Zinc and iron adequacy and relative importance of zinc/iron storage and intakes among breastfed infants

Breastmilk mineral composition among well-educated mothers from Central Poland - Associations with maternal dietary intake, dietary patterns and infant psychomotor development

BACKGROUND

Maternal dietary habits could affect breastmilk mineral composition, which may influence infant development. Mineral dietary intake or supplementation slightly affects its breastmilk concentration. However, the intake of selected food groups or dietary patterns that reflect diet complexity could have a greater impact. Hence, the aim of the study was to assess breastmilk mineral composition at one, three, and six months of lactation among mothers living in urban area of Central Poland, as well as the evaluate maternal dietary determinants and associations with infant anthropometric and psychomotor development.

METHODS

The study was conducted among 43 healthy and exclusively breastfeeding mothers. In the first, third, and sixth months of lactation, we collected breastmilk samples and assessed the concentration of Ca, P, Zn, Fe, Se, Ni, As, Pb, and Cd using the ICP-MS method. Maternal dietary habits were evaluated by a food frequency questionnaire in the first month of lactation, whereas in the third and sixth by the three-day food record. Based on the collected data adherence to the Polish-adapted Mediterranean (Pl-aMED; 1 month) and the DASH diet (Mellen's Index; 3 and 6 months) was assessed. In the third and sixth months of lactation infant anthropometric parameters and the sixth month of lactation psychomotor development were evaluated.

RESULTS

Breastmilk Se, Ni, As, Pb, and Cd levels were under the LOQ in all the breastmilk samples at all study visits. Median breastmilk mineral concentrations of Ca, P, Zn, and Fe in the first, third, and sixth months of lactation varied from 381.9 to 332.7 mg/L, 161.6 to 139.1 mg/L, 2.2 to 0.8 mg/L, and 0.26 to 0.17 mg/L, respectively. Maternal dietary intake and supplementation did not affect breastmilk Ca, P, Zn, and Fe. Pl-aMED scores were associated with breastmilk Ca (β = 0.489, 95% CI 0.180 - 0.799, p = 0.003) and Zn (β = 0.499, 95% CI 0.199 - 0.798, p = 0.002) in the first month of lactation, whereas no association with the DASH diet were observed in the third and sixth month of lactation. Breastmilk Fe in the third month was associated with infant motor development (β = 0.420, 95% CI 0.113 - 0.727, p = 0.009) in the sixth month of life, but no other associations with anthropometric or psychomotor development were observed. Moreover, we estimated that few infants meet their adequate intake (AI) requirements for P, Zn, and Fe.

CONCLUSION

Our study showed that maternal adherence to Pl-aMED is a significant predictor of breastmilk Ca and Zn in the first month of lactation, which may be especially important considering that more than 75% of infants had inadequate Zn intake. Moreover, we found that breastmilk Fe positively influenced infant motor development, despite the majority of infants having inadequate intake. On the other hand, no infant had deficiency symptoms, which emphasizes the necessity to evaluate of AI norms for infants.

Human Milk Micronutrients and Child Growth and Body Composition in the First 2 years: A Systematic Review

Human milk (HM) provides a plethora of nutritional and non-nutritional compounds that support infant development. For many compounds, concentrations vary substantially among mothers and across lactation, and their impact on infant growth is poorly understood. We systematically searched MEDLINE, Embase, the Cochrane Library, Scopus, and Web of Science to synthesize evidence published between 1980 and 2022 on HM components and anthropometry through 2 y of age among term-born infants. Outcomes included weight-for-length, length-for-age, weight-for-age, body mass index (in kg/m2)-for-age, and growth velocity. From 9992 abstracts screened, 144 articles were included and categorized based on their reporting of HM micronutrients, macronutrients, or bioactive components. Micronutrients (vitamins and minerals) are reported here, based on 28 articles involving 2526 mother-infant dyads. Studies varied markedly in their designs, sampling times, geographic and socioeconomic settings, reporting practices, and the HM analytes and infant anthropometrics measured. Meta-analysis was not possible because data were sparse for most micronutrients. The most-studied minerals were zinc (15 articles, 1423 dyads) and calcium (7 articles, 714 dyads). HM iodine, manganese, calcium, and zinc concentrations were positively associated with several outcomes (each in ≥2 studies), whereas magnesium (in a single study) was negatively associated with linear growth during early lactation. However, few studies measured HM intake, adjusted for confounders, provided adequate information about complementary and formula feeding, or adequately described HM collection protocols. Only 4 studies (17%) had high overall quality scores. The biological functions of individual HM micronutrients are likely influenced by other HM components; yet, only 1 study analyzed data from multiple micronutrients simultaneously, and few addressed other HM components. Thus, available evidence on this topic is largely inconclusive and fails to address the complex composition of HM. High-quality research employing chronobiology and systems biology approaches is required to understand how HM components work independently and together to influence infant growth and to identify new avenues for future maternal, newborn, or infant nutritional interventions.

