Total antioxidant activity and trace elements in human milk: the first 4 months of breast-feeding

The association of maternal food quality score (FQS) with breast milk nutrient content and antioxidant content of infant urine: a cross-sectional study

BACKGROUND

Breast milk (BM) is a complex fluid with a variable composition within women over time and between women in the population. The BM compositional differences are likely to be partly due to maternal dietary patterns. This study aimed to evaluate food quality score (FQS) in lactating mothers and its association with quality indicators of BM and antioxidant content of infant urine.

METHODS

This cross-sectional study was undertaken in 350 lactating women aged 20 to 35 years. Data on dietary intake was collected using a validated food frequency questionnaire (FFQ) containing 65 food items. The FQS was calculated by integrating the scores obtained from healthy and unhealthy food groups. Subjects were categorized according to FQS adherence, with the greatest adherence being allocated to the third tertile and those with the lowest FQS in the first tertile. Antioxidant activity of the BM and infant urine samples was assessed using the Ferric reducing antioxidant power (FRAP), 2, 2'-diphenyl-1-picrylhydrazyl (DPPH), thiobarbituric acid reactive substances (TBARs), and Ellman's assay. The total content of BM protein, calcium, and triglyceride was measured using standard biochemical kits.

RESULTS

BM from mothers from the third tertile of FQS contained significantly higher DPPH, thiol, calcium, and protein levels compared to BM from those in the lowest tertile (p˂0.05). Infant urinary DPPH and FRAP was also significantly higher in the highest tertile vs. the lowest tertile (p˂0.05).

CONCLUSION

High maternal adherence to the FQS was associated with a high BM quality and antioxidant content of infant urine.

A Mediterranean diet is associated with improved total antioxidant content of human breast milk and infant urine

BACKGROUND

The composition of breast milk (BM) is dynamic and can be influenced by maternal variables that include the diet and nutritional status. This study examined the association between maternal adherence to a Mediterranean diet (MedDiet) and total antioxidant content of BM and infant urine.

METHODS

We collected 350 BM samples from mothers and urine samples from their infants. The dietary intakes of the mothers were recorded using a validated 65 items-food frequency questionnaire (FFQ). The total antioxidant status of the samples was assessed using the ferric reducing/antioxidant power (FRAP), the 1, 1-diphenyl-2-picrylhydrazyl (DPPH), thiobarbituric acid reactive substances (TBARS), and thiol quantification assays. Milk protein, calcium, and triglyceride (TG) were also determined using standard biochemical kits.

RESULTS

Subjects with the highest MedDiet scores were among the women in the highest tertile (T3) for consumption of dietary fiber, fruits, vegetables, nuts, legumes, and seeds, low-fat dairy, whole grains, and the lowest consumption of red meat, sweetened beverages, and sodium, compared to women in the first tertile (T1) with the lowest MedDiet scores. After adjustment for potential confounders, the individuals in the highest tertile for MedDiet score had a significantly higher level of milk DPPH, and infant urinary DPPH than the lowest tertile and had a significantly higher level of milk protein, FRAP and infant urinary FRAP compared to the T2 (P < 0.05). In addition, the mothers in the T3 for the MedDiet pattern had a significantly lower level of milk TG compared to those within the T1 (P < 0.05).

CONCLUSION

Our findings show that a high maternal adherence to a MedDiet can affect BM composition and their infants' urine.

Toxic metal and trace element status in the breast milk of Turkish new-born mothers

BACKGROUND AND AIM

This study aims to evaluate the toxic metal and trace element concentrations in breast milk obtained from new-born nursing mothers in rural Giresun province, located on the coast of the Black Sea.

METHODS

Milk samples were randomly collected once from early lactation of 50 nursing mothers. Inductively coupled plasma mass spectrometry was used to analyse the concentrations of iron (Fe), nickel (Ni), manganese (Mn), cobalt (Co), chromium (Cr), copper (Cu), zinc (Zn), arsenic (As), molybdenum (Mo), cadmium (Cd) and lead (Pb) in the breast milk. Shapiro-Wilk test was used to evaluate the distribution of data. The Pearson-J correlation was used for normally distributed elements, and Spearman correlation analysis was used for others.

RESULTS

The mean amounts of elements were 3.36 µg kg^-1 of Cr, 9.26 µg kg^-1 of Mn, 797 µg kg^-1 of Fe, 1.99 µg kg^-1 of Ni, 5.92 µg kg^-1 of Cu, 379 µg kg^-1 of Zn and 2.23 µg kg^-1 of Pb. Co, As, Mo and Cd concentrations were below the detection limit. A highly significant correlation was found between iron and Nickel in breast milk.

