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

Amino acids and protein for preterm infants: How much and for what?

Protein and amino acids derived from protein digestion in the gastrointestinal tract or from intravenous infusions are fundamental for normal metabolism, growth, and neurodevelopmental outcomes in the fetus and the preterm infant of the same gestational age. Many studies support that at least 3.0-3.5 g/kg/day of protein or amino acids are needed to achieve normal nitrogen/protein balance and growth rates and the large fractional increase of lean mass in later gestation, either in the fetus or the preterm infant; this relationship is direct and linear. Faster growth rates in earlier gestation require more amino acids and protein than the late preterm or term infant. Protein synthesis and accretion also require sufficient energy, but above ∼120 kcal/kg/day, energy is largely diverted to fat production but not lean mass growth. Optimal IV amino acid solutions remain to be developed, and mature maternal milk and donor human milk require protein supplements to achieve appropriate protein balance and growth. Additional supplements of growth factors might augment increased protein intakes and fortifiers. While excess amino acid and/or protein intakes do not promote growth or development and might even be harmful, providing less than the amounts required guarantees poorer outcomes and should be avoided.

Improved linear growth after routine zinc supplementation in preterm very low birth weight infants

BACKGROUND

This study was designed (1) to compare growth, morbidity and mortality in < 33-week gestational age (GA) (very preterm, VPT) or very low birth weight (BW < 1500 grams, VLBW) infants before (Epoch-1) and after implementing routine enteral zinc (Zn) supplementation (Epoch-2) to meet recommendations, and (2) to assess serum Zn levels and associated variables.

METHODS

Single-center prospective cohort of 826 infants. The primary outcome was the change (Δ) in Z-scores of accurate length (Δlengthz), weight and head circumference from birth to discharge home.

RESULTS

In Epoch-2 vs Epoch-1 Δlengthz adjusted for confounding variables increased by 0.27 [95% confidence interval (CI) 0.13, 0.42, P < 0.001]. However, morbidity and mortality did not change. In Epoch-2 Zn decreased with GA and postnatal age: low ( < 0.74 mcg/mL) levels were observed in 51% infants. Retinopathy of prematurity (ROP) was independently associated with the lowest Zn [adjusted odds ratio 0.042 (CI 0.006, 0.306), area under the curve=0.928].

CONCLUSION

Routine enteral Zn supplementation was independently associated with improved linear growth but did not prevent occurrence of low Zn. ROP was independently associated with the lowest Zn.

IMPLICATIONS

Multicenter studies are needed to assess whether dosage of enteral Zn should be increased and whether Zn could help prevent ROP.

IMPACT

Implementation of routine enteral zinc (Zn) supplementation was associated with improved linear growth from birth to discharge and a more frequent physiologic growth curve in preterm very low birth weight infants. Serum Zn levels decreased with gestational age and with postnatal age. Low serum Zn levels were observed frequently despite routine Zn supplementation as currently recommended, which suggests a need to re-evaluate current enteral zinc supplementation guidelines for this population. Retinopathy of prematurity among infants < 33 weeks' gestation was independently associated with low gestational age, low birthweight, stage of bronchopulmonary dysplasia and the lowest serum Zn level.

Associations of Maternal Prenatal Zinc Consumption with Infant Brain Tissue Organization and Neurodevelopmental Outcomes

BACKGROUND/OBJECTIVES

While studies in rat pups suggest that early zinc exposure is critical for optimal brain structure and function, associations of prenatal zinc intake with measures of brain development in infants are unknown. This study aimed to assess the associations of maternal zinc intake during pregnancy with MRI measures of brain tissue microstructure and neurodevelopmental outcomes, as well as to determine whether MRI measures of the brain mediated the relationship between maternal zinc intake and neurodevelopmental indices.

METHODS

Forty-one adolescent mothers were recruited for a longitudinal study during pregnancy. Maternal zinc intake was assessed during the third trimester of pregnancy using a 24 h dietary recall. Infant MRI scans were acquired at 3 weeks postpartum using a 3.0 Tesla scanner to measure fractional anisotropy (FA) and mean diffusivity (MD). Cognitive, language, and motor skills were assessed at 4, 14, and 24 months postpartum using the Bayley Scales of Infant Development.

