Vitamin A deficiency has declined in Malawi, but with evidence of elevated vitamin A in children

Abstract

Background: Reduction of vitamin A deficiency (VAD) in Malawi coincided with introduction of vitamin A-fortified staple foods, alongside continued biannual high-dose vitamin A supplementation (VAS).

Objective: We describe coverage of vitamin A interventions and vitamin A status in the 2015-2016 Malawi Micronutrient Survey.

Methods: Food samples and biospecimens were collected within a representative household survey across 105 clusters. Retinol was measured using ultraviolet excitation fluorescence (sugar) and photometric determination (oil). Preschool children (PSC, aged 6-59 mo, n = 1102), school-age children (SAC, aged 5-14 y, n = 758), nonpregnant women (n = 752), and men (n = 219) were initially assessed for vitamin A status using retinol binding protein (RBP) and modified relative dose response (MRDR). Randomly selected fasted MRDR participants (n = 247) and nonfasted women and children (n = 293) were later assessed for serum retinol, retinyl esters, and carotenoids. Analyses accounted for complex survey design.

Results: We tested sugar and oil samples from 71.8% and 70.5% of the households (n = 2,112), respectively. All of the oil samples and all but one of the sugar samples had detectable vitamin A. National mean retinol sugar and oil contents were 6.1 ± 0.7 mg/kg and 6.6 ± 1.4 mg/kg, respectively. Receipt of VAS in the previous 6 mo was reported by 68.0% of PSC. VAD prevalence (RBP equivalent to <0.7µmol retinol/L) was 3.6% in PSC, and <1% in other groups. One woman and no children had MRDR ≥0.060 indicating VAD. Among fasted PSC and SAC, 18.0% (95% CI: 6.4, 29.6) and 18.8% (7.2, 30.5) had >5% of total serum vitamin A as retinyl esters, and 1.7% (0.0, 4.1) and 4.9% (0.0, 10.2) had >10% of total serum vitamin A as retinyl esters. Serum carotenoids indicated recent intake of vitamin A-rich fruits and vegetables.

Conclusions: Near elimination of VAD in Malawi is a public health success story, but elevated levels of vitamin A among children suggests that vitamin A interventions may need modification.

Keywords: carotenoids; fortification; overlapping interventions; retinyl esters; vitamin A.

FIGURE 1

Participant flow chart from the 2015–2016 Malawi Micronutrient Survey and supplementary vitamin A biomarker analysis. Men (20–54 y); MRDR, modified relative dose response; PSC, preschool age children (6–59 mo); RBP, retinol binding protein; SAC, school age children (5–14 y); WRA, women of reproductive age (15–49 y).