Antioxidant capacity of human milk and its association with vitamins A and E and fatty acid composition

Human Milk-The Biofluid That Nourishes Infants from the First Day of Life

Human milk is a biofluid with a unique composition among mammalian milks. Besides this milk's major components, its bioactive compounds, like hormones, immune factors, and oligosaccharides, are unique and important for infant growth and development. The best form of nutrition for term and preterm infants is the mother's own milk. However, in the absence of the mother's own milk, donor milk should be made available. Milk banks support neonatal intensive care units by providing preterm infants with human milk that generally has reasonable nutritive value for this sensitive population. However, neither mother's own milk nor donor milk has sufficient energy content for the growth of preterm babies, so adequate human milk supplementation is crucial for their progress. Due to the different characteristics of human breast milk, as well as ubiquitous environmental pollutants, such as microplastics, new methods are required for monitoring the quality and characteristics of human milk, which will lay a solid foundation for the further development and progress of human milk research.

The Impact of Linoleic Acid on Infant Health in the Absence or Presence of DHA in Infant Formulas

Both linoleic acid (LA) and α-linolenic acid (ALA) are essential dietary fatty acids, and a balanced dietary supply of these is of the utmost importance for health. In many countries across the globe, the LA level and LA/ALA ratio in breast milk (BM) are high. For infant formula (IF), the maximum LA level set by authorities (e.g., Codex or China) is 1400 mg LA/100 kcal ≈ 28% of total fatty acid (FA) ≈ 12.6% of energy. The aims of this study are: (1) to provide an overview of polyunsaturated fatty acid (PUFA) levels in BM across the world, and (2) to determine the health impact of different LA levels and LA/ALA ratios in IF by reviewing the published literature in the context of the current regulatory framework. The lipid composition of BM from mothers living in 31 different countries was determined based on a literature review. This review also includes data from infant studies (intervention/cohort) on nutritional needs regarding LA and ALA, safety, and biological effects. The impact of various LA/ALA ratios in IF on DHA status was assessed within the context of the current worldwide regulatory framework including China and the EU. Country averages of LA and ALA in BM range from 8.5-26.9% FA and 0.3-2.65% FA, respectively. The average BM LA level across the world, including mainland China, is below the maximum 28% FA, and no toxicological or long-term safety data are available on LA levels > 28% FA. Although recommended IF LA/ALA ratios range from 5:1 to 15:1, ratios closer to 5:1 seem to promote a higher endogenous synthesis of DHA. However, even those infants fed IF with more optimal LA/ALA ratios do not reach the DHA levels observed in breastfed infants, and the levels of DHA present are not sufficient to have positive effects on vision. Current evidence suggests that there is no benefit to going beyond the maximum LA level of 28% FA in IF. To achieve the DHA levels found in BM, the addition of DHA to IF is necessary, which is in line with regulations in China and the EU. Virtually all intervention studies investigating LA levels and safety were conducted in Western countries in the absence of added DHA. Therefore, well-designed intervention trials in infants across the globe are required to obtain clarity about optimal and safe levels of LA and LA/ALA ratios in IF.

Antioxidant Activity of Different Tissues from Rabbits Fed Dietary Bovine Colostrum Supplementation

Recent advances in animal nutrition have indicated that bovine colostrum (BC), due to its content of macronutrients, micronutrients and bioactive compounds, is an excellent health supplement. To the best of our knowledge, no studies on the effect of BC on antioxidant status have been performed in rabbits. This study aimed to investigate the effect of two BC concentrations on antioxidant status and gene expression of antioxidant enzymes in some tissues of rabbits. Thirty New Zealand White male rabbits were randomly divided into three experimental diets, containing 0% (CON), 2.5%, and 5% of BC (BC-2.5 and BC-5, respectively). The activity of antioxidant enzymes in plasma (catalase: CAT; glutathione peroxidase: GPx; superoxide dismutase: SOD), and the enzymes' gene expression in the liver and longissimus dorsi muscle, were determined. Results showed no significant differences, neither in plasma nor in tissues. A significant tissue-related effect has been observed regarding the mRNA levels of SOD and GPx, which were higher in the LD (p = 0.022) and liver (p = 0.001), respectively. Further studies, considering modifications of the length and dosage of dietary BC supplementation, are required to update the current state of knowledge in rabbits, as well as to fully understand the potential value of BC for possible application in farming use.

Shaping infant development from the inside out: Bioactive factors in human milk

Human breast milk is the optimal nutrition for all infants and is comprised of many bioactive and immunomodulatory components. The components in human milk, such as probiotics, human milk oligosaccharides (HMOs), extracellular vesicles, peptides, immunoglobulins, growth factors, cytokines, and vitamins, play a critical role in guiding neonatal development beyond somatic growth. In this review, we will describe the bioactive factors in human milk and discuss how these factors shape neonatal immunity, the intestinal microbiome, intestinal development, and more from the inside out.

Vitamin A Concentration in Human Milk: A Meta-Analysis

Humans require vitamin A (VA). However, pooled VA data in human milk is uncommon internationally and offers little support for dietary reference intake (DRIs) revision of infants under 6 months. As a result, we conducted a literature review and a meta-analysis to study VA concentration in breast milk throughout lactation across seven databases by August 2021. Observational or intervention studies involving nursing mothers between the ages of 18 and 45, with no recognized health concerns and who had full-term infants under 48 months were included. Studies in which retinol concentration was expressed as a mass concentration on a volume basis and determined using high-, ultra-, or ultra-fast performance liquid chromatography (HPLC, UPLC, or UFLC) were chosen. Finally, 76 papers involving 9171 samples published between 1985 and 2021 qualified for quantitative synthesis. Results from the random-effects model showed that the VA concentration of healthy term human milk decreased significantly as lactation progressed. VA (µg/L) with 95% CI at the colostrum, transitional, early mature and late mature stages being 920.7 (744.5, 1095.8), 523.7 (313.7, 733.6), 402.4 (342.5, 462.3) and 254.7 (223.7, 285.7), respectively (X2 = 71.36, p < 0.01). Subgroup analysis revealed no significant differences identified in VA concentration (µg/L) between Chinese and non-Chinese samples at each stage, being 1039.1 vs. 895.8 (p = 0.64), 505.7 vs. 542.2(p = 0.88), 408.4 vs. 401.2 (p = 0.92), 240.0 vs. 259.3 (p = 0.41). The findings have significant implications for the revision of DRIs for infants under six months.