RESULTS

Greater prenatal zinc intake was associated with reduced FA in cortical gray matter, particularly in the frontal lobe [medial superior frontal gyrus; β (95% CI) = -1.0 (-1.5, -0.5)], in developing white matter, and in subcortical gray matter nuclei. Greater prenatal zinc intake was associated with reduced MD in cortical gray matter and developing white matter [superior longitudinal fasciculus; -4.4 (-7.1, -1.7)]. Greater maternal zinc intake also was associated with higher cognitive development scores at 14 [0.1 (0.0, 0.1)] and 24 [0.1 (0.0, 0.2)] months of age; MRI indices of FA and MD did not mediate this relationship.

CONCLUSIONS

Maternal prenatal zinc intake was associated with more favorable measures of brain tissue microstructural maturation and cognitive development during infancy.

Tracing Zinc's Role in Preterm Infants' Health: A Narrative Review

Zinc (Zn) is a trace element involved in numerous physiological processes, including enzyme function, gene transcription, and cell signaling. Its importance is especially pronounced in preterm infants, who are at high risk of Zn deficiency due to disrupted transplacental transfer, high nutrient demands, and medical complications. The inherent risk of Zn deficiency in this population is further increased by poor Zn dietary intake. Human milk from preterm mothers contains low concentrations of Zn, although it is highly bioavailable. Additionally, the Zn content steadily declines from colostrum (first few days postpartum) to mature milk (>10-14 d postpartum). Formula milk contains higher Zn concentrations to compensate for nutrient losses during production and storage, and lower bioavailability compared with human milk, which is further decreased in case of high phytate content, such as in soy milk-based formulas. Zn supplements may prove useful in meeting the preterm infant's needs, although caution is warranted regarding potential interactions with other nutrients within multinutrient supplements. Early detection of Zn deficiency is challenging due to the lack of reliable Zn status biomarkers, necessitating a high index of suspicion. Clinical signs of Zn deficiency can range from mild, nonspecific symptoms to severe, multisystem involvement. Chronic deficiency may lead to failure to thrive. Zn supplementation can support growth and mitigate comorbidities in preterm infants, although variability across studies complicates efforts to establish optimal dosing, and define safety and long-term effects. Although rare, Zn toxicity in preterm infants should not be overlooked, especially in infants on long-term parenteral nutrition. This narrative review aimed to consolidate existing knowledge and identify research gaps, highlighting the critical role of Zn in supporting preterm infants' health. Further research is needed to establish evidence-based practices to improve health outcomes in this vulnerable population.

Association of whole blood essential metals with neurodevelopment among preschool children

BACKGROUND

Essential metals may play roles in neurodevelopment. The aim was to evaluate the associations of magnesium (Mg), iron (Fe), copper (Cu), and zinc (Zn) levels with neurodevelopment among preschool children.

METHODS

The medical records of eligible children enrolled between January 2019 and July 2022 were retrospectively reviewed for required information. The quantitative measurement of metals was conducted using atomic absorption spectroscopy, while screening of neurodevelopment was performed using the Ages and Stages Questionnaire. Modified Poisson regression and Bayesian kernel machine regression (BKMR) analyses were used to evaluate the prevalence ratio (PR) of their independent and joint associations.

RESULTS

662 (14.8%) children were found to have possible neurodevelopmental delays. Modified Poisson regression showed that Mg, Cu, and Zn levels were independently and negatively associated with the risk of neurodevelopmental delay. The PRs (95% CIs) for per log2 increment of the above metals were 0.35 (0.19-0.62), 0.57 (0.42-0.77), and 0.63 (0.42-0.96). These negative associations were more pronounced in the gross motor and personal-social domains while considering the concrete five domains. BKMR showed a negative association of metal mixture with the risk of neurodevelopmental delay.

CONCLUSION

Mg, Cu, and Zn were inversely associated with neurodevelopmental delay. Sufficient essential metal levels are important for neurodevelopment.

