Micronutrient Supplementation and Fortification Interventions on Health and Development Outcomes among Children Under-Five in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis

Abstract

Micronutrient deficiencies continue to be widespread among children under-five in low- and middle-income countries (LMICs), despite the fact that several effective strategies now exist to prevent them. This kind of malnutrition can have several immediate and long-term consequences, including stunted growth, a higher risk of acquiring infections, and poor development outcomes, all of which may lead to a child not achieving his or her full potential. This review systematically synthesizes the available evidence on the strategies used to prevent micronutrient malnutrition among children under-five in LMICs, including single and multiple micronutrient (MMN) supplementation, lipid-based nutrient supplementation (LNS), targeted and large-scale fortification, and point-of-use-fortification with micronutrient powders (MNPs). We searched relevant databases and grey literature, retrieving 35,924 papers. After application of eligibility criteria, we included 197 unique studies. Of note, we examined the efficacy and effectiveness of interventions. We found that certain outcomes, such as anemia, responded to several intervention types. The risk of anemia was reduced with iron alone, iron-folic acid, MMN supplementation, MNPs, targeted fortification, and large-scale fortification. Stunting and underweight, however, were improved only among children who were provided with LNS, though MMN supplementation also slightly increased length-for-age z-scores. Vitamin A supplementation likely reduced all-cause mortality, while zinc supplementation decreased the incidence of diarrhea. Importantly, many effects of LNS and MNPs held when pooling data from effectiveness studies. Taken together, this evidence further supports the importance of these strategies for reducing the burden of micronutrient malnutrition in children. Population and context should be considered when selecting one or more appropriate interventions for programming.

Keywords: effectiveness; efficacy; fortification; iron; lipid-based nutrient supplement; micronutrient; under-five; vitamin A; zinc.

Figure 1

Screening and selection of studies included in the meta-analysis. *Some studies had multiple intervention arms that included different intervention types.

Figure 2

Iron supplementation versus placebo/no intervention (efficacy studies) on the risk of anemia (hemoglobin concentration < 110 g/L).

Figure 3

Iron-folic acid supplementation versus placebo/no intervention (efficacy studies) on the risk of anemia (hemoglobin concentration < 110 g/L).

Figure 4

MMN supplementation versus placebo/no intervention (efficacy studies) on the risk of anemia (hemoglobin concentration < 110 g/L).

Figure 5

MNP supplementation versus placebo/no intervention (efficacy studies) on the risk of anemia (hemoglobin concentration < 110 g/L).

Figure 6

LNS supplementation versus placebo/no intervention (efficacy studies) on the risk of anemia (hemoglobin concentration < 110 g/L).

Figure 7

LNS supplementation versus placebo/no intervention (efficacy studies) on the risk of stunting (length-for-age z-score < −2).

Figure 8

Targeted fortification versus placebo/no intervention (efficacy studies) on the risk of anemia (hemoglobin concentration < 110 g/L).

Figure 9

Large-scale food fortification with iron versus placebo/no intervention (efficacy studies) on the risk of anemia (hemoglobin concentration < 110 g/L).

Figure 10

MNP supplementation versus placebo/no intervention (effectiveness studies) on the risk of anemia (hemoglobin concentration < 110 g/L).

Figure 11

LNS supplementation versus placebo/no intervention (effectiveness studies) on the risk of anemia (hemoglobin concentration < 110 g/L).