Vitamin E concentration in breast milk in different periods of lactation: Meta-analysis

Objective

This study systematized information about vitamin E concentration in healthy breast milk during different stages of lactation in order to support the strategies of protecting postpartum women and infants.

Methods

Studies published before April 30th, 2021, which detected vitamin E concentration in breast milk of healthy women by High Performance Liquid Chromatography (HPLC) or Ultra High Performance Liquid Chromatographic (UHPLC), were evaluated. The databases of CNKI (Chinese), WanFang Data (Chinese), VIP (Chinese), PubMed, Cochrane Library, Web of Science and Embase were searched. The random effect models were used to conduct meta-analysis by the statistical software package Stata 14.0.

Results

In all 4,791 searched publications, 53 with full text were selected, which included 46 descriptive studies, 1 case-control study, 1 non-randomized controlled trial, and 5 randomized controlled trials. The pooled mean of vitamin E concentration was 10.57 mg α-TE/L (95%CI 8.94–12.20) in colostrum, 4.03 mg α-TE/L (95%CI 3.29–4.77) in transitional milk and 3.29 mg α-TE/L (95%CI 2.95–3.64) in mature milk. Subgroup analysis showed that vitamin E concentration of colostrum in Asian countries was lower than that in Western countries in colostrum and transitional milk.

Conclusions

Vitamin E concentration in breast milk decreased during lactation until the mature milk was produced. The vitamin E concentration of colostrum in Asian countries was evidently lower than that in Western countries. The vitamin E concentration in mature milk is similar in different regions. The concentration of vitamin E in breast milk started to be stable from about 2 to 3 weeks postpartum until 4 or 6 months postpartum, but it needs additional evidence to support.

Effect of convection and microwave heating on the retention of bioactive components in human milk

Bioactive substances are very important components of human milk (HM), especially for premature newborns. The effects of convection (CH) and microwave heating (MWH) at 62.5 and 66 °C, on the level of selected bioactive components of HM: lysozyme (LZ), lactoferrin (LF), secretory immunoglobulin A (sIgA), basal lipase (BL), cytokine TGF-2, vitamin C and total antioxidant capacity (TAC) was compared. Regardless of the used heating methods the TAC of HM, determined by TEAC and ORAC-FL assay, proved to be insensitive to temperature pasteurization, in contrary to BL. MWH in the conditions of 62.5 for 5 min and 66 °C for 3 min are ensuring microbiological safety with a higher retention of most of the tested active HM proteins compared to CH. Only in the case of LZ the MWH had a more degradative effect on its concentration. Controlled conditions of MWH preserve the bioactive components of the HM better than CH.

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.

Immunological components and antioxidant activity in human milk processed by different high pressure-thermal treatments at low initial temperature and flash holding times

The effect of high pressure thermal (HPT) processing on the immunoglobulin (IgM, IgA and IgG), and cytokine content (IL-6, IL-8, IL-10, and TNF-α), and antioxidant activity of human milk was analyzed after the application of different treatments between 200, and 800 MPa at low initial temperatures (between -15, and 50 °C) and for 1 s (flash treatments). Low pressures intensities did not induce changes in Igs while at 800 MPa, all combinations reduced the control levels. IL-6 and IL-10 were not affected by any of the treatments applied while IL-8 and TNF-α were reduced at treatments which combined temperatures at 50 °C. In general antioxidant activity was not affected at the processing conditions chosen. The flash HPT treatment applied at 600 MPa and at 0 °C could be the best choice to preserve immunological parameters and the antioxidant activity of human milk.

Glycemic Response and Bioactive Properties of Gluten-Free Bread with Yoghurt or Curd-Cheese Addition

The influence of flour replacement by yogurt or curd-cheese additions (from 10% to 20%, w/w) on the glycemic response and bioactivity improvements of gluten-free bread was evaluated. Starch digestibility, measured by an in vitro digestion model, was applied to determine the effect on starch fractions. The bread glycemic index was calculated. Bread antioxidant capacity (2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and ferric-ion-reducing antioxidant power (FRAP) methods) and total phenolic compounds were assessed. Anti-inflammatory properties according to enzymatic matrix metalloproteinase (MMP)-9 inhibitory activity were also studied. Considering the higher level of both dairy products tested (20%, w/w) and comparing with control bread results, a reduction of around 35% in the glycemic response of curd cheese bread was achieved, resulting in intermediate index level (glycemic index (GI) 55-69), with yogurt bread still showing a high glycemic index (GI > 70). In terms of bread bioactivity, curd cheese bread expressed better reducing power effects, whereas yogurt bread showed more effective radical-scavenging capacity. An increase in bread phenolic compounds by yogurt (55.3%) and curd cheese (73.0%) additions (at 20%) were also registered. MMP-9 inhibition activity was higher in the dairy bread than in control bread, suggesting an improvement in terms of anti-inflammatory properties. The supplementation of the gluten-free bread by yogurt or curd cheese was shown to be a promising strategy to reduce the glycemic response and to improve the bioactive properties of the bread, that which can contribute to preventive diets of celiac patients and irritable bowel syndrome individuals.

The Mode of Grass Supply to Dairy Cows Impacts on Fatty Acid and Antioxidant Profile of Milk

The optimization of milk production includes a rational use of forages, respect for the environment and offers the best quality to consumers. Milk production based on grass and forages produces healthier milk and it is widely spread throughout the Atlantic arc to maximize milk yield per hectare. However, the mode of offering the grass can have a major influence on milk composition. The aim of this study was to evaluate the effect of grass supply mode (grazing, zero-grazing or ensiling) on dairy cows’ performance, with particular reference to fatty acids and fat-soluble antioxidants concentration. A three by three Latin square experiment was performed with 18 dairy cows. Experimental treatments consisted of exclusive feeding with grass silage and zero-grazing, both offered ad libitum indoors, or grazing for 24 h. The results showed that grazing cows had a higher dry matter intake and greater milk yield than cows feeding on grass silage and zero-grazing, as well as higher concentrations of protein, lactose, nonfat-solids and urea in milk than housed cows. Milk fat from grazing cows had a higher proportion of unsaturated fatty acids than from cows feeding on grass silage and zero-grazing, with significant differences in the proportion of vaccenic and rumenic acids. The 18:1 trans-11 to 18:1 trans-10 ratio is proposed as biomarker to identify the milk produced from the management system of grazing cattle. Milk from grazing cows had a greater proportion of lutein than cows eating grass silage, with the zero-grazing system having intermediate values. In conclusion, the mode of grass supply affects fatty acid and antioxidant profiles of milk.

