Exchangeable zinc pool size at birth is smaller in small-for-gestational-age than in appropriate-for-gestational-age preterm infants

Transient Symptomatic Zinc Deficiency in a Breastfed Infant Associated with Low Zinc Levels in Maternal Serum and Breast Milk Improving after Zinc Supplementation: An Uncommon Phenotype?

Acrodermatitis enteropathica (AE) is a rare, autosomal-recessive disorder of neonatal zinc deficiency due to SLC39A4 (intestinal zinc transporter, Zip4) gene mutation with onset after weaning while breastfeeding during this period will be protective. Transient symptomatic zinc deficiency is also acquired rarely in breastfed infants with increased zinc requirements and/or inadequate concentration of zinc in breast milk. The nursing mothers of transient symptomatic zinc deficiency infants show SLC30A2 (mammary epithelial zinc transporter, ZnT-2) gene mutation and abnormally low zinc levels in the breast milk despite normal serum zinc levels, which do not improve after zinc supplementation. A 2-month-old breastfed male infant had AE-like clinical features of zinc deficiency for two weeks. His symptoms and low serum zinc levels improved rapidly after zinc supplementation. The mother also had low serum and breast milk zinc concentration and both improved after oral zinc therapy indicating a non-heritable phenotype. The relevant literature is reviewed and significance of dietary zinc supplementation during pregnancy/lactation is emphasized.

Exchangeable Zinc Pool Size at Birth in Pakistani Small for Gestational Age and Appropriate for Gestational Age Infants Do Not Differ But Are Lower Than in US Infants

OBJECTIVES

Small for gestational age (SGA) infants are more susceptible to infectious morbidity and growth faltering compared to their appropriate for gestational age (AGA) counterparts. Zinc supplementation of SGA infants may be beneficial but the underlying susceptibility to zinc deficiency of SGA infants has not been examined.

METHODS

In a community-based, observational, longitudinal study in a peri-urban settlement of Karachi, Pakistan, we compared the size of the exchangeable zinc pools (EZPs) in term SGA and AGA infants at birth and at 6 months of age, hypothesizing that the EZP would be lower in the SGA group. To measure EZP size, a zinc stable isotope was intravenously administered within 48 hours of birth (n = 17 and 22) at 6 months (n = 11 and 14) in SGA and AGA infants, respectively. Isotopic enrichment in urine was used to determine EZP.

RESULTS

No significant difference was detected in the mean (±standard deviation) EZP between SGA and AGA infants at birth, with values of 9.8 ± 3.5 and 10.1 ± 4.1 mg/kg, respectively (P = 0.86), or at 6 months. Longitudinal EZP measurements demonstrated a significant decline in EZP relative to body weight in both groups at 6 months (P < 0.001). Mean EZP (adjusted for body weight) size at birth for the combined Pakistani groups was significantly lower than AGA infants at birth in the United States (P = 0.017).

CONCLUSIONS

These results did not support a difference in zinc endowment between SGA and AGA Pakistani infants. They, however, do suggest lower in utero zinc transfer to the fetus in a setting where poor maternal nutritional status may confer a high susceptibility to postnatal zinc deficiency.

Zinc deficiency in infants and children: a review of its complex and synergistic interactions

Zinc deficiency is estimated to contribute to over half a million deaths per year in infants and children under 5 years of age. This paper reviews the features of mild-to-moderate zinc deficiency, which include growth faltering, deficits in immune function and altered integrity and function of the gastro-intestinal tract. Sub-clinical features include oxidative stress and a pro-inflammatory state. The homeostatic response to low dietary zinc intake by increasing absorption is limited, especially if the source of zinc is of poor bioavailability, and conservation of endogenous intestinal losses is a critical component of adaptation. Owing to low zinc intakes, older breastfed infants, especially those of low birthweight, are predictably at risk of zinc deficiency if complementary food choices are unfortified and/or low in zinc. Host factors such as young age, poor intra-uterine zinc accretion owing to poor maternal status and/or prematurity, and gastro-intestinal dysfunction also potently predispose to zinc deficiency. Environmental enteropathy, which is prevalent in low-resource settings, may substantially impair zinc absorption and/or increase endogenous losses, and thus lead to relatively high zinc requirements. Emerging evidence highlights common features between chronic inflammation and zinc deficiency, and each may exacerbate the other. More investigations of zinc homeostasis in populations in low-resource settings are needed to better quantify absorption capacity and losses. Effective preventive strategies must address potentially higher zinc requirements as well as the underlying context that perpetuates a vicious cycle of zinc deficiency and multiple adverse outcomes.

