Effect of zinc supplementation on growth of low birth weight infants aged 1-6 mo in Ardabil, Iran

Enteral Zinc Supplementation in Preterm or Low Birth Weight Infants: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVES

Evidence on the effect of zinc supplementation on health outcomes in preterm or low birth weight (LBW) infants is unclear. We estimated the effect of enteral zinc versus no zinc supplementation in human milk fed preterm or LBW infants on mortality, growth, morbidities, and neurodevelopment.

METHODS

Data sources include PubMed, Cochrane Central and Embase databases through March 24, 2021. Study selection was randomized or quazi-experimental trials. Two reviewers independently screened, extracted data, and assessed quality. We reported pooled relative risks (RR) for categorical outcomes, and mean differences (MD) for continuous outcomes.

RESULTS

Fourteen trials with 9940 preterm or LBW infants were included. Moderate to low certainty evidence showed that enteral zinc supplementation had little or no effect on mortality (risk ratio 0.73, 95% confidence interval [CI] 0.46 to 1.16), but increased weight (MD 378.57, 95% CI 275.26 to 481.88), length (MD 2.92, 95% CI 1.53 to 4.31), head growth (MD 0.56, 95% CI 0.23 to 0.90), and decreased diarrhea (RR 0.81; 95% CI 0.68 to 0.97). There was no effect on acute respiratory infections, bacterial sepsis, and psychomotor development scores. The effect of zinc supplementation on mental development scores is inconclusive. There was no evidence of serious adverse events. Eight trials had some concerns or high risk of bias, small-sized studies, and high heterogeneity between trials led to moderate to very low certainty of evidence.

CONCLUSIONS

Zinc supplementation in preterm or LBW infants have benefits on growth and diarrhea prevention. Further research is needed to generate better quality evidence.

Effect of enteral zinc supplementation on growth and neurodevelopment of preterm infants: a systematic review and meta-analysis

OBJECTIVE

To evaluate effect of enteral zinc supplementation on growth and neurodevelopmental outcomes of preterm infants.

STUDY DESIGN

A systematic review and meta-analysis of randomized-controlled trials (RCTs) examining growth and neurodevelopmental outcomes after zinc supplementation in preterm infants.

RESULTS

Of eight RCTs involving 742 infants included, seven reported growth anthropometrics at 3-6 months corrected age (CA) and two reported neurodevelopmental outcomes at 6-12 months CA. Zinc supplementation was associated with increased weight z-score (weighted mean difference (WMD) = 0.50; 95% CI 0.23-0.76, heterogeneity I2 = 89.1%; P < 0.01), length z-score (WMD = 1.12; 95% CI 0.63-1.61, heterogeneity I2 = 96.0%; P < 0.01) and motor developmental score (WMD = 9.54; 95% CI 6.6-12.4 heterogeneity I2 = 0%; P = 0.52). There was no effect on head circumference and total developmental score. Evidence is "moderate" certainty for weight and length and "very low" certainty for neurodevelopment.

CONCLUSION

Zinc supplementation may enhance weight gain and linear growth in preterm infants. There is a lack of data about relationship between zinc supplementation and neurodevelopment.

Role of zinc in neonatal growth and brain growth: review and scoping review

This manuscript includes (1) a narrative review of Zinc as an essential nutrient for fetal and neonatal growth and brain growth and development and (2) a scoping review of studies assessing the effects of Zinc supplementation on survival, growth, brain growth, and neurodevelopment in neonates. Very preterm infants and small for gestational age infants are at risk for Zinc deficiency. Zinc deficiency can cause several complications including periorificial lesions, delayed wound healing, hair loss, diarrhea, immune deficiency, growth failure with stunting, and brain atrophy and dysfunction. Zinc is considered essential for oligodendrogenesis, neurogenesis, neuronal differentiation, white matter growth, and multiple biological and physiological roles in neurobiology. Data support the possibility that the critical period of Zinc delivery for brain growth in the mouse starts at 18 days of a 20-21-day pregnancy and extends during lactation and in human may start at 26 weeks of gestation and extend until at least 44 weeks of postmenstrual age. Studies are needed to better elucidate Zinc requirement in extremely low gestational age neonates to minimize morbidity, optimize growth, and brain growth, prevent periventricular leukomalacia and optimize neurodevelopment. IMPACT: Zinc is essential for growth and brain growth and development. In the USA, very preterm small for gestational age infants are at risk for Zinc deficiency. Data support the possibility that the critical period of Zinc delivery for brain growth in the mouse starts at 18 days of a 20-21-day pregnancy and extends during lactation and in human may start at 26 weeks' gestation and extend until at least 44 weeks of postmenstrual age. Several randomized trials of Zinc supplementation in neonates have shown improvement in growth when using high enough dose, for long duration in patients likely to or proven to have a Zinc deficiency. Studies are needed to better elucidate Zinc requirement in extremely low gestational age neonates to minimize morbidity, optimize growth and brain growth, prevent periventricular leukomalacia and optimize neurodevelopment.