Dietary Lipid Intake Influences the Alpha-tocopherol Levels in Human Milk

OBJECTIVE

Dietary lipid intake is associated with serum alpha-tocopherol levels; however, its impact on human milk is unknown. The objective of this study was to evaluate the relationship between maternal intake of vitamin E, lipids, and fatty acids and the concentration of alpha-tocopherol in human milk.

METHODS

We conducted a longitudinal observational study, including 143 lactating women on 7, 30, and 90 days postpartum. Dietary intake was collected using 24-hour recall. On day 90, a human milk sample was collected and analyzed for alpha-tocopherol concentration. The prevalence of inadequate vitamin E intake was determined by the Estimated Average Requirement (16 mg/day), and the alpha-tocopherol concentration was analyzed by high-performance liquid chromatography.

RESULTS

Dietary intake of vitamin E was associated with the intake of lipids (r = 0.237, P = 0.004) and fatty acids (P < 0.05), and 100% of the participants had inadequate vitamin intake. Mean alpha-tocopherol concentration in the human milk samples was 7.11 (standard deviation 3.95) μmol/L and was correlated with lipid (r = 0.201, P = 0.042) and polyunsaturated fatty acid intake (r = 0.235, P = 0.017). Higher vitamin E levels were found in participants with the highest quartile of polyunsaturated fatty acid intake.

CONCLUSIONS

Alpha-tocopherol concentration was associated with the dietary intake of lipids and fatty acids, demonstrating that its bioavailability is associated with fats in the mammary gland. These results suggest development of appropriate strategies to increase the levels of vitamin E in breast milk that may help to prevent and treat vitamin E deficiency.

Human milk fatty acid profile across lactational stages after term and preterm delivery: A pooled data analysis

BACKGROUND

Lipids in human milk (HM) provide the majority of energy for developing infants, as well as crucial essential fatty acids (FA). The FA composition of HM is highly variable and influenced by multiple factors. We sought to increase understanding of the variation in HMFA profiles and their development over the course of lactation, and after term and preterm delivery, using a pooled data analysis.

OBJECTIVE

To review the literature and perform a pooled data analysis to qualitatively describe an extensive FA profile (36 FAs) in term and preterm colostrum, transitional - and mature milk up to 60 days postpartum.

DESIGN

A Medline search was conducted for HMFA profile data following term or preterm delivery. The search was confined to English language papers published between January 1980 and August 2018. Studies reporting original data, extensive FA profiles in HM from healthy mothers were included. Weighted least squares (WLS) means were calculated from the pooled data using random or fixed effect models.

RESULTS

Our pooled data analysis included data from 55 studies worldwide, for a total of 4374 term milk samples and 1017 preterm milk samples, providing WLS means for 36 FAs. Patterns in both term and preterm milk were apparent throughout lactation for some FAs: The most abundant FAs (palmitic, linoleic and oleic acid) remained stable over time, whereas several long-chain polyunsaturated FAs (including ARA and DHA) seemed to decrease and short- and medium-chain FAs increased over time.

CONCLUSIONS

High heterogeneity between individual studies was observed for the reported levels of some FAs, whereas other FAs were remarkably consistent between studies. Our pooled data suggests that specific FA categories fluctuate according to distinct patterns over the course of lactation; many of these patterns are comparable between term and preterm milk.

Fatty acids of human milk - a review

The composition of human milk is the result of the evolution of mammals over millions of years. Among the most important components of milk are fatty acids. Approximately 85% are saturated and monounsaturated fatty acids - the rest are polyunsaturated one. Their role is to provide energy and immunity and to serve as buildings blocks, as well as assisting the hormonal system and the metabolism of fats, carbohydrates and proteins. The structural differences between fatty acids determine their biodiversity and give them particular physiological importance. Correct development of the nervous system, retina and other structures depend on an adequate supply of both these fatty acids during intrauterine development and in the newborn and infant stages. The fats present in milk form milk fat globules - structures that do not appear in milk formula prepared using vegetable oils. Apart from the mother's diet, other sources of fatty acids are endogenous biosynthesis in the mammary gland and the fat deposits from which the fatty acids are released. Evolution of the mother's body has also created adaptive mechanisms that adjust the amount of fatty acids in milk to the state of health and needs of the child. These mechanisms go some way to creating a buffer with regard to dietary shortages experienced by pregnant/breastfeeding women, and optimalise the composition of milk fatty acids depending on the age of the pregnant woman, the birth weight of the infant and the efficiency of the placenta during pregnancy.

Hygienic-sanitary quality and effect of freezing time and temperature on total antioxidant capacity of human milk

Abstract Knowledge of the hygienic-sanitary quality of raw human milk helps to establish the best storage conditions for the preservation of its nutritional and functional components. Therefore, this study aimed to evaluate the hygienic-sanitary quality of human milk extracted at the mothers’ homes, and to analyze the effect of freezing time and temperature on the milk’s total antioxidant capacity. Milk of five mothers was evaluated individually for Staphylococcus aureus, total aerobic mesophilic counts, mold and yeasts, total and thermotolerant coliforms. The milk pool was stored at -8 °C, -18 °C and -40 °C for 2, 4, 8 and 15 days and analyzed for the total antioxidant capacity by the 2,2-diphenyl-1-picrylhydrazyl free radical and 2,2-azino 3-ethylbenzothiazoline-6-sulfonic acid scavenging methods. The microbiological analyses of the raw human milk samples indicated counts of all the studied microorganisms above the safe limits. Related to the effect of freezing time and temperature on total antioxidant capacity, it was concluded that, regardless of the freezing temperature, a significant reduction occurred on total antioxidant capacity over time and that the lower the storage temperature, the greater its total antioxidant activity.