Breast milk zinc transfer and early post-natal growth among urban South Indian term infants using measures of breast milk volume and breast milk zinc concentrations

Zinc (Zn) deficiency in infancy and early childhood is of public health concern in developing countries. This study aimed to longitudinally assess Zn intake of urban South Indian term infants in the first 6 months of life using measures of breast milk (BM) volume and BM Zn concentrations and, additionally, to study the effect of BM Zn intake on infant length and weight gain. BM intake by the deuterium dilution technique, BM Zn concentration at months 1, 3 and 6, as well as serum Zn level at months 3 and 6 were assessed in 50 mother-infant pairs. BM intake significantly declined from 627 mL day(-1) at month 1 to 608 mL day(-1) at month 6 (P < 0.01). BM Zn concentration and intake significantly declined from month 1 to month 6 (P < 0.001 for both). Mean infant serum Zn level at months 3 and 6 were 93.0 ± 27.1 and 99.6 ± 30.1 µg dL(-1), respectively. Infant BM Zn intake at months 1 and 3 was not associated with the weight and length gain between 1-3 and 3-6 months, respectively. Zn intake from BM, maternal BM Zn content and serum Zn levels were not significantly different between small-for-gestational age and appropriate-for-gestational age infants. Therefore, among urban south Indian term infants less than 6 months of age, BM Zn intakes were low, owing to low volumes of BM intake, despite BM Zn concentrations being in the normal range. Promotion of breastfeeding and thereby increasing the volumes of milk produced is a first important step towards improving Zn intake among infants.

Effect of zinc supplementation on growth in very low birth weight infants

This was a randomized blinded placebo controlled trial undertaken to study the role of zinc supplementation on growth, primarily the linear growth velocity in very low birth weight (VLBW) infants at 3 months corrected age (CA). Out of 134 neonates with birth weight <1500 g, 101 babies were eligible. Due to lack of consent 10 were excluded. The remaining 91 neonates who were comparable for sex, gestational age, birth weight, APGAR and age at enrollment were randomized to receive either 1 ml of zinc sulfate (10 mg elemental zinc) (n = 46) or 1 ml placebo (n = 45) from enrollment to 60 days. The infants in the zinc group had significantly higher linear growth velocity (0.98 ± 0.12 cm week(-1)) compared to a placebo group (0.67 ± 0.15 cm week(-1)) (p < 0.001) at 3 months CA. We concluded that zinc supplementation at 10 mg day(-1) for 60 days in VLBW infants improves their linear growth during infancy.

Zinc absorption and zinc status are reduced after Roux-en-Y gastric bypass: a randomized study using 2 supplements

BACKGROUND

Micronutrient deficiencies are common in patients undergoing gastric bypass. The effect of this type of surgery on zinc absorption and zinc status is not well known.

OBJECTIVE

The objective was to evaluate the effects of Roux-en-Y gastric bypass (RYGBP) on zinc status and zinc absorption at different stages after surgery. We hypothesized that zinc status would be significantly impaired after surgery and that this impairment would be less severe in subjects receiving increased supplemental zinc. We also hypothesized that zinc absorption would be lower after surgery.

