Zinc deficiency in an exclusively breast-fed preterm infant

Zinc-Deficient Rats Have More Limited Bone Recovery During Repletion Than Diet-Restricted Rats

The objective of this study was to investigate the effects of dietary zinc deficiency and diet restriction on bone development in growing rats, and to determine whether any adverse effects could be reversed by dietary repletion. Weanling rats were fed either a zinc-deficient diet ad libitum (ZD; <1 mg zinc/kg) or nutritionally complete diet (30 mg zinc/kg) either ad libitum (CTL) or pair-fed to the intake of the ZD group (DR; diet-restricted) for 3 weeks (deficiency phase) and then all groups were fed the zincadequate diet ad libitum for 3, 7, or 23 days (repletion phase). Excised femurs were analyzed for bone mineral density (BMD) using dual-energy x-ray absorptiometry, and plasma was analyzed for markers of bone formation (osteocalcin) and resorption (Ratlaps). After the deficiency phase, ZD had lower body weight and reduced femur BMD, zinc, and phosphorus concentrations compared with DR; and these parameters were lower in DR compared with CTL. Femur calcium concentrations were unchanged among the groups. Reduced plasma osteocalcin in ZD and elevated plasma Ratlaps in DR suggested that zinc deficiency limits bone formation while diet restriction accelerates bone resorption activity. After 23 days of repletion, femur size, BMD, and zinc concentrations remained lower in ZD compared with DR and CTL. Body weight and femur phosphorus concentrations remained lower in both ZD and DR compared with CTL after repletion. There were no differences in plasma osteocalcin concentrations after the repletion phase, but the plasma Ratlaps concentrations remained elevated in DR compared with CTL. In summary, both ZD and DR lead to osteopenia during rapid growth, but the mechanisms appear to be due to reduced modeling in ZD and higher turnover in DR. Zinc deficiency was associated with a greater impairment in bone development than diet restriction, and both deficiencies limited bone recovery during repletion in growing rats.

Dietary Sources of Zinc and Factors Affecting its Bioavailability

Zinc is one of the more ubiquitous of nutrients, being found in modest amounts in a large number of foods. Human evolution has undoubtedly shaped the needs for zinc to be absorbed from our beverages and foods of both animal and plant origin in the diet. Different environmental and ecological circumstances modify the amount of zinc that needs to become available to individuals of different regions. We use an acronym approach to review and understand the bioavailability of zinc. The biological availability of zinc can be limited by many factors intrinsic and extrinsic to the host, and it can be enhanced by few. Challenges remain in assessing the bioavailability of zinc compounds as fortificants and in developing strategies to improve the uptake of the metal by reducing phytate and tannin content of diets, either through food technology or plant genetics.

Zinc and infant nutrition

Zinc is essential for a wide variety of cellular processes in all cells. It is a critical dietary nutrient, particularly in the early stages of life. In the early neonatal period, adequate sources of zinc can be obtained from breast milk. In rare circumstances, the mammary gland produces zinc deficient milk that is potentially lethal for exclusively breast-fed infants. This can be overcome by zinc supplementation to the infant. Alterations to key zinc transporters provide insights into the mechanisms of cellular zinc homeostasis. The bioavailability of zinc in food depends on the presence of constituents that may complex zinc. In many countries, zinc deficiency is a major health issue due to poor nourishment. Young children are particularly affected. Zinc deficiency can impair immune function and contributes to the global burden of infectious diseases including diarrhoea, pneumonia and malaria. Furthermore, zinc deficiency may extend its influence across generations by inducing epigenetic effects that alter the expression of genes. This review discusses the significance of adequate zinc nutrition in infants, factors that influence zinc nutrition, the consequences of zinc deficiency, including its contribution to the global burden of disease, and addresses some of the knowledge gaps in zinc biology.