The effects of storage conditions on long-chain polyunsaturated fatty acids, lipid mediators, and antioxidants in donor human milk - A review

Donor human milk (DHM) is the recommended alternative, if maternal milk is unavailable. However, current human milk banking practices may negatively affect the nutritional quality of DHM. This review summarises the effects of these practices on polyunsaturated fatty acids, lipid mediators and antioxidants of human milk. Overall, there is considerable variation in the reported effects, and further research is needed, particularly with lipid mediators and antioxidants. However, to preserve nutritional quality, DHM should be protected from light exposure and storage at 4 °C minimised, to prevent decreases in vitamin C and endocannabinoids and increases in free fatty acids and lipid peroxidation products. Storage at -20 °C prior to pasteurisation should also be minimised, to prevent free fatty increases and total fat and endocannabinoid decreases. Storage ≤-70 °C is preferable wherever possible, although post-pasteurisation storage at -20 °C for three months appears safe for free fatty acids, lipid peroxidation products, and total fat content.

Factors Associated with Increased Alpha-Tocopherol Content in Milk in Response to Maternal Supplementation with 800 IU of Vitamin E

Background: Vitamin E supplementation might represent an efficient strategy to increase the vitamin E content in milk. The present study aimed to evaluate the impact of supplementation with 800 IU RRR-alpha-tocopherol on the alpha-tocopherol content of milk and the factors associated with the increase in vitamin E. Methods: Randomized clinical trial with 79 lactating women from Brazil, who were assigned to the control group, or to the supplemented group (800 IU of RRR-alpha-tocopherol). Milk and serum were collected between 30 and 90 days after delivery (collection 1), and on the next day (collection 2). Alpha-tocopherol was analyzed using high-performance liquid chromatography. Results: In the supplemented group, the alpha-tocopherol content in serum and milk increased after supplementation (p < 0.001). In the multivariate analysis, only alpha-tocopherol in milk (collection 1) was associated with the level of this vitamin in milk after supplementation (β = 0.927, p < 0.001), and binary logistic regression showed that the dietary intake was the only determinant for the greater effect of supplementation in milk. Conclusion: The pre-existing vitamin level in milk and diet are determinants for the efficacy of supplementation in milk, suggesting that in populations with vitamin E deficiency, high-dose supplementation can be used to restore its level in milk.

Antioxidant properties of Milk and dairy products: a comprehensive review of the current knowledge

Milk and dairy products are integral part of human nutrition and they are considered as the carriers of higher biological value proteins, calcium, essential fatty acids, amino acids, fat, water soluble vitamins and several bioactive compounds that are highly significant for several biochemical and physiological functions. In recent years, foods containing natural antioxidants are becoming popular all over the world as antioxidants can neutralize and scavenge the free radicals and their harmful effects, which are continuously produced in the biological body. Uncontrolled free radicals activity can lead to oxidative stresses, which have been implicated in breakdown of vital biochemical compounds such as lipids, protein, DNA which may lead to diabetes, accelerated ageing, carcinogenesis and cardiovascular diseases. Antioxidant capacity of milk and milk products is mainly due to sulfur containing amino acids, such as cysteine, phosphate, vitamins A, E, carotenoids, zinc, selenium, enzyme systems, superoxide dismutase, catalase, glutathione peroxidase, milk oligosaccharides and peptides that are produced during fermentation and cheese ripening. Antioxidant activity of milk and dairy products can be enhanced by phytochemicals supplementation while fermented dairy products have been reported contained higher antioxidant capacity as compared to the non-fermented dairy products. Literature review has shown that milk and dairy products have antioxidant capacity, however, information regarding the antioxidant capacity of milk and dairy products has not been previously compiled. This review briefly describes the nutritional and antioxidant capacity of milk and dairy products.

Micronutrient content and antioxidant enzyme activities in human breast milk

Breast milk contains micronutrients that function as cofactors of antioxidant enzymes. High concentrations of iron (Fe) and copper (Cu) can increase the production of reactive oxygen species (ROS). This study aimed to assess the relationship between the activity of antioxidant enzymes (superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST)) and the concentration of the micronutrients Fe, Cu and zinc (Zn) in breast milk. Breast milk samples were collected from 108 mothers (7-10 days postpartum, transitional milk). The samples were grouped into three groups according to the number of pregnancies (one, two and three or more pregnancies), also grouped according to the body mass index (BMI) suggested by the World Health Organization (WHO) in underweight, normal weight, overweight and obese. Breast milk Fe, Cu and Zn concentrations were determined by atomic absorption spectrophotometry and the activity of the antioxidant enzymes was determined by spectrophotometry. An increase in GPx, SOD and GST activities in relation to the number of pregnancies was found (p = 0.05, p = 0.04 and p < 0.01, respectively). An inverse relationship between GST activity and BMI was found (p = 0.05). A positive correlation was observed between Cu and Zn concentrations (r = 0.52, p < 0.05). A negative correlation was found between Cu concentration and catalase activity (r = -0.22, p < 0.05); Fe content was negatively correlated with GPx and GST activities (r = -0.32, r = -0.22, respectively, p < 0.05). The activities of antioxidant enzymes (GPx, SOD and GST) may be affected by the number of pregnancies and contribute to prevent oxidation of nutritional molecules in breast milk.

Human Milk Lipidomics: Current Techniques and Methodologies

Human milk contains a complex combination of lipids, proteins, carbohydrates, and minerals, which are essential for infant growth and development. While the lipid portion constitutes only 5% of the total human milk composition, it accounts for over 50% of the infant’s daily energy intake. Human milk lipids vary throughout a feed, day, and through different stages of lactation, resulting in difficulties in sampling standardization and, like blood, human milk is bioactive containing endogenous lipases, therefore appropriate storage is critical in order to prevent lipolysis. Suitable sample preparation, often not described in studies, must also be chosen to achieve the aims of the study. Gas chromatography methods have classically been carried out to investigate the fatty acid composition of human milk lipids, but with the advancement of other chromatographic techniques, such as liquid and supercritical fluid chromatography, as well as mass spectrometry, intact lipids can also be characterized. Despite the known importance, concise and comprehensive analysis of the human milk lipidome is limited, with gaps existing in all areas of human milk lipidomics, discussed in this review. With appropriate methodology and instrumentation, further understanding of the human milk lipidome and the influence it has on infant outcomes can be achieved.