DESIGN

Anthropometric and body-composition variables and dietary and biochemical indexes of zinc status and zinc absorption were determined in 67 severe and morbidly obese women [mean (±SD) age: 36.9 ± 9.8 y; BMI (in kg/m(2)): 45.2 ± 4.7] who underwent RYGBP. The subjects were randomly assigned to 1 of 2 vitamin-mineral supplementation groups. Measurements were made before and 6, 12, and 18 mo after surgery. Fifty-six subjects completed the 18-mo follow-up.

RESULTS

Mean plasma zinc, erythrocyte membrane alkaline phosphatase activity, and the size of the rapidly exchangeable zinc pool decreased after RYGBP. Percentage zinc absorption decreased significantly from 32.3% to 13.6% at 6 mo after RYGBP and to 21% at 18 mo after surgery. No effect of supplement type was observed.

CONCLUSIONS

Zinc status is impaired after RYGBP, despite the finding that dietary plus supplemental zinc doubled recommended zinc intakes in healthy persons. Zinc absorption capacity is significantly reduced soon after RYGBP, with no major changes until 18 mo after surgery.

Trace element status and inflammation parameters after 6 months of Roux-en-Y gastric bypass

BACKGROUND

Knowledge about the practical consequences of the nutritional status of Fe, Zn, and Cu and inflammation in obesity is limited. The objective of this study was to evaluate changes on trace element status and their potential associations with selected inflammation parameters in patients after Roux-en-Y gastric bypass (RYGBP).

METHODS

Sixty-three women (mean age, 36.9 ± 9.2 years, body mass index, 43.8 ± 4.3 kg/m²) were evaluated at baseline and 6 months after RYGBP. Anthropometric (weight, waist circumference), body composition (fat mass and fat-free mass), dietary (nutrient intakes), and metabolic and inflammation (glucose, insulin, HOMA-IR, adiponectin, HDL-cholesterol, LDL-cholesterol, triglycerides, hs-CRP, leukocytes, polymorphonuclear neutrophils (PMN)) parameters were determined in addition to selected indices of Fe, Zn, and Cu status.

RESULTS

All but one (HDL-cholesterol) metabolic and inflammation parameters had significant differences when compared before and after RYGBP. Hemoglobin, serum ferritin, the size of the rapidly exchangeable zinc pool, and plasma copper decreased after RYGBP. Plasma and hair zinc, as well as zinc protoporphyrin increased. The change in Hb was significantly associated (p < 0.05) to the change in leukocytes (r = 0.33) and adiponectin (r = -0.44). Zinc protoporphyrin change was associated to the change in PMN (r = 0.32) and HDL-cholesterol (r = -0.29). No other associations between the changes of the rest of Fe, Zn, and Cu parameters with the changes of any of the metabolic and inflammation parameters were observed.

CONCLUSION

RYGBP produced significant weight and fat mass losses, with improvement of metabolic and inflammation parameters. Iron, zinc, and copper status were impaired after the surgery.

Preterm infants with chronic lung disease: are protein and energy intakes after discharge sufficient for optimal growth?

AIM

To document post-discharge feeding practices of preterm infants with chronic lung disease (CLD) and determine if sufficient protein and energy is consumed for optimal growth.

METHOD

Protein and energy intakes of preterm infants with CLD were quantified through detailed analysis of measured food and fluid intakes at four corrected age (CA) assessments, post-discharge. Most of the infants were in hospital for the term assessment. Milk intake from breastfeeding was determined by test weighing. Protein and energy intakes were compared with the Australian and New Zealand Nutrient Reference Values (NRV) for healthy term-born infants, and CA z-scores for weight, length and head circumference were calculated using Australian national gestational growth data and Centre for Disease Control 2000 growth data.

RESULTS

Ten of the 28 CLD infants who were exclusively receiving expressed breast milk in hospital were transitioned to infant formula within 1 month of discharge. Complementary foods were introduced at a median CA of 3.6 months. Protein intakes almost always exceeded the NRV for healthy term-born infants, and at each assessment, at least 63% of infants met the energy NRV. Longitudinal growth data are available for 20 infants, four of whom had been small for gestational age. At the 12-month assessment, 10 of these infants weighed less than the 10th percentile.