Altered expression of two zinc transporters, SLC30A5 and SLC30A6, underlies a mammary gland disorder of reduced zinc secretion into milk

Two cases of zinc deficiency in breastfed neonates were investigated where zinc levels in the mothers' milk were reduced by more than 75 % compared to normal. The objective of this study was to find the molecular basis of the maternal zinc deficiency condition. Significant reductions in mRNA expression and protein levels of the zinc transporters SLC30A5 and SLC30A6 were found in maternal tissue, suggesting a causal link to the zinc-deficient milk. Novel splice variants of the SLC30A6 transcript were detected. No modifications were found in coding regions, or in transcription binding sites of promoter regions or in 5' and 3' untranslated regions of both transporters in lymphoblasts and fibroblasts isolated from both mothers. Altered DNA methylation in SLC30A5 at two CpG sites was detected and may account for the reduced levels of SLC30A5 mRNA and protein in lymphoblasts. Reduced SLC30A6 mRNA and protein levels in lymphoblasts may be secondary to reduced SLC30A5 expression, as they function as a heterodimer in zinc transport. In conclusion, two cases of zinc deficiency are linked to low levels of the SLC30A5 and SLC30A6 zinc transporters. These two zinc transporters have not been previously associated with zinc deficiency in milk.

Zinc: The Metal of Life

The importance of zinc was 1st reported for Aspergillus niger. It took over 75 y to realize that zinc is also an essential trace element for rats, and an additional 30 y went by before it was recognized that this was also true for humans. The adult body contains about 2 to 3 g of zinc. Zinc is found in organs, tissues, bones, fluids, and cells. It is essential for many physiological functions and plays a significant role in a number of enzyme actions in the living systems. Bioinformatics estimates report that 10% of the human proteome contains zinc-binding sites. Based on its role in such a plethora of cellular components, zinc has diverse biological functions from enzymatic catalysis to playing a crucial role in cellular neuronal systems. Thus, based on the various published studies and reports, it is pertinent to state that zinc is one of the most important essential trace metals in human nutrition and lifestyle. Its deficiency may severely affect the homeostasis of a biological system. This review compiles the role of zinc in prophylaxis/therapeutics and provides current information about its effect on living beings.

Effect of breastfeeding on serum zinc levels and growth in healthy infants

BACKGROUND

This study investigated the association among breastfeeding, serum zinc levels, and nutritional status of children.

SUBJECTS AND METHODS

One hundred healthy infants were included in the study. Anthropometric measurements of the children were taken, and their plasma zinc levels were determined. The mothers were interviewed about the duration of breastfeeding and nutrition pattern of the children at the time of zinc measurement.

RESULTS

Low zinc levels were associated with lower weight measurements (r=0.49, p<0.001), but the association between height and zinc level was not statistically significant (r=0.18, p>0.05). There was a negative correlation between breastfeeding duration and weight-for-age percentile (r=-0.2, p<0.05), height-for-age percentile (r=-0.3, p<0.05), and serum zinc level (r=-0.3, p=0.002). The pattern of nutrition correlated only with the weight of the infant (r=0.2, p<0.05) and not with either height or serum zinc levels (p>0.05).

CONCLUSIONS

Exclusive breastfeeding beyond 6 months of age has negative effects on serum zinc levels and can be associated with low weight gain, which will be especially important in developing countries.

Zinc deficiency and its inherited disorders -a review

Zinc is an essential trace element required by all living organisms because of its critical roles both as a structural component of proteins and as a cofactor in enzyme catalysis. The importance of zinc in human metabolism is illustrated by the effects of zinc deficiency, which include a diminished immune response, reduced healing and neurological disorders. Furthermore, nutritional zinc deficiency can be fatal in newborn or growing animals. While zinc deficiency is commonly caused by dietary factors, several inherited defects of zinc deficiency have been identified. Acrodermatitis enteropathica is the most commonly described inherited condition found in humans. In several of the few cases that have been reported, this disorder is associated with mutations in the hZIP4 gene, a member of the SLC39 family, whose members encode membranebound putative zinc transporters. Mutations in other members of this family or in different genes may account for other cases of acrodermatitis in which defects in hZIP4 have not been detected. Another inherited form of zinc deficiency occurs in the lethal milk mouse, where a mutation in ZnT4 gene, a member of the SLC30 family of transmembrane proteins results in impaired secretion of zinc into milk from the mammary gland. A similar disorder to the lethal milk mouse occurs in humans. In the few cases studied, no changes in ZnT4 orthologue, hZnT4, were detected. This, and the presence of several minor phenotypic differences between the zinc deficiency in humans and mice, suggests that the human condition is caused by defects in genes that are yet to be identified. Taking into account the fact that there are no definitive tests for zinc deficiency and that this disorder can go undiagnosed, plus the recent identification of multiple members of the SCL30 and SLC39, it is likely that mutations in other genes may underlie additional inherited disorders of zinc deficiency.