RRR-α-Tocopherol Is the Predominant Stereoisomer of α-Tocopherol in Human Milk

BACKGROUND

The naturally occurring α-tocopherol (α-T) stereoisomer, RRR-α-tocopherol (RRR-α-T), is known to be more bioactive than all-rac-α-tocopherol (all-rac-α-T), a synthetic racemic mixture of 8 stereoisomers. There is widespread use of all-rac-α-T in maternal supplements.

OBJECTIVE

The aim of the study was to thoroughly describe the α-T stereoisomer profile of human milk.

METHODS

We measured the α-T stereoisomer profile in milk from 2 cohorts of women: a cohort of 121 women who provided milk on days 30 and 60 of lactation (study 1) and a separate cohort of 51 women who provided milk on days 10, 21, 71, and 120 of lactation (study 2).

RESULTS

RRR-α-T was the predominant stereoisomer (P < 0.0001) in all samples in both studies despite a large intrasubject range in total α-T (0.7-22 μg/mL). On average, RRR-α-T comprised 73-76% of total α-T, but average values for the synthetic stereoisomers were RRS, 8-14%; RSR, 6-8%; RSS, 5-6%; and the sum of 2S stereoisomers (Σ2S), 3-5%. Despite the predominance of RRR-α-T, the sum of the synthetic stereoisomers comprised as much as 48% of total α-T. We calculated the ratio of RRR to the sum of the synthetic 2R (RRS + RSR + RSS) stereoisomers (s2R) to assess the degree to which RRR is favored in milk. Consistent with discrimination among 2R stereoisomers in mammary tissue, RRR/s2R values ranged from 2.8 to 3.6, as opposed to the expected ratio of 0.33 if there was no discrimination. However, the RRR to s2R ratio did not correlate with milk α-T concentration, but both components of the ratio did.

CONCLUSIONS

RRR-α-T is the predominant stereoisomer in human milk, concentrations of synthetic 2R stereoisomers were notable, and the relation between milk total α-T and stereoisomer profile is complex. Due to the wide range found in milk α-T stereoisomer profile, investigation into its impact on α-T status and functional outcomes in breastfed infants is warranted.

Human Milk Nutrient Composition in the United States: Current Knowledge, Challenges, and Research Needs

Human milk is considered to be the ideal food for infants. Accurate, representative, and up-to-date nutrient composition data of human milk are crucial for the management of infant feeding, assessment of infant and maternal nutritional needs, and as a guide for developing infant formula. Currently in the United States, the nutrient profiles of human milk can be found in the USDA National Nutrient Database for Standard Reference, and in books or review articles. Nonetheless, these resources all suffer major drawbacks, such as being outdated, incomplete profiles, limited sources of data, and uncertain data quality. Furthermore, no nutrient profile was developed specifically for the US population. The purposes of this review were to summarize the current knowledge of human milk nutrient composition from studies conducted in the United States and Canada, and to identify the knowledge gaps and research needs. The literature review was conducted to cover the years 1980-2017, and 28 research papers were found containing original data on macronutrients and micronutrients. Most of these 28 studies were published before 1990 and mainly examined samples from small groups of generally healthy lactating women. The experimental designs, including sampling, storage, and analytic methods, varied substantially between the different studies. Data of several components from these 28 studies showed some consistency for 1-6 mo postpartum, especially for protein, fat, lactose, energy, and certain minerals (e.g., calcium). The data for 7-12 mo postpartum and for other nutrients are very scarce. Comprehensive studies are required to provide current and complete nutrient information on human milk in the United States.

Micronutrients in Human Milk: Analytical Methods

Exclusive breastfeeding is recommended by the WHO for the first 6 mo of life because human milk protects against gastrointestinal infections and supplies balanced and adequate nutrient contents to the infant. However, reliable data on micronutrient concentrations in human milk are sparse, especially because some micronutrients are affected by maternal diet. Microbiological and competitive protein-binding assays, nuclear magnetic resonance or inductively coupled plasma spectroscopy, and chromatographic analyses are among the methods that have been applied to human-milk micronutrient analysis. However, the validation or evaluation of analytical methods in terms of their suitability for the complex human-milk matrix has been commonly ignored in reports, even though the human-milk matrix differs vastly from blood, plasma, or urine matrixes. Thus, information on the validity, accuracy, and sensitivity of the methods is essential for the estimation of infant and maternal intake requirements to support and maintain adequate milk micronutrient concentrations for healthy infant growth and development. In this review, we summarize current knowledge on methods used for analyzing water- and fat-soluble vitamins as well as iron, copper, zinc, iodine, and selenium in human milk and their different forms in milk; the tools available for quality control and assurance; and guidance for preanalytical considerations. Finally, we recommend preferred methodologic approaches for analysis of specific milk micronutrients.

Phytochemicals in Human Milk and Their Potential Antioxidative Protection

Diets contain secondary plant metabolites commonly referred to as phytochemicals. Many of them are believed to impact human health through various mechanisms, including protection against oxidative stress and inflammation, and decreased risks of developing chronic diseases. For mothers and other people, phytochemical intake occurs through the consumption of foods such as fruits, vegetables, and grains. Research has shown that some these phytochemicals are present in the mother’s milk and can contribute to its oxidative stability. For infants, human milk (HM) represents the primary and preferred source of nutrition because it is a complete food. Studies have reported that the benefit provided by HM goes beyond basic nutrition. It can, for example, reduce oxidative stress in infants, thereby reducing the risk of lung and intestinal diseases in infants. This paper summarizes the phytochemicals present in HM and their potential contribution to infant health.

Relation between polyphenols, malondialdehyde, antioxidant capacity, lactate dehydrogenase and toxic elements in human colostrum milk

The present study investigated the interrelationships between the concentration of total polyphenols (TP), malondialdehyde (MDA), total antioxidant capacity (TAC), lactate dehydrogenase activity (LDH) and content of toxic elements (Al, As, Cd, Ni, Pb) in human colostrum milk (n = 75), and further assessed their potential association with maternal lifestyle characteristics. As and Cd were always below detection limits while Al, Ni and Pb were found at the level of 89.7, 6.2 and 1.3 μg L^-1, respectively. Concentrations of TP and MDA, in the studied group were 46.91 ± 21.25 mg GAE L^-1 and 0.66 ± 0.27 nmol mL^-1, respectively, and were inversely correlated (Rs = -0.32; p < 0.01). TP and TAC increased significantly with maternal consumption of vegetables (Rs = 0.25 and Rs = 0.37, respectively; p < 0.05). Concentration of Al was positively correlated with MDA (Rs = 0.21; p < 0.01) and negatively with TP (Rs = -0.28; p < 0.01). Positive correlation was also found between Pb and MDA (Rs = 0.32; p < 0.01). No association with place of living (urban/rural), women's age and former smoking were found for any studied milk parameter. The results add to the general understanding of factors influencing redox balance in milk and potentially affecting its quality.

Concentrations of Carotenoids and Tocopherols in Breast Milk from Urban Chinese Mothers and Their Associations with Maternal Characteristics: A Cross-Sectional Study

Milk composition remains the best estimate of infant requirements. The aims of this study were to quantify carotenoids and tocopherols in human milk from healthy Chinese mothers, and to explore their associations with lactation stage, region, socio-economic and obstetric characteristics, and dietary intake. Human milk was obtained from 509 healthy mothers, and concentrations of carotenoids and tocopherols were analyzed by Ultra High Performance Liquid Chromatography. The mothers’ socio-economic and obstetric characteristics and dietary intake through a single 24-h dietary recall were evaluated. The median concentrations (μg/100 mL) of each component of 0–4 days, 5–11 days, 12–30 days, 31–60 days, 61–120 days, and 121–240 days postpartum were respectively as follows: β-carotene 8.0, 2.8, 2.1, 1.7, 1.9, 1.8; β-cryptoxanthin 6.2, 3.4, 2.4, 1.7, 1.8, 2.1; lutein 5.7, 7.0, 2.2, 2.9, 2.8, 3.7; lycopene 6.3, 2.5, 1.8, 1.4, 1.4, 1.5; zeaxanthin 1.0, 1.4, 0.8, 0.8, 1.0, 1.1; α-tocopherol 645, 382, 239, 206, 212, 211; γ-tocopherol 68, 63, 70, 73, 68, 88. The levels of those components varied significantly among different lactation stages and presented regional differences. Associations of carotenoid contents with maternal education, delivery mode, and present body mass index were found in multivariate analyses. These results suggested that lactation stage, region, and socio-economic and obstetric factors were associated with human milk concentrations of carotenoids and tocopherols in healthy Chinese mothers.

Innate Immunity and Breast Milk

Human milk is a dynamic source of nutrients and bioactive factors; unique in providing for the human infant's optimal growth and development. The growing infant's immune system has a number of developmental immune deficiencies placing the infant at increased risk of infection. This review focuses on how human milk directly contributes to the infant's innate immunity. Remarkable new findings clarify the multifunctional nature of human milk bioactive components. New research techniques have expanded our understanding of the potential for human milk's effect on the infant that will never be possible with milk formulas. Human milk microbiome directly shapes the infant's intestinal microbiome, while the human milk oligosaccharides drive the growth of these microbes within the gut. New techniques such as genomics, metabolomics, proteomics, and glycomics are being used to describe this symbiotic relationship. An expanded role for antimicrobial proteins/peptides within human milk in innate immune protection is described. The unique milieu of enhanced immune protection with diminished inflammation results from a complex interaction of anti-inflammatory and antioxidative factors provided by human milk to the intestine. New data support the concept of mucosal-associated lymphoid tissue and its contribution to the cellular content of human milk. Human milk stem cells (hMSCs) have recently been discovered. Their direct role in the infant for repair and regeneration is being investigated. The existence of these hMSCs could prove to be an easily harvested source of multilineage stem cells for the study of cancer and tissue regeneration. As the infant's gastrointestinal tract and immune system develop, there is a comparable transition in human milk over time to provide fewer immune factors and more calories and nutrients for growth. Each of these new findings opens the door to future studies of human milk and its effect on the innate immune system and the developing infant.

Retinol, α-tocopherol, and selected minerals in breast milk of lactating women with full-term infants in South Korea

BACKGROUND/OBJECTIVES

This study was performed to measure fat-soluble vitamins and minerals in breast milk of Korean lactating mothers who exclusively breastfed their babies.

SUBJECTS/METHODS

Breast milk samples were collected from 334 mothers. Concentrations of retinol and α-tocopherol were analyzed by high performance liquid chromatography ultraviolet spectrometry while concentrations of minerals were measured by inductively coupled plasma optical emission spectrometry.

RESULTS

Retinol and α-tocopherol contents of breast milk were 39.58 ± 19.64 µg/dL and 0.23 ± 0.13 mg/dL, respectively. Average sodium, potassium, calcium, phosphorus, and magnesium levels in breast milk were 11.11 ± 5.16, 38.56 ± 9.01, 27.87 ± 6.10, 13.56 ± 3.30, and 3.05 ± 0.65 mg/dL, respectively. Contents of trace elements such as iron, zinc, copper, and manganese were 40.26 ± 46.21, 98.40 ± 62.47, 24.09 ± 9.03, and 0.90 ± 1.63 µg/dL, respectively. Fat-soluble vitamin concentration was positively correlated with total fat in milk samples, but no significant differences were observed in levels of retinol, α-tocopherol, or minerals based on whether or not lactating women were taking dietary supplements.

CONCLUSIONS

Micronutrient contents of breast milk samples from Korean lactating women were comparable to those of other nations. Retinol and α-tocopherol levels were correlated and also with total fat in breast milk.

Retinol and α-Tocopherol in the Breast Milk of Women after a High-Risk Pregnancy

BACKGROUND

There is scant information about whether, after a high-risk pregnancy, breast milk provides enough vitamins for assuring satisfactory bodily reserves in newborns.

