Variations in melatonin levels in preterm and term human breast milk during the first month after delivery

Teleological Considerations: Human Milk Collection for Research

We discuss the evolution and composition of breast milk and briefly describe how mammalian evolution resulted in lactation, which played a crucial role in infant growth and development. We focus on three teleological factors that significantly contribute to breast milk composition: (1) biological sex at birth, (2) gestational age, and (3) circadian rhythms. We also explain how these factors lead to variability in human milk composition. We emphasize the importance of standardizing the definitions of "preterm" and "term" to accurately study the effects of gestational age on milk composition. Finally, we discuss the role of the circadian clock in regulating lactation and the impact of breast milk on fetal and infant sleep. Investigators may integrate these critical factors when designing a research study that involves the collection of breast milk samples. Teleological factors greatly influence milk composition, and these factors may be considered when designing a study that requires breast milk. We provide both the rationale and application of solutions to address these factors.

Bioactive Components of Human Milk and Their Impact on Child's Health and Development, Literature Review

The composition of human breast milk is an ideal combination of substances necessary for the healthy development of an infant's body while protecting from pathogens and the balanced development of the microbiota. Its composition is dynamic and changes with the age of the child, meeting their current needs. The study provides a thorough overview of human milk components, such as immunological components, growth factors, hormones, carbohydrates, lipids, minerals, and vitamins. Authors focus on capturing the most important aspects of the effects of these substances on a newborn's body, while also looking for specific connections and describing the effects on given systems. Supplementation and the use of ingredients are also discussed. The purpose of this paper is to present the current state of knowledge about the bioactive components of human milk and their impact on the growth, development, and health of the young child.

Melatonin in Human Breast Milk and Its Potential Role in Circadian Entrainment: A Nod towards Chrononutrition?

Breastfeeding is the most appropriate source of a newborn's nutrition; among the plethora of its benefits, its modulation of circadian rhythmicity with melatonin as a potential neuroendocrine transducer has gained increasing interest. Transplacental transfer assures melatonin provision for the fetus, who is devoid of melatonin secretion. Even after birth, the neonatal pineal gland is not able to produce melatonin rhythmically for several months (with an even more prolonged deficiency following preterm birth). In this context, human breast milk constitutes the main natural source of melatonin: diurnal dynamic changes, an acrophase early after midnight, and changes in melatonin concentrations according to gestational age and during the different stages of lactation have been reported. Understudied thus far are the factors impacting on (changes in) melatonin content in human breast milk and their clinical significance in chronobiological adherence in the neonate: maternal as well as environmental aspects have to be investigated in more detail to guide nursing mothers in optimal feeding schedules which probably means a synchronized instead of mistimed feeding practice. This review aims to be thought-provoking regarding the critical role of melatonin in chrononutrition during breastfeeding, highlighting its potential in circadian entrainment and therefore optimizing (neuro)developmental outcomes in the neonatal setting.

Antiplatelet Effect of Melatonin through Breastfeeding: A Pediatric Case Report

We present a pediatric case of the antiplatelet effect of melatonin taken through breast milk in an 18-month-old child. The child was referred to our hematology outpatient clinic because of bleeding episodes that she presented since birth. Blood tests excluded the presence of blood coagulation diseases. The family history was negative for bleeding disorders. The child did not consume any drugs, food supplements, herbal teas or infusions. We performed an aggregation platelet test, which showed a reduced platelet aggregation. Shortly before, the baby had been breastfed. We speculated that breast milk could interfere with the result of the test; therefore, we decided to repeat the test in a fasting state. This time the test showed a normal platelet aggregation time. We learned that the child's mother was taking a mixture of valerian and melatonin. