantitative assessment of VALS.
Highlights
Vitamin A deficiency (VAD) is a serious public health concern throughout the developing world, affecting 190 million preschool-age children and leading to many deleterious health consequences, including morbidity and mortality [1,2,3]
The aim of this work was to compare vitamin A liver stores (VALS) assessed using the modified-relative dose response (MRDR) test between supplemented and non-supplemented 9–23 month old Senegalese children living in Dakar and to study the relationship with vitamin A supplementation (VAS)
The sample size determination was based on data from Tanumihardjo et al [41] in Indonesian children (0.6 to 6.6 years) where the proportion of MRDR values 0.060 was 6% in a VAS plus deworming group compared to a control group (22%), four weeks after administration of supplements
Summary
Vitamin A deficiency (VAD) is a serious public health concern throughout the developing world, affecting 190 million preschool-age children and leading to many deleterious health consequences, including morbidity and mortality [1,2,3]. Strategies to prevent and control VAD and its consequences include dietary diversification, food fortification (either mandatory or voluntary), biofortification of staple foods and periodic high-dose vitamin A supplementation (VAS) [3]. The World Health Organization (WHO) recommendation of high-dose VAS as a public health intervention to reduce morbidity and mortality in infants and children 6–59 months of age in settings where VAD is prevalent [13] was renewed in 2011 [14]. These guidelines are based on the reported effectiveness of VAS in reducing childhood mortality [15,16]. The Global Alliance for Vitamin A (GAVA) as well as others suggested that VAS should be pursued in countries or areas where VAD is still a public health problem until there is evidence of controlled VAD (i.e., VAD 10%) and children have a sustained and adequate VA intake from diet and other interventions [26,27,28,29]
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