OBJECTIVE

To comparatively evaluate, in women with high-risk and normal pregnancy, the concentration of retinol and α-tocopherol in breast milk.

METHODS

This cross-sectional, analytical study was evaluated with reverse-phase high-performance liquid chromatography (HPLC). Informed consent was signed by 95 mothers with a high-risk pregnancy and 32 mothers with a normal pregnancy. From the mothers with a high-risk pregnancy were obtained: 23 samples of colostrum, 24 of transitional milk, and 48 of mature milk. From the normal pregnancy group, 32 mature milk samples were collected. Pregestational Body Mass Index (BMI) and the gestational weight gain were noted. Models of logistic regression were constructed to identify the variables related to a low concentration of either retinol or α-tocopherol in breast milk.

RESULTS

The concentration of retinol and α-tocopherol in mature milk was 60 (interquartile range (IQR), 41-90) and 276 (103-450) μg/dL, respectively, for the high-risk pregnancy group, and 76 (65-91) and 673 (454-866) µg/dL, respectively, for the normal pregnancy group (p = 0.001). The concentration of retinol and α-tocopherol was similar in the subgroups of mothers with different disorders during gestation. A clear correlation was found between a greater pregestational weight and a lower concentration of retinol (Rho = -0.280, p = 0.006), and between α-tocopherol and retinol in all cases (Rho = 0.463, p = 0.001). Among women having a high-risk pregnancy, those delivering prematurely rather than carrying their pregnancy to term had a reduced concentration of retinol (54 (37-78) vs. 70 (49-106) µg/dL; p = 0.002) and a tendency to a lower concentration of α-tocopherol in breast milk (185 (75-410) vs. 339 (160-500) µg/dL; p = 0.053). Compared to mothers with a normal pregnancy, those with a high-risk pregnancy (whether carried to term or ending in preterm delivery) exhibited a reduced concentration of retinol in mature milk (p = 0.003), as well as a tendency to a lower concentration of α-tocopherol (p = 0.054).

CONCLUSION

Even though the women in the high-risk pregnancy group showed a deficiency of vitamins A and E in their breast milk, the unique biological benefits of this milk justify the promotion of breast feeding as the optimal method of nourishing neonates and infants. In these cases, it should be recommended that the woman increase her consumption of certain nutrients during pregnancy. Additionally, after childbirth mothers should consider the use of supplements to produce milk of adequate quality and thus meet the needs of the baby and prevent any deficiency in micronutrients.

Effect of maternal supplementation with vitamin E on the concentration of α-tocopherol in colostrum

OBJECTIVE

To evaluate the effect of maternal supplementation with vitamin E on the concentration of α-tocopherol in colostrum and its supply to the newborn.

METHOD

This randomized clinical trial enrolled 99 healthy adult pregnant women; of these, 39 were assigned to the control group and 60 to the supplemented group. After an overnight fast, 5mL of blood and 2mL of colostrum were collected. After the first sampling (0h milk), the supplemented group received 400IU of supplementary vitamin E. Another 2mL milk aliquot was collected in both groups 24h after supplementation (24h milk). The samples were analyzed by high-performance liquid chromatography. The α-tocopherol content provided by colostrum was calculated by considering a daily intake of 396mL of milk and comparing the resulting value to the recommended daily intake for infants aged 0-6 months (4mg/day).

RESULTS

The initial mean concentration of α-tocopherol in colostrum was 1509.3±793.7μg/dL in the control group and 1452.9±808.6μg/dL in the supplemented group. After 24h, the mean α-tocopherol concentration was 1650.6±968.7μg/dL in the control group (p>0.05) and 2346.9±1203.2μg/dL in the supplemented group (p<0.001), increasing the vitamin E supply to the newborn to 9.3mg/day. Initially, 18 women in the supplemented group provided colostrum α-tocopherol contents below 4mg/day; after supplementation only six continued to provide less than the recommended amount.

CONCLUSION

Maternal vitamin E supplementation increases the supply of the vitamin to the infant by providing more than twice the Recommended Daily Intake.

Association between maternal vitamin E status and alpha-tocopherol levels in the newborn and colostrum

Vitamin E is important because of its antioxidant activity in situations of oxidative stress, especially postnatally. Hence, the objective was to verify whether maternal alpha-tocopherol level is associated with the alpha-tocopherol levels of the newborn and colostrum. This is a cross-sectional study of 58 women and their term newborns from a public hospital. Blood and colostrum were collected to measure alpha-tocopherol levels by high-performance liquid chromatography. Mothers with serum alpha-tocopherol levels <16.2 mmol L(-1) and newborns <11.6 mmol L(-1) were indicative of deficiency or low levels. Mothers were divided into two groups: <16.2 mmol L(-1) and those with levels ≥16.2 mmol L(-1) . The mean (95% confidence interval) serum alpha-tocopherol levels of mothers, umbilical cords and colostrum were 28 (24-32), 6 (5-8) and 39 mmol L(-1) (32-45), respectively (P < 0.001); 19% of the women and 90% of the newborns had low alpha-tocopherol levels. Maternal alpha-tocopherol level was associated with that of the umbilical cord. Newborns from mothers at risk of deficiency had low alpha-tocopherol levels (P < 0.001). Colostrum levels of vitamin E were not influenced by maternal serum. Maternal deficiency influenced the vitamin E level of the umbilical cord but does not in the colostrum, evidencing distinct transfer mechanisms via the mammary gland.

Retinol and α-tocopherol in human milk and their relationship with dietary intake during lactation

Human milk is considered as an optimal nutrition source for neonates, and vitamins A and E improve oxidative stress in offspring through breast milk.

Immediate breastfeeding and skin-to-skin contact during cesarean section decreases maternal oxidative stress, a prospective randomized case-controlled study

OBJECTIVE

Immediate skin-to-skin contact (ISSC) and early breastfeeding are recommended for the wellbeing of the neonate. In this study, we aimed to evaluate the effect of ISSC and early breastfeeding on maternal oxidative stress and postoperative pain.