Predictors of Breast Milk Zinc Levels Among Breastfeeding Women in Palestine: a Cross-Sectional Study

Zinc is one of the most important essential micronutrients that is needed for the normal growth, development, and maintaining the health of human beings. Previous studies showed that zinc deficiency was highly prevalent among pregnant and lactating women. This cross-sectional study was conducted to determine breast milk zinc levels among breastfeeding women in Palestine and to identify the predictors of breast milk zinc levels. Breast milk samples were obtained from breastfeeding women who visited maternity and primary healthcare centers. Zinc levels were determined using inductively coupled plasma mass spectrometry. Breast milk zinc levels were determined in 390 breast milk samples. The mean breast milk zinc level in all samples was 0.15 ± 0.09 mg per 100 mL. Breast milk zinc levels declined with postpartum time from 0.22 ± 0.011 at ≤ 1 month postpartum to 0.09 ± 0.009 mg per 100 mL at > 9 months postpartum (p-value < 0.001). Multiple linear regression showed that high breast milk zinc levels were predicted by younger maternal age, postpartum time, being employed, frequent consumption of multivitamins/minerals, and practicing exclusive breastfeeding. In conclusion, the breast milk zinc levels quantified among breastfeeding women in Palestine were comparable to those previously reported among non-malnourished women elsewhere. The findings of this study are informative to pediatricians, gynecologists, nurses/midwives, breastfeeding advisors/counselors, nutritionists, and policymakers who might be interested in designing and implementing interventions to improve breast milk zinc levels.

Dynamics of human milk oligosaccharides in early lactation and relation with growth and appetitive traits of Filipino breastfed infants

Human milk oligosaccharides play a key role in the maturation of the infant gut microbiome and immune system and are hypothesized to affect growth. This study examined the temporal changes of 24 HMOs and their associations to infant growth and appetitive traits in an exploratory, prospective, observational, study of 41 Filipino mother-infant dyads. Exclusively breastfed, healthy, term infants were enrolled at 21-26 days of age (≈ 0.75 mo) and followed for 6 months. Infant growth measures and appetitive traits were collected at visit 1 (V1) (≈ 0.75 mo), V2 (≈ 1.5 mo), V3 (2.5 mo), V4 (2.75 mo), V5 (4 mo), and V6 (6 mo), while HMOs were measured at V1, V2, V3 and V5. Overall exposure to each HMO was summarized as area under the curve from baseline to 4 months of age and examined in association with each measure of growth at 6 months using linear regression adjusted for maternal age at birth, infant sex, birth weight, and mode of delivery. We saw modest associations between several HMOs and infant growth parameters. Our results suggest that specific HMOs, partly as proxy for milk groups (defined by Secretor and Lewis status), may be associated with head circumference and length, increasing their relevance especially in populations at the lower end of the WHO growth curve. We did not identify the same HMOs associated with infant appetitive traits, indicating that at least in our cohort, changes in appetite were not driving the observed associations between HMOs and growth.Clinical trial registration: NCT03387124.

Zinc and iron adequacy and relative importance of zinc/iron storage and intakes among breastfed infants

Neonatal nutrient storage and supplies from breast milk contribute to nutrient status and growth of infants during their early life. This study investigated the adequacy of zinc and iron intakes among breastfed infants during the first 4 months and determined the relative importance of zinc/iron storage versus nutrient intakes with infant's biochemical status and growth. A longitudinal study followed lactating women and their breastfed infants from birth to 4 months postpartum. Cord zinc and ferritin concentrations, as indicators of nutrient storages, were determined. Zinc and iron intakes from breast milk were determined by measurement of breast milk volume together with milk zinc and iron concentrations at 2 and 4 months postpartum. Inadequacy of nutrient intakes was determined using average requirement (AR) which were 1.6 and 0.24 mg/day for zinc and iron respectively. Infant's serum zinc and ferritin were determined at 4 months of age. The data were collected from 64 and 56 participants at 2 months and 4 months postpartum. Inadequate zinc intake was found in 14.5 and 40% of infants at 2 and 4 months old, respectively. The prevalence of biochemical zinc and iron deficiency in infants were 76 and 11%, respectively. Iron endowment was significantly associated with serum ferritin at 4 months. The cumulative zinc intake was positively associated with weight gain and weight-for-length Z-score, but not length. This study provides quantitative data on zinc and iron intakes, and demonstrates the relative importance of nutrient storage versus intakes on biochemical status and growth of breastfed infants.

Association of Infant Feeding Practices with Iron Status and Hematologic Parameters in 6-Month-Old Infants

Background: Infants’ feeding practices in the first 6 months of life and their association with iron status and hematologic parameters has not been well studied. We aim to evaluate this association. Methods: In a retrospective chart review, we identified 403 infants who received laboratory screening for anemia at 6-month visits. Infants were categorized into four groups according to feeding practices. Hematologic parameters and incidence of anemia, iron deficiency (ID), and iron deficiency anemia (IDA) were compared. Results: In total, 105 infants were breastfed (BF), 78 were breastfed with iron supplementation starting at 4 months (BI), 109 were mixed-fed (breast milk and formula) with or without iron supplementation (MF), and 111 were formula-fed (FF). The BF group had the highest incidence of anemia (38.1%), ID (28.6%), and IDA (17.1%) when compared with the other groups (p < 0.001). In multivariate logistic regression, BI, MF, and FF infants had 90.4%, 97.5%, and 96.9% decreased risk of IDA, respectively, with BF infants as a reference group. Conclusion: The incidence of anemia, ID, and IDA at age 6 months was higher in BF than FF or MF infants. However, iron supplements in BF infants starting at 4 months significantly reduced their ID and IDA incidence.