CONCLUSION

Preterm infants who develop CLD do not always achieve reference growth in their first year following discharge, despite protein and energy intakes being mostly comparable to those recommended for healthy term-born infants.

Symptomatic acquired zinc deficiency in at-risk premature infants: high dose preventive supplementation is necessary

Zinc is a cofactor for several enzymes involved in many metabolisms. Zinc deficiency induces various disorders such as acrodermatitis enteropathica, either inherited or acquired. We report three cases of premature infants (24-31 wks gestational age) with low birthweight (650 to 940 g) and enteropathy, two of whom presented with necrotizing enterocolitis. All infants were fed by total parenteral nutrition. At a chronological age ranging from 73 to 80 days, all infants developed a periorificial dermatitis. Before the onset of the first signs, they had received zinc supplementation ranging from 146% to 195% of the recommended dose (400 microg/kg/day). Increased zinc supplementation over a course of 6-18 days induced a complete resolution of symptoms in all cases. No abnormality in the neurologic examination and no recurrence were observed at the end of the zinc treatment. Low birthweight premature infants with enteropathy on total parenteral nutrition are at risk of developing zinc deficiency. The usual recommended zinc supplementation is probably insufficient for those infants. A delay in the diagnosis of zinc deficiency may lead to severe complications.

Effect of zinc supplementation on morbidity and growth in hospital-born, low-birth-weight infants

BACKGROUND

Low-birth-weight infants may have impaired zinc status, but little is known about the effect of zinc supplementation.

OBJECTIVE

The objective was to investigate the effect of daily zinc supplementation on morbidity and anthropometric status in hospital-born, low-birth-weight infants.

DESIGN

In a double-blind, randomized, placebo-controlled trial, 2052 hospital-born term infants with a birth weight < or =2500 g were randomly assigned to receive zinc or placebo. The zinc group received elemental zinc: 5 mg/d for those infants between ages 2 wk and 6 mo and 10 mg/d for those infants aged >6 mo. All-cause hospitalizations, prevalence of diarrhea, acute lower respiratory tract infections, visits to health care providers, weights, and lengths were ascertained at 3, 6, 9, and 12 mo of age.

RESULTS

The supplement was consumed for >85% of the follow-up period. Mean plasma zinc at 12 mo of age was higher in the zinc group (100.2 microg/dL) than in the control group (73.3 microg/dL) (difference in means: 26.9; 95% CI: 19.6, 34.2). The 24-h and 7-d prevalence of diarrhea and acute lower respiratory tract infections was similar at 3, 6, 9, and 12 mo. Care-seeking for illness was significantly lower in the zinc group (difference in proportions: -5.7; 95% CI: -9.9, -1.4; P < 0.05) at 9 mo. The numbers of hospitalizations, weights, and lengths were all similar at all 4 assessments.

CONCLUSION

Hospital-born, term, low-birth-weight infants do not seem to benefit substantially from zinc supplementation that meets the Recommended Dietary Allowance for zinc in terms of morbidity or physical growth during infancy in this setting. This trial was registered at www.clinicaltrials.gov as NCT00272142.

Human placental IGF-I and IGF-II expression: correlating maternal and infant anthropometric variables and micronutrients at birth in the Pakistani population

AIM

To correlate infant birth weight with maternal and infant biometric data, including the expression of placental IGF-I and IGF-II at birth, and levels of serum zinc and ferritin.

METHODS

The data consisted of observations from 89 women from Karachi, Pakistan. Placental and cord blood samples were taken immediately following delivery and were subsequently divided into two groups, small and large for gestational age (SGA and LGA).

RESULTS

The mean birth weight was 2.79 kg; the prevalence of SGA being 13.4% (< or =10th percentile); the prevalence of LGA being 23.6% (> or =90th percentile). Placental IGF-I and IGF-II mRNA expression was greater in the LGA group (p < 0.05). Furthermore, a significant correlation was noted between infant birth weight and maternal anthropometric parameters (p < 0.01). Cord zinc levels were also significantly higher in the LGA group (p < 0.05).