IMPACT

Essential metals play a key role in neurodevelopment. The association of essential metal mixture with neurodevelopment is relatively scarce. Preschool children with possible neurodevelopmental delay are found to have lower Mg, Cu, and Zn levels than their counterparts. Single Mg, Cu, Zn levels, and elevated essential metal mixture are negatively associated with the risk of possible neurodevelopmental delay.

Potential Micronutrient Deficiencies in the First 1000 Days of Life: The Pediatrician on the Side of the Weakest

PURPOSE OF REVIEW

This study is to examine potential micronutrient deficiencies and any need for supplementation in children following specific diet plans in the first 1000 days of life.

RECENT FINDINGS

Optimal nutrition in the first 1000 days of life has a lifelong positive impact on child development. Specific intrauterine and perinatal factors, pathological conditions, and dietary restrictions can represent potential risk factors for micronutrient deficiencies in the first 1000 days of life, which can have negative systemic consequences. Preterm and low-birth-weight infants are intrinsically at risk because of immature body systems. Children affected by cystic fibrosis are prone to malnutrition because of intestinal malabsorption. The risk of micronutrient deficiency can increase in various situations, including but not limited to children following selective dietary regimens (vegetarian and vegan diets and children affected by specific neuropsychiatric conditions) or specific dietary therapies (children affected by food allergies or specific metabolic disorders and children following restricted diet as a part of therapeutic approach, i.e., ketogenic diet for epilepsy). In light of this situation, the micronutrient status in these categories of children should be investigated in order to tailor strategies specific to the individual's metabolic needs, with a particular focus on deficiencies which can impair or delay the physical and cognitive development of children, namely, vitamin B12, vitamin D and folic acid, as well as oligo-elements such as iron, zinc, calcium, sodium, magnesium, and phosphorus, and essential fatty acids such as omega-3. Identification of micronutrient deficiency in the first 1000 days of life and timely supplementation proves essential to prevent their long-term consequences.

Effect of Enteral Zinc Supplementation on the Anthropometric Measurements of Preterm Infants at Discharge from the Neonatal Intensive Care Unit and Evaluation of Copper Deficiency

Enteral zinc supplementation in preterm infants has been reported to improve short-term weight and height gain. This study aims to evaluate whether early enteral zinc supplementation in preterm infants admitted to the neonatal intensive care unit (NICU) affects their physical measurements at discharge, and to periodically test serum copper levels. Of the 221 patients admitted to the NICU, 102 were in the zinc group and 119 were in the no-zinc group. The zinc group was administered 3 mg/kg/day of zinc. Body weight, height, and head circumference at discharge (or on the expected delivery date) were evaluated, and the factors affecting these parameters were examined. Serum zinc and copper levels were also evaluated on admission and monthly thereafter. Multivariate analysis was performed and showed that the weeks of gestational age and small for gestational age (SGA) status affected the height and weight at discharge. SGA also affected the head circumference. Serum copper levels were within the reference range for all patients at 3 months of age. Enteral zinc supplementation of 3 mg/kg/day in preterm infants did not affect the weight, height, or head circumference at discharge, but was shown to be relatively safe.

Use of dietary supplements by children and adolescents

OBJECTIVES

Narrative review evaluating the use of dietary supplements by children and adolescents.

DATA SOURCE

The terms "dietary supplements", "children" and "adolescents" were used in combination in the PubMed, MEDLINE, and SciELO databases, between 2000 and 2023, evaluating studies in humans, published in Portuguese, English, French and Spanish.

DATA SYNTHESIS

The use of dietary supplements by children and adolescents has increased in recent decades. The most commonly used supplements are vitamins, minerals, trace elements, proteins, amino acids, melatonin, fatty acids, probiotics and energy drinks.

CONCLUSION

Despite having specific indications, most of the time they are not prescribed by a healthcare professional. The reasons for use are varied. In children, the main reasons are protection against infections, stimulating growth, and poor food intake, with multivitamins and minerals being the most commonly used supplements. In adolescents, they are used to improve athletic performance and attain the "ideal body", with proteins and amino acids being the most often used nutrients. As they are not regulated by health agencies and are sold without a prescription, their unsupervised use can lead to inadequate doses, with inefficiency or overdose risk. As for compounding formulations, or when available in preparations with multiple nutrients, the chance of errors increases. It is essential that pediatricians advise parents and patients about the indications, risks and benefits, prescribing them when necessary.