CONCLUSION

Our findings were evaluated in comparison with the WHO data, and whether they were in accordance with the recommended Dietary Reference Intake (DRI) values for 0-6-months-old infants was calculated. Pb levels were similar to those of WHO, while As and Cd were below the measurable limit. Fe, Mn, and Cr concentrations were higher than WHO data, while Co, Ni, Cu and Zn were lower. This research is the first study conducted in this region.

Lead (Pb) and neurodevelopment: A review on exposure and biomarkers of effect (BDNF, HDL) and susceptibility

Lead (Pb) is a ubiquitous environmental pollutant and a potent toxic compound. Humans are exposed to Pb through inhalation, ingestion, and skin contact via food, water, tobacco smoke, air, dust, and soil. Pb accumulates in bones, brain, liver and kidney. Fetal exposure occurs via transplacental transmission. The most critical health effects are developmental neurotoxicity in infants and cardiovascular effects and nephrotoxicity in adults. Pb exposure has been steadily decreasing over the past decades, but there are few recent exposure data from the general European population; moreover, no safe Pb limit has been set. Sensitive biomarkers of exposure, effect and susceptibility, that reliably and timely indicate Pb-associated toxicity are required to assess human exposure-health relationships in a situation of low to moderate exposure. Therefore, a systematic literature review based on PubMed entries published before July 2019 that addressed Pb exposure and biomarkers of effect and susceptibility, neurodevelopmental toxicity, epigenetic modifications, and transcriptomics was conducted. Finally included were 58 original papers on Pb exposure and 17 studies on biomarkers. The biomarkers that are linked to Pb exposure and neurodevelopment were grouped into effect biomarkers (serum brain-derived neurotrophic factor (BDNF) and serum/saliva cortisol), susceptibility markers (epigenetic markers and gene sequence variants) and other biomarkers (serum high-density lipoprotein (HDL), maternal iron (Fe) and calcium (Ca) status). Serum BDNF and plasma HDL are potential candidates to be further validated as effect markers for routine use in HBM studies of Pb, complemented by markers of Fe and Ca status to also address nutritional interactions related to neurodevelopmental disorders. For several markers, a causal relationship with Pb-induced neurodevelopmental toxicity is likely. Results on BDNF are discussed in relation to Adverse Outcome Pathway (AOP) 13 ("Chronic binding of antagonist to N-methyl-D-aspartate receptors (NMDARs) during brain development induces impairment of learning and memory abilities") of the AOP-Wiki. Further studies are needed to validate sensitive, reliable, and timely effect biomarkers, especially for low to moderate Pb exposure scenarios.

Study of the phenolic compound profile and antioxidant activity of human milk from Spanish women at different stages of lactation: A comparison with infant formulas

Human milk (HM) has been proven to have important and essential antioxidant properties to counteract infant susceptibility to oxidative stress. Phenolic compounds are secondary metabolites which come from plants and are potent natural antioxidants. The ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method used in the present study allowed the quantification of 26 phenolic compounds (ten hydroxybenzoic acids, seven hydroxycinnamic acids, four flavonoids, three hydroxybenzaldehydes and two other polyphenols) in HM samples at different stages of lactation (colostrum, transitional milk and mature milk) and infant formulas (IF). Many of the phenolic compounds identified have been reported to be present in HM for the first time. The total phenolic compound content (TPC) was quantified using the Folin assay and the antioxidant activity (AC) was evaluated with the DPPH, ABTS and FRAP assays. Significant differences were evidenced between HM and IF. HM from mothers with an adherence to a Mediterranean diet contained twice as many individual phenolic compounds as infant formulas, with a higher proportion of hydroxybenzoic acids. Conversely, IF showed a higher proportion of hydroxycinnamic acids. Overall, the antioxidant activity of HM showed small variations during lactation.

Impact of delivery mode on the levels of essential trace elements in breast milk

Aim: This study investigated whether the parturition mode (vaginal or cesarean [C-] section) affects breast milk concentrations of four essential trace elements (iron, copper, zinc, and manganese).Methods: Women giving birth at seven hospitals in seven different regions of China were enrolled in the study. Each participant provided breast milk, collected on postpartum day 3-5, for determination of iron, copper, zinc, and manganese concentrations. Breast milk concentrations of the subject trace elements were compared between women giving birth vaginally or via C-section.Results: Of the 1243 women enrolled in the study, 617 (49.6%) gave birth via the vaginal route and 626 (50.4%) delivered via C-section. The mean milk concentrations of iron, copper, zinc, and manganese in the milk of women delivering via the vaginal route were higher than those in the milk of women delivering via C-section; only the copper concentration differences were statistically significant, after adjusting for confounding factors (p = .023).Conclusion: Delivery mode impacts breast milk concentrations of essential trace elements, with vaginal delivery being associated with higher essential trace element concentrations than C-sections.