Zinc and copper concentrations in human preterm milk

Zinc and copper are important trace elements in the nutrition of preterm infants. This study determined and compared the concentrations of zinc and copper in preterm milk of mothers receiving and not receiving zinc supplementation diets. The effects of maternal supplementation on the blood levels and anthropometric parameters were evaluated. Thirty-eight mothers and their preterm infants were enrolled in the study. Eighteen mothers were given a daily supplementation of 50 mg zinc, whereas the other 20 were not. Zinc and copper levels in milk were determined at 15-day intervals, as were blood zinc levels along with anthropometric parameters. Zinc and copper contents were determined by atomic absorption spectrophotometry. No significant differences were found between groups either for zinc values in maternal milk and infant blood or for anthropometric measurements. A pronounced decrease in copper levels was observed in mothers receiving supplemental zinc. Zinc supplementation given to mothers who were breastfeeding preterm infants had no significant effect on zinc secretion in milk.

[Transient zinc deficiency in preterm infants]

Zinc is an essential element and necessary for various cellular functions. Preterm infants may have a negative zinc balance and are therefore especially susceptible for symptomatic zinc deficiency. We report on a preterm child with distinct clinical manifestations of zinc deficiency confirmed by histology and laboratory analysis who quickly healed with oral zinc therapy.

Transient symptomatic zinc deficiency in a breast-fed preterm infant

Transient, symptomatic zinc deficiency in breast-fed, low-birthweight infants is a rare, but probably underrecognized disorder hallmarked by periorificial and acral dermatitis. Unlike in acrodermatitis enteropathica, symptoms disappear when nursing ends. We report a breast-fed, preterm infant with demarcated, erythematous, and exudative patches with overlying crusts on the perioral, perianal, and acral areas. Laboratory investigations revealed lowered zinc levels in the infant's serum, but normal levels in his mother's milk. Oral zinc supplementation resulted in total clearing of skin lesions within 4 weeks. Our patient's presentation illustrates the importance of zinc in rapidly growing preterm infants and aims to stimulate awareness for this disorder. Symptomatic zinc deficiency can be easily diagnosed by careful examination and effectively treated with oral zinc substitution.

Zinc-deficiency dermatitis in breast-fed infants

We report ten infants (mean gestational age: 30 weeks; range: 25 to 40 weeks) with zinc deficiency dermatitis who developed erosive, impetiginized periorificial dermatitis at 10 weeks of age (corresponding to a mean gestational age of 41.4 weeks, with a range of 36-44 weeks), but who were otherwise well. Cutaneous symptoms were initially misdiagnosed as eczema or impetigo in 8/10 (80%) children who received either topical (4/8) and/or systemic (6/8) antibiotics. Topical corticosteroids were applied in 4/10 infants for a mean time of 4 weeks (range: 2 to 5 weeks) before the correct diagnosis was established by decreased serum zinc levels; skin atrophy (telangiectasia, thinning) as a complication of topical steroid treatment (class II steroids) was observed in two infants. All children responded to oral therapy with zinc sulfate or zinc gluconate (1.5-4 mg/kg/d). Skin lesions started to clear within 24 h after the initiation of therapy and had completely cleared in all infants after 14 days of therapy (range: 3-14 days). We conclude that nutritional zinc deficiency is a frequently misdiagnosed problem in thriving, fully breast-fed preterm babies. It is attributable to the decreased zinc content of human milk as compared to cow's milk, and the increased demand of zinc in rapidly thriving preterm infants. It seems advisable to routinely check serum zinc levels in fully breast-fed preterm infants who do not receive regular oral zinc supplementation once they reach a gestational age of 40 weeks.