CONCLUSION

Maternal anthropometry, along with placental IGF-I and IGF-II mRNA levels, correlated significantly with infant birth weight suggesting the importance of these growth factors for birth weight outcomes. The higher zinc levels in the LGA group also suggest the importance of this micronutrient in foetal growth. Our results suggest that growth problems have a multifactorial aetiology arising from within the infant rather than due to maternal constraint alone.

Zinc deficiency: a special challenge

In the development and testing of programs designed to improve complementary feeding globally, local nonfortified food-based solutions comprise an important strategy for the foreseeable future. These solutions are especially vital for the rural poor of less-developed countries. Zinc is notable among individual nutrients that have been designated as "problem" nutrients, adequate intake of which is difficult from complementary foods without fortification. This article considers the potential role of meat +/- liver in addressing this apparent problem. In a recent Colorado study, beef and cereal have been determined to be equally acceptable between age 5-7 mo as first and regular complementary foods. Average intake and absorption of Zn from beef by 7 mo of age, together with the modest intake/absorption of Zn from breast milk at that age, were adequate to meet average dietary and physiologic zinc requirements, respectively. Barriers to acceptability and availability of affordable meat are considered, but these are neither universal nor irresolvable in all populations.

Complementary feeding: clinically relevant factors affecting timing and composition

Exclusive breastfeeding for the first 6 mo of life followed by optimal complementary feeding are critical public health measures for reducing and preventing morbidity and mortality in young children. Clinical factors, such as birth weight, prematurity, and illness, that affect the iron and zinc requirements of younger infants are discussed. Maternal diet and nutritional status do not have a strong effect on the mineral content of human milk, but physiologic changes in milk and the infants' status determine the dependence of the infant on complementary foods in addition to human milk to meet iron and zinc requirements after 6 mo. The nature of zinc absorption, which is suitably characterized by saturation response modeling, dictates that plant-based diets, which are low in zinc, are associated with low absolute daily absorbed zinc, which is inadequate to meet requirements. Foods with a higher zinc content, such as meats, are much more likely to be sufficient to meet dietary requirements. Current plant-based complementary feeding patterns for older fully breastfed infants in both developed and developing countries pose a risk of zinc deficiency. The strong rationale for the potential benefits of providing meat as an early complementary food, and the examples of successful intervention programs, provide potent incentives to pursue broader implementation programs, with concurrent rigorous evaluation of both efficacy and effectiveness.

Food choices to meet nutritional needs of breast-fed infants and toddlers on mixed diets

The primary focus of this review is considerations for complementary feedings to meet micronutrient needs of infants aged 6-24 mo who are continuing with breast-feeding and minimal or no formula. The World Health Organization recommends initiation of complementary feeding to breast-fed infants at approximately 6 mo of age. Whether complementary foods will meet nutrient needs will depend on the types of food selected. One criterion for the selection of complementary foods is that they be rich sources of zinc and iron because both of these essential micronutrients are critical for normal growth and development, and requirements are not met by exclusive breast-feeding after approximately 6 mo. For an exclusively breast-fed 7-mo-old infant, human milk provides approximately 0.5 mg of zinc, and a little over half of that is absorbed. Adding some cereal can increase zinc intake modestly but will fall short of providing the estimated physiologic requirement because adaptive mechanisms are inadequate to compensate for moderately low zinc intake. Maize, wheat, rice, and roots are also relatively low in zinc and have the added factor of a high phytate-to-zinc molar ratio, which makes the zinc less bioavailable. Meats and liver have greater zinc and iron concentrations than unfortified plant foods and have been shown to have good acceptance by 7-mo-old infants. In contrast to current practices in both developed and developing countries, meats should be considered as an early complementary food for breast-fed infants to provide essential micronutrients.