Total antioxidant status in fresh and stored human milk from mothers of term and preterm neonates

BACKGROUND

Antioxidant defense of the body is assured by both endogenous and exogenous factors comprising several enzymes, vitamins, protein components and derivates and oligoelements. Breast milk has been proven to have important and essential antioxidant composition to prevent and protect against diseases in infancy. The objective of this study was to determine the total antioxidant status (TAS) of human milk and to evaluate the differences between premature milk and term milk at different moments of lactation (colostrum, transitional milk and mature milk). A second objective was to evaluate how TAS varies whether the human milk is refrigerated or frozen.

METHODS

Pumped human milk samples of the third, seven and 30th day were collected from women who had term deliveries (30 cases) and preterm deliveries (60 cases). Samples were refrigerated (+4 °C) or frozen in domestic conditions (-20 °C) for various durations and TAS was determined using the ABTS® technique with Randox® reagents and compared for the two groups.

RESULTS

Higher values were found in term versus preterm fresh milk at 30 days of lactation. A slight reduction in TAS was found after 72 h of refrigeration, while 1 week freezing produced significant decrease of total antioxidants. Freezing for 12 weeks reduced more than 50% of TAS in fresh milk.

CONCLUSION

Breastfeeding provides the optimal antioxidant for neonates, regardless of gestational age. Fresh milk has the higher antioxidant power. When it is not available, refrigerated milk for 24 h is better than for 72 h and preferable than frozen milk. Freezing human milk for 3 months in household conditions markedly diminishes TAS.

Zinc Content in Breast Milk and Its Association with Maternal Diet

Background: Zinc is an indispensable element, being involved in many biological processes. Correspondingly, insufficient zinc intake in early youth can detrimentally affect the function of a growing body. The aim of this study was to determine zinc content in breast milk among lactating women in Latvia and factors (maternal diet; mother’s and baby’s characteristics; breastfeeding pattern) affecting it. Methods: In total, 62 mature milk (at least one month postpartum) samples were collected and pooled within 24 h. Zinc content (mg 100 mL⁻¹) was determined using inductively coupled plasma mass spectrometry (ICP-MS; Agilent 7700×, Agilent Technologies, Tokyo, Japan). Results: Zinc content in mature breast milk ranged from 0.01 to 0.34 mg 100 mL⁻¹ with a median (interquartile range) content of 0.10 (0.05–0.15) mg 100 mL⁻¹. Time postpartum was a significant negative predictor for zinc content in breast milk (r = −0.500; p = 0.000). Median maternal zinc intake was 10.70 (7.24–15.27) mg. Yet, zinc content in breast milk was unaffected by maternal dietary zinc intake (r = 0.155; p = 0.221). Conclusions: Maternal dietary zinc intake was nearly the recommended intake for lactating women (11 mg), but due to low zinc content in breast milk, babies in Latvia might not receive sufficient zinc intake. Future research should aim for the assessment of zinc status by evaluating plasma or serum levels of both mothers and babies.

Validation of a dilute and shoot method for quantification of 12 elements by inductively coupled plasma tandem mass spectrometry in human milk and in cow milk preparations

Nutritional information about human milk is essential as early human growth and development have been closely linked to the status and requirements of several macro- and micro-elements. However, methods addressing whole mineral profiling in human milk have been scarce due in part to their technical complexities to accurately and simultaneously measure the concentration of micro- and macro-trace elements in low volume of human milk. In the present study, a single laboratory validation has been performed using a "dilute and shoot" approach for the quantification of sodium (Na), magnesium (Mg), phosphorus (P), potassium (K), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), selenium (Se), molybdenum (Mo) and iodine (I), in both human milk and milk preparations. Performances in terms of limits of detection and quantification, of repeatability, reproducibility and trueness have been assessed and verified using various reference or certified materials. For certified human milk sample (NIST 1953), recoveries obtained for reference or spiked values are ranged from 93% to 108% (except for Mn at 151%). This robust method using new technology ICP-MS/MS without high pressure digestion is adapted to both routinely and rapidly analyze human milk micro-sample (i.e. less than 250 μL) in the frame of clinical trials but also to be extended to the mineral profiling of milk preparations like infant formula and adult nutritionals.