Acrodermatitis enteropathica and an overview of zinc metabolism

Acrodermatitis enteropathica is a rare autosomal recessive disorder of zinc deficiency. The genetic defect has been mapped to 8q24 and the defective gene identified as SLC39A4, which encodes the zinc transporter Zip4. The diagnosis is made by way of clinical presentation together with histopathology and laboratory tests. Here we provide an overview of zinc metabolism and a description of inherited and acquired zinc deficiency.

Levels of cytokines (IL-1beta, IL-2, IL-6, IL-8, TNF-alpha) and trace elements (Zn, Cu) in breast milk from mothers of preterm and term infants

It has been well documented that human milk contains several immunomodulator components which are important during infant period when the newborn's immune system is still under development. In this study, we aim at examining levels of cytokines, zinc (Zn), and copper (Cu) in milk from mothers of premature and mature infants, and comparing changes during lactation periods consequently. Milk was collected from total of 40 mothers (group M: mothers of mature infants, n = 20; group PM: mothers of premature infants, n = 20) from four lactation stages: colostrum (0–7 days), transitional (7–14 days), mature milk (21 days), and mature milk (2nd month). Levels of cytokines (interleukin [IL]-lβ, IL-2, IL-6, IL-8, tumor necrosis factor-alpha [TNF-α]) were determined by chemiluminesence method, whereas atomic absorption spectrophotometer was used for the determination of Zn and Cu levels. Cytokine levels were determined to be high in colostrum and transient milk from mothers of full-term infants, whereas their levels were reduced drastically in the 21st day and the 2nd month milk (P < .01 , P < .001). Similar trends were observed in milk from mothers of premature infants, but cytokine levels were significantly lower in colostrum compared to colostrum from mothers of mature infants (P < .01). The differences in cytokine levels were continuous in transient milk (P < .05) and mature milk (21 days) (P < .05), whereas there was no statistically significant differences between milk from both groups of mothers in the 2nd month (P > .05). Zn levels in milk from mothers of premature infants were significantly lower compared to the ones from mothers of mature infants (P < .01) and these differences continued through the 2nd month. Although Cu levels were lower in milk from mothers of premature infants, there was no statistically significant difference except colostrum (P > .05). Our results clearly demonstrate that the level of immunomodulating agents such as cytokines and trace elements in milk from mothers of premature infants is less than the level of the same agents in milk from mothers of full-term infants. Although there are commercially available products for infant feeding, human milk is still the best natural nutrient for newborns. Therefore, when premature infants are breastfed, necessary precautions such as supplemantary diets must be considered for possible infections and risks related with immune system deficiency.

The role of zinc in the growth and development of children

This review concerns the importance of zinc in growth, development, and cognitive function in children and the deleterious consequences of its deficiency on children's health. Possible strategies to overcome zinc deficiency and the results of some supplementation trials are discussed.

Nutritional zinc balance in extremely low-birth-weight infants

BACKGROUND

Zinc is important for metabolism, cell growth, immunity, and defense against oxygen radicals. Extremely low-birth-weight (< 1000 g) infants have higher nutritional needs, but information on zinc is scarce. The authors performed nutritional balances in 10 infants with birth weights of 500 to 999 g and who were fed with fortified human milk.

METHODS

The authors collected infant feces, urine, and blood and human milk samples during 72 hours at 7 and 12 weeks of age. Zinc concentration was measured by inductively coupled plasma-mass spectrophotometry, atomic emission spectrophotometry, and instrumental neutron activation analysis.