Enteral zinc supplementation for prevention of morbidity and mortality in preterm neonates

BACKGROUND

Preterm and low birth weight infants are born with low stores in zinc, which is a vital trace element for growth, cell differentiation and immune function. Preterm infants are at risk of zinc deficiency during the postnatal period of rapid growth. Systematic reviews in the older paediatric population have previously shown that zinc supplementation potentially improves growth and positively influences the course of infectious diseases. In paediatric reviews, the effect of zinc supplementation was most pronounced in those with low nutritional status, which is why the intervention could also benefit preterm infants typically born with low zinc stores and decreased immunity.

OBJECTIVES

To determine whether enteral zinc supplementation, compared with placebo or no supplementation, affects important outcomes in preterm infants, including death, neurodevelopment, common morbidities and growth.

SEARCH METHODS

Our searches are up-to-date to 20 February 2020. For the first search, we used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL 2017, Issue 8), MEDLINE via PubMed (1966 to 29 September 2017), Embase (1980 to 29 September 2017), and CINAHL (1982 to 29 September 2017). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials (RCTs) and quasi-RCTs. We ran an updated search from 1 January 2017 to 20 February 2020 in the following databases: CENTRAL via CRS Web, MEDLINE via Ovid, and CINAHL via EBSCOhost.

SELECTION CRITERIA

We included RCTs and quasi-RCTs that compared enteral zinc supplementation versus placebo or no supplementation in preterm infants (gestational age < 37 weeks), and low birth weight babies (birth weight < 2500 grams), at any time during their hospital admission after birth. We included zinc supplementation in any formulation, regimen, or dose administered via the enteral route. We excluded infants who underwent gastrointestinal (GI) surgery during their initial hospital stay, or had a GI malformation or another condition accompanied by abnormal losses of GI juices, which contain high levels of zinc (including, but not limited to, stomas, fistulas, and malabsorptive diarrhoea).

DATA COLLECTION AND ANALYSIS

We used the standard methods of Cochrane Neonatal. Two review authors separately screened abstracts, evaluated trial quality and extracted data. We synthesised effect estimates using risk ratios (RR), risk differences (RD), and standardised mean differences (SMD). Our primary outcomes of interest were all-cause mortality and neurodevelopmental disability. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We included five trials with a total of 482 preterm infants; there was one ongoing trial. The five included trials were generally small, but of good methodological quality. Enteral zinc supplementation compared to no zinc supplementation Enteral zinc supplementation started in hospitalised preterm infants may decrease all-cause mortality (between start of intervention and end of follow-up period) (RR 0.55, 95% CI 0.31 to 0.97; 3 studies, 345 infants; low-certainty evidence). No data were available on long-term neurodevelopmental outcomes at 18 to 24 months of (post-term) age. Enteral zinc supplementation may have little or no effect on common morbidities such as bronchopulmonary dysplasia (RR 0.66, 95% CI 0.31 to 1.40, 1 study, 193 infants; low-certainty evidence), retinopathy of prematurity (RR 0.14, 95% CI 0.01 to 2.70, 1 study, 193 infants; low-certainty evidence), bacterial sepsis (RR 1.11, 95% CI 0.60 to 2.04, 2 studies, 293 infants; moderate-certainty evidence), or necrotising enterocolitis (RR 0.08, 95% CI 0.00 to 1.33, 1 study, 193 infants; low-certainty evidence). The intervention probably improves weight gain (SMD 0.46, 95% CI 0.28 to 0.64; 5 studies, 481 infants; moderate-certainty evidence); and may slightly improve linear growth (SMD 0.75, 95% CI 0.36 to 1.14, 3 studies, 289 infants; low-certainty evidence), but may have little or no effect on head growth (SMD 0.21, 95% CI -0.02 to 0.44, 3 studies, 289 infants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Enteral supplementation of zinc in preterm infants compared to no supplementation or placebo may moderately decrease mortality and probably improve short-term weight gain and linear growth, but may have little or no effect on common morbidities of prematurity. There are no data to assess the effect of zinc supplementation on long-term neurodevelopment.

Zinc supplementation for the promotion of growth and prevention of infections in infants less than six months of age

BACKGROUND

Zinc is a vital micronutrient for humans and is essential for protein synthesis, cell growth, and differentiation. Severe zinc deficiency can lead to slower physical, cognitive and sexual growth, cause skin disorders, decrease immunity, increase incidence of acute illnesses in infants and children and contribute to childhood stunting. By estimation, 17.3% of the world population is at risk of inadequate zinc intake. Such nutritional impairment increases the risk of diarrhoea and pneumonia by 20%, as well as leads to a global loss of more than 16 million disability-adjusted life years in children less than five years of age. Not only does zinc deficiency affect lives, it adds to the considerable financial burden on depleted resources in countries that are most affected. By preventing or curing this deficiency, we can improve childhood mortality, morbidity and growth.