METHODS

A total of 90 patients were randomized into two groups based on the timing of skin-to-skin contact and breastfeeding. Group 1 (n = 45) was provided ISSC and breastfeeding in the operating room during the cesarean section (C/S). Group 2 (n = 45) breastfed their babies 1 h after the C/S. As markers of oxidative stress, maternal serum levels of total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress indices (OSI) were evaluated. Maternal oxytocin levels and the relation between these parameters and postoperative pain were also evaluated.

RESULTS

The postoperative TAS levels were significantly higher, whereas TOS and OSI levels were lower in Group 1 than Group 2. Negative correlations between oxytocin level and postoperative TOS and OSI were observed, as was a positive correlation between oxytocin level and postoperative TAS.

CONCLUSIONS

The effect of ISSC and early breastfeeding on mothers was documented for the first time in this study. Our results demonstrated ISSC and early breastfeeding during C/S reduce maternal oxidative stress.

Multiplatform characterization of dynamic changes in breast milk during lactation

The multicomponent analysis of human breast milk (BM) by metabolic profiling is a new area of study applied to determining milk composition, and is capable of associating BM composition with maternal characteristics, and subsequent infant health outcomes. A multiplatform approach combining HPLC‐MS and ultra‐performance LC‐MS, GC‐MS, CE‐MS, and ¹H NMR spectroscopy was used to comprehensively characterize metabolic profiles from seventy BM samples. A total of 710 metabolites spanning multiple molecular classes were defined. The utility of the individual and combined analytical platforms was explored in relation to numbers of metabolites identified, as well as the reproducibility of the methods. The greatest number of metabolites was identified by the single phase HPLC‐MS method, while CE‐MS uniquely profiled amino acids in detail and NMR was the most reproducible, whereas GC‐MS targeted volatile compounds and short chain fatty acids. Dynamic changes in BM composition were characterized over the first 3 months of lactation. Metabolites identified as altering in abundance over lactation included fucose, di‐ and triacylglycerols, and short chain fatty acids, known to be important for infant immunological, neurological, and gastrointestinal development, as well as being an important source of energy. This extensive metabolic coverage of the dynamic BM metabolome provides a baseline for investigating the impact of maternal characteristics, as well as establishing the impact of environmental and dietary factors on the composition of BM, with a focus on the downstream health consequences this may have for infants.

Effect of vitamin C and E supplementation on total antioxidant content of human breastmilk and infant urine

OBJECTIVES

After delivery and birth, mothers and neonates are exposed to oxidative stress. The present study examined the effect of supplementation of the diet of breastfeeding mothers with vitamin C and E to improve the antioxidant content of breastmilk and evidence of antioxidant activity in infant urine.

SUBJECTS AND METHODS

The subjects were 60 healthy lactating breastfeeding mothers and their infants 1-6 months of age. They were randomly allocated to a control group (n=30) consuming a free diet or an experimental group (n=30) consuming a free diet supplemented each day with effervescent tablets of vitamin C (500 mg) and chewable tablets of vitamin E (100 IU). After 30 days, the total antioxidant content of the mothers' breastmilk and evidence of antioxidant activity in the infants' urine were measured by the ferric reducing/antioxidant power assay. The free radical scavenging activity of the urine samples was measured by the α,α-diphenyl-β-picrylhydrazyl method. Differences pre- and postintervention were compared within and between the groups.

RESULTS

Significantly higher levels of antioxidants in the breastmilk (610±295.5 to 716±237.5 μmol/L) and infant urine (43.2±21.8 to 75.0±49.2 μmol/mg creatinine) were observed in the experimental group over the control group (p<0.05). A significant increase in evidence of free radical scavenging in infant urine was observed in the experimental group after 30 days of supplementation by mothers (p<0.05).

CONCLUSIONS

Consumption of vitamin C and E supplements appears to have a positive effect on total antioxidant content of breastmilk and evidence of antioxidant activity in infant urine.

Vitamin E concentration in human milk and associated factors: a literature review

OBJECTIVE

To systematize information about vitamin E concentration in human milk and the variables associated with this composition in order to find possible causes of deficiency, supporting strategies to prevent it in postpartum women and infants.

SOURCE

Studies published between 2004 and 2014 that assayed alpha-tocopherol in human milk of healthy women by high performance liquid chromatography were evaluated. The keywords used were "vitamin E", "alpha-tocopherol", "milk, human", "lactation", and equivalents in Portuguese, in the BIREME, CAPES, PubMed, SciELO, ISI Web of Knowledge, HighWire Press, Ingenta, and Brazilian Digital Library of Theses and Dissertations databases.

SUMMARY OF THE FINDINGS

Of the 41 publications found on the subject, 25 whose full text was available and met the inclusion criteria were selected. The alpha-tocopherol concentrations found in milk were similar in most populations studied. The variable phase of lactation was shown to influence vitamin E content in milk, which is reduced until the mature milk appears. Maternal variables parity, anthropometric nutritional status, socioeconomic status, and habitual dietary intake did not appear to affect the alpha-tocopherol levels in milk. However, the influence of the variables maternal age, gestational age, biochemical nutritional status in alpha-tocopherol, and maternal supplementation with vitamin E had conflicting results in the literature.

CONCLUSION

Alpha-tocopherol concentration in milk decreases during lactation, until the mature milk appears. To confirm the influence of some maternal and child variables on milk vitamin E content, further studies with adequate design are needed.

Vitamins, fatty acids, and antioxidant capacity stability during storage of freeze-dried human milk

Although freezing is the most common method used to preserve human milk, nutritional and immunological components may be lost during storage. Freeze-drying could increase the shelf life of human milk, while preserving its original characteristics. Seventy-two samples of freeze-dried human milk were stored for different periods of time, up to a maximum of 3 months, at 4 °C or 40 °C. Vitamin C, tocopherols, antioxidant capacity, and fatty acids composition were analyzed. A new HILIC-UHPLC method improving vitamin C determination was also validated. Ascorbic acid and total vitamin C concentrations significantly decreased at both temperatures, while antioxidant capacity only decreased at 40 °C. Fatty acids composition and both γ-tocopherol and δ-tocopherol contents remained unaltered. The stability after storage of freeze-dried milk was higher than that reported for frozen or fresh milk indicating that freeze-drying is a promising option to improve the preservation of human milk in banks.

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.