RESULTS

Mean (SD) intake via human milk was 379 (+/- 373) microg x kg(-1) x d(-1) during both balances. Urinary excretion was high at 7 weeks of age, decreased to half at 12 week, and was negatively correlated (P < 0.01) with weight gain. Mean absorption was slightly positive at 7 weeks of age but zero or negative in most infants at 12 weeks of age. Retention was negative in all infants at both observation periods, except in one infant during the second balance. Clinical zinc deficiency developed in one infant at 12 weeks of age.

CONCLUSIONS

Zinc balances in extremely low-birth-weight infants are highly variable and usually negative. Controlled trials are needed to assess need for and benefits and risks of zinc supplementation.

Acrodermatitis enteropathica-like eruption in an infant with nonketotic hyperglycinemia

Acrodermatitis enteropathica is a rare inherited disorder characterized by zinc deficiency and a triad of dermatitis, diarrhea, and alopecia. It is an autosomal recessive condition thought to be due to the inability to absorb zinc from the gastrointestinal tract. Acquired zinc deficiency due to a variety of etiologies may produce a similar clinical picture. These causes include inadequate supply, malabsorption, and low zinc stores. In addition to zinc, deficiencies of other nutrients such as branched chain amino acids have induced an acrodermatitis enteropathica-like eruption. We describe a case of a 26-month-old boy with a rare inborn error of metabolism known as nonketotic hyperglycinemia who developed an acrodermatitis enteropathica-like eruption. In addition to zinc deficiency, the patient was deficient in branched chain amino acids due to a low protein diet instituted to reduce his elevated glycine levels. The rash did not respond to zinc replacement alone, and therefore is most likely a combination of amino acid and zinc deficiency. Acrodermatitis enteropathica-like eruptions have been described in other conditions that cause decreased serum amino acids, such as maple syrup urine disease and organic acidurias. This is the first case describing an association between acrodermatitis enteropathica and nonketotic hyperglycinemia.

Zinc and copper in preterm neonates: relationship with breast milk

The study was conducted to assess copper and zinc levels in neonate's serum, mother's serum, neonate's hair and urine and to ascertain association between them. It is of concern whether zinc and copper deficiency is present at birth and maternal blood and breast milk zinc and copper levels have any effect on this. The study sample included 155 neonates with gestational age 26-41 wks and birth weight 0.550-3.800 kg. Mother's serum, breast milk, neonate's serum, hair, urine samples were analysed for zinc and copper by atomic absorption spectrophotometry. Gestational age was estimated either singly or by combination of date of last normal menses, fetal ultrasonography, and postnatal measures of physical and neurological development by clinical examination and weight by Secca electronic balance. The neonates were classified into term and preterm, small (SGA) and appropriate for gestational age (AGA). Neonates over 37 wks and 2.5 kg served as controls. To assess the dependency, relationship and effectiveness of quantitative predictive variables on the predictions of values, multiple regression analysis was used. Neonates between 26-30 wks gestational age and < 2.5 kg birth weight had significantly low serum zinc and copper. Breast milk zinc was low in mothers delivering preterm and < 2.5 kg neonates. Urinary copper and zinc levels were high in preterm appropriate for gestational age (Pre AGA) than term neonates. Multiple regression analysis revealed that neonate's serum Cu, serum Zn, hair Cu, hair Zn, urine Cu and urine Zn had contribution variability of 49.8%, 51.8%, 49.2%, 16.6%, 52.2% and 68.9%, respectively. The effect of mother's serum, breast milk, and neonate's serum copper and zinc collectively was significant for serum copper (F = 29.59) and hair zinc (F = 32.03). Preterm and low birth weight infants during subsequent growth and development should be supplemented with zinc and copper when on breast feeding.