Use of human milk in the assessment of toxic metal exposure and essential element status in breastfeeding women and their infants in coastal Croatia

Pregnant and lactating women and infants are vulnerable population groups for adverse effects of toxic metals due to their high nutritional needs and the resultant increased gastrointestinal absorption of both, essential and toxic elements. Although breastfeeding is recommended for infants worldwide, as human milk is the best source of nutrients and other required bioactive factors, it is also a pathway of maternal excretion of toxic substances including toxic metals and thus a source of infant exposure. The aim of this research was to assess health risks in breastfeeding women in the coastal area of the Republic of Croatia and their infants (N=107) due to maternal exposure to Cd and Pb via cigarette smoking, and Hg via seafood and dental amalgam fillings, and their interaction with essential elements. Biological markers of exposure were the concentrations of main toxic metals Pb, Cd and Hg in maternal blood and three types of breast milk throughout lactation stages. Biological markers of effects were the levels of essential elements Ca, Fe, Cu, Zn and Se in maternal serum and breast milk. With regard to cigarette smoking as a source of exposure to Cd and Pb, there were effects of smoking on Cd concentration in blood and correlations between the smoking index and Cd concentrations in maternal blood (ρ=0.593; P<0.001) and mature milk (ρ=0.271; P=0.011) and Pb concentration in transitional milk (ρ=0.280; P=0.042). Regarding fish, we found correlations between weekly consumption frequency and total Hg concentrations in maternal blood (ρ=0.292; P=0.003) and mature milk (ρ=0.303; P=0.003). The number of dental amalgam fillings correlated with total Hg concentrations in colostrum (ρ=0.489; P=0.005) and transitional milk (ρ=0.309; P=0.018). As for the essential element status, only Se levels in maternal serum decreased by 10% in persons who continued smoking during pregnancy compared to non-smokers. In conclusion, the levels of main toxic metals Cd, Pb and Hg and essential elements Ca, Fe, Cu, Zn and Se in maternal blood and three types of breast milk samples in the studied area of coastal Croatia showed no risk of disrupted essential element levels with regard of toxic metal exposure in both breastfeeding women and their infants.

Is variation in total antioxidant capacity of human milk associated with levels of bio-active proteins?

OBJECTIVE

As the antioxidant properties of human milk may be beneficial for very preterm-born infants, it is important to identify the association between total antioxidant capacity (TAC) and bio-active proteins.

STUDY DESIGN

Breast milk was prospectively collected (four times) on postpartum days 6 to 8, 13 to 15, 20 to 22 and 27 to 29 from 15 mothers who had delivered between 24 and 31 weeks of gestation. Skimmed milk was assayed to measure TAC and bio-active proteins (lysozyme, lactoferrin, leptin and adiponectin). The association between TAC and levels of bio-active proteins during the first month of lactation was analyzed in a regression model.

RESULT

Coefficient of determinations (R(2)) revealed an overall effect of bio-active proteins on breast milk TAC (R(2)=0.635+/-0.102, P<0.0001). Breast milk leptin, lysozyme and lactoferrin levels were identified as independent factors that significantly predict the concentration of TAC.

CONCLUSION

The identified enhancement of the antioxidant capacity of human milk by bio-active proteins that are lacking in commercial formula supports consideration of breast milk as ideal nutrition for preterm-born neonates.

Effects of synbiotic supplementation on total antioxidant capacity of human breastmilk

BACKGROUND AND OBJECTIVES

The aims of this study were to determine the effects of synbiotic (probiotic plus prebiotic) supplementation on total antioxidant capacity (TAC) and malondialdehyde (MDA) levels of human breastmilk.

SUBJECTS AND METHODS

In this randomized, double-blind, placebo-controlled trial, 80 lactating mothers were randomly divided into two groups to receive a daily supplement of synbiotic (n=40) or a placebo (n=40) for 30 days. Information on dietary intake was collected from lactating women using the 24-hour recall method for 3 days before and after supplementation. The TAC was measured by using a Randox (Crumlin, County Antrim, United Kingdom) assay, and the MDA level of breastmilk as thiobarbitaric acid complexes was measured by the fluorometry method. Data analysis was carried out using Nutritionist IV (Axxya Systems, Stafford, TX) and SPSS (SPSS, Inc., Chicago, IL).

RESULTS

The TAC of breastmilk increased significantly from 0.312±0.16 to 0.481±0.2 mmol/L in the supplemented group (p<0.039), whereas it decreased from 0.317±0.18 to 0.255±0.13 mmol/L in the placebo group (p>0.13). Although the MDA level decreased slightly from 1.62±0.69 to 1.6±0.95 μmol/L in the supplemented group, it increased significantly in the placebo group from 1.71±0.86 to 2.16±0.277 μmol/L after the experimental period (p<0.001). Also, maternal vitamin A, E, and C, zinc, and selenium intake did not change significantly in both groups during the study period. Moreover, no significant correlation was found between weight for age Z-score of infants and TAC and MDA levels in breastmilk.

CONCLUSIONS

Based on these results, synbiotic supplementation may have positive effects on the TAC and MDA levels in breastmilk; however, these findings require confirmation from future trials.