Growth after implementing a donor breast milk program in neonates <33 weeks gestational age or birthweight <1500 grams: Retrospective cohort study

BACKGROUND

Donor breast milk (DBM) feeding has been associated with less growth than formula in preterm infants. Zinc content in DBM is insufficient to support growth in preterm infants.

OBJECTIVE

To compare growth from birth to discharge, macro- and micronutrient intake and the frequency of poor growth before (Epoch-1) and after (Epoch-2) implementing a DBM program.

METHODS

Retrospective cohort study of 1069 infants born at < 33 weeks' gestational age or birthweight < 1500 g and fed using our adjustable feeding protocol with accurate serial length measurements. Growth was assessed by changes in Z-scores of weight, length and fronto-occipital circumference from birth to discharge.

RESULTS

Growth did not decrease significantly in Epoch-2. However, energy and protein intake increased by 5% and frequency of zinc and vitamin D supplementation increased by >30%.

CONCLUSIONS

DBM implementation did not significantly decrease growth from birth to discharge using our adjustable feeding protocol.

Enteral Nutrition in Preterm Infants (2022): A Position Paper From the ESPGHAN Committee on Nutrition and Invited Experts

OBJECTIVES

To review the current literature and develop consensus conclusions and recommendations on nutrient intakes and nutritional practice in preterm infants with birthweight <1800 g.

METHODS

The European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) Committee of Nutrition (CoN) led a process that included CoN members and invited experts. Invited experts with specific expertise were chosen to represent as broad a geographical spread as possible. A list of topics was developed, and individual leads were assigned to topics along with other members, who reviewed the current literature. A single face-to-face meeting was held in February 2020. Provisional conclusions and recommendations were developed between 2020 and 2021, and these were voted on electronically by all members of the working group between 2021 and 2022. Where >90% consensus was not achieved, online discussion meetings were held, along with further voting until agreement was reached.

RESULTS

In general, there is a lack of strong evidence for most nutrients and topics. The summary paper is supported by additional supplementary digital content that provide a fuller explanation of the literature and relevant physiology: introduction and overview; human milk reference data; intakes of water, protein, energy, lipid, carbohydrate, electrolytes, minerals, trace elements, water soluble vitamins, and fat soluble vitamins; feeding mode including mineral enteral feeding, feed advancement, management of gastric residuals, gastric tube placement and bolus or continuous feeding; growth; breastmilk buccal colostrum, donor human milk, and risks of cytomegalovirus infection; hydrolyzed protein and osmolality; supplemental bionutrients; and use of breastmilk fortifier.

CONCLUSIONS

We provide updated ESPGHAN CoN consensus-based conclusions and recommendations on nutrient intakes and nutritional management for preterm infants.

Associations between Elemental Metabolic Dynamics and Default Mode Network Functional Connectivity Are Altered in Autism

Autism is a neurodevelopmental condition associated with atypical social communication, cognitive, and sensory faculties. Recent advances in exposure biology suggest that biomarkers of elemental uptake and metabolism measured in hair samples can yield an effective signal predictive of autism diagnosis. Here, we investigated if elemental biomarkers in hair were associated with functional connectivity in regions of the default mode network (DMN) previously linked to autism. In a study sample which included twin pairs with concordant and discordant diagnoses for autism, our analysis of hair samples and neuroimaging data supported two general findings. First, independent of autism diagnosis, we found a broad pattern of association between elemental biomarkers and functional connectivity in the DMN, which primarily involved dynamics in zinc metabolism. Second, we found that associations between the DMN and elemental biomarkers, particularly involving phosphorus, calcium, manganese, and magnesium, differed significantly in autistic participants from control participants. In sum, these findings suggest that functional dynamics in elemental metabolism relate broadly to persistent patterns of functional connectivity in the DMN, and that these associations are altered in the emergence of autism.