Study of interleukin-6 and tumor necrosis factor-alpha levels in maternal serum and amniotic fluid of patients with premature rupture of membranes

To study the change and clinical significance of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) levels in the maternal serum and amniotic fluid of pregnant women with chorioamnionitis and with premature rupture of membranes. Twenty-six normal-term pregnant women formed the control group, and forty-six pregnant women with premature rupture of membranes were enrolled for the study. Maternal serum and amniotic fluid IL-6 and TNF-alpha levels were measured using a sensitive radioimmunoassay and enzyme-linked immunosorbent assay (ELISA); chorioamnionitis was diagnosed by fetal membrane pathology. The maternal serum IL-6 levels and amniotic fluid IL-6 and TNF-alpha levels were higher than those of the control (P < 0.01). There was a significant relationship between maternal serum IL-6 and maternal serum and amniotic fluid IL-6 and TNF-alpha with the time of the premature rupture of membranes, i.e. the longer the time, the higher the maternal serum and amniotic fluid IL-6 and TNF-alpha. There were 12 patients with chorioamnionitis in premature rupture of membranes and their maternal serum and amniotic fluid IL-6 and TNF-alpha levels were higher than that of non-chorioamnionitis patients (P < 0.01-0.05). IL-6 and TNF-alpha levels in maternal and amniotic fluids are a valuable index in identification of the chorioamnionitis in patients with premature rupture of membranes.

Identification of an alpha2-macroglobulin receptor in human mammary epithelial cells

Several cases of zinc (Zn) deficiency in human infants caused by abnormally low concentrations of Zn in breast milk were recently reported, the underlying mechanism of which is not known. Alpha2-macroglobulin (alpha2-M), a major Zn-binding ligand in serum, presents a potential vehicle for mammary Zn uptake. This study was conducted to determine if an alpha2-M receptor is present in human mammary epithelial cells, where it may be involved in the endocytosis of alpha2-M into the mammary gland. Normal human mammary epithelial cells were grown to confluency in serum-free medium. For all binding and uptake studies, alpha2-M, preactivated with methylamine and labeled with 125I, was added to cells for varied lengths of time to determine saturation over time and at varied concentrations to determine saturation over increasing concentration of ligand. Nonspecific and competitive binding were measured by addition of a 100-fold molar excess of unlabeled alpha2-M and serum albumin or lactoferrin, respectively. Binding at 4 degreesC was specific for alpha2-M and approached saturation kinetics at 56 nmol/L. Scatchard plot analysis of the binding data demonstrated more than one binding site: a high affinity, saturable binding site and a low affinity, nonsaturable binding site. Uptake of alpha2-M at 37 degreesC was rapid and continuous over increasing concentrations of alpha2-M, and internalized alpha2-M was rapidly degraded. Results from this study present evidence for receptor-mediated uptake of alpha2-M in human mammary epithelial cells, which in turn, provides a potential mechanism for Zn acquisition by the cell.

Detecting subclinical deficiency of essential trace elements in children with special reference to zinc and selenium

OBJECTIVE

This article reviews situations in which we should be alert to the risk of trace element deficiencies, and the difficulties of assessing trace element status, as illustrated by states of potential subclinical deficiency of zinc and selenium in infants.

CONCLUSION

Deficiency states of many trace elements have been documented in infants, and there is probably an underdiagnosed group of infants with subclinical deficiency, from which however the great majority are protected by effective regulatory systems. Specific, sensitive, and reliable methods are needed for the detection of trace element imbalances.

Copper and zinc content in human milk in Croatia

The aim of this paper was to research whether there had been any statistically significant difference in the content of Cu and Zn in human milk depending on the social status of women (refugee and non-refugee), age, number of deliveries, days after delivery, weight gained by nursing women and smoking habits, as well as whether the infants had received sufficient quantities of these elements. The elements were determined by flame atomic absorption spectrometry. The samples were collected in the Clinical Hospital Osijek and Refugee Centre Nabrde, near Osijek, Eastern Croatia. The Cu in human milk ranged from 0.27 mg/l to 1.35 mg/l, and Zn from 0.62 mg/l to 15.0 mg/l. The mean levels of Cu and Zn for each group, formed according to the results of the questionnaire are presented too. Calculated daily dietary intake of these elements accords with the RDA.