OBJECTIVES

To assess the effectiveness of zinc supplementation for the promotion of growth, reduction in mortality, and the prevention of infections in infants less than six months of age.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2018, Issue 4), MEDLINE via PubMed (1966 to 18 May 2018), Embase (1980 to 18 May 2018), and CINAHL (1982 to 18 May 2018). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. An updated search from 1 January 2018 to 29 January 2020 was run in the following databases: CENTRAL via CRS Web, MEDLINE via Ovid, and CINAHL via EBSCOhost.

SELECTION CRITERIA

All randomised controlled (individual and cluster randomised) and quasi-randomised trials of zinc supplementation in healthy, term infants, less than six months of age comparing infant mortality, incidence of diarrhoea or respiratory illnesses, growth and/or serum zinc levels were eligible.

DATA COLLECTION AND ANALYSIS

Two review authors screened search results (title and abstracts) and relevant full texts. Studies fulfilling prespecified inclusion criteria were included with any disagreements resolved by consensus. Extraction and analysis were then conducted. We used the GRADE approach to assess the quality of evidence as indicated by certainty in effect estimates.

MAIN RESULTS

Eight studies (with 85,629 infants) were included and five studies were meta-analysed, out of which four studies compared zinc with placebo, and one compared zinc plus riboflavin versus riboflavin. Certain growth outcomes after six months of intervention (Weight for Age Z-scores (WAZ) (standardised mean difference) (SMD) 0.16, 95% CI 0.03 to 0.29; three studies, n = 955; fixed-effect; heterogeneity Chi² P = 0.96); I² = 0%); change in WAZ (SMD 0.16, 95% CI 0.07 to 0.25; one study, n = 386; fixed-effect); (Weight-for-Length Z-score (WLZ) (SMD 0.15, 95% CI 0.02 to 0.28; three studies, n = 955; fixed-effect; heterogeneity: Chi² P = 0.81); I² = 0%); (change in WLZ (SMD 0.17, 95% CI 0.06 to 0.28; one study, n = 386; fixed-effect)) were positively affected by zinc supplementation compared to placebo. A single study reported no difference in the incidence of diarrhoea and lower respiratory tract infection with zinc supplementation. Zinc had no effect on mortality in children younger than 12 months. When zinc plus riboflavin was compared to riboflavin only, significant improvement was observed in the incidence of wasting at 24 months (risk ratio (RR) 0.59, 95% CI 0.37 to 0.96; one study, n = 296; fixed-effect), but significant worsening of incidence of stunting was present at 21 months (RR 1.53, 95% CI 1.09 to 2.16; one study, n = 298; fixed-effect).

AUTHORS' CONCLUSIONS

There was a significant positive impact of zinc supplementation on WAZ and WLZ after six months of intervention in infants compared to placebo. When a combined supplement of zinc and riboflavin was compared to riboflavin, there was a significant reduction in wasting at 24 months, but stunting at 21 months was negatively affected. Although included trials were of good-to-moderate quality, evidence that could be meta-analysed was based on a few studies which affected the overall quality of results. Regardless, there is a need for strong trials conducted in infants younger than six months before a strong recommendation can be made supporting zinc supplementation in this age group.

Early Zinc Supplementation and Enhanced Growth of the Low-Birth Weight Neonate

BACKGROUND:

Nutritional deficits are almost universal in Low-Birth Weight babies. Zinc is essential for normal infant growth and its supplementation assists growth probably through insulin-like growth factor-1.

AIM:

This double-blind randomized-controlled trial aimed at evaluating the role of zinc in catch-up growth of low-birth-weight infants and investigating its proposed mediator.

MATERIAL AND METHODS:

The study was conducted in Ain Shams University Maternity Hospital. Two hundred low-birth-weight neonates were simply randomized to either oral zinc therapy or placebo. Anthropometric measurements were recorded at birth, 3, 6, and 12 months; including weight, recumbent length, head, waist, chest, and mid-upper arm circumferences, and triceps and sub-scapular skin fold thickness.

RESULTS:

We found that initial and 3-months measurements, except weight, were comparable in the 2 groups. All measurements at 6- and 12-months, except sub-scapular skin-fold-thickness, were significantly higher in zinc group than placebo. Catch-up growth, at 12-months, was significant in zinc group and was significantly higher in appropriate-for-gestational-age vs. small-for-gestational-age, in preterm vs. term, and in male vs. female infants. The median 6-months insulin-like growth factor-1 levels were significantly higher in zinc group.

CONCLUSION:

We conclude that early start of oral zinc supplementation in low-birth-weight neonates assists catch-up growth, probably through rise of insulin-like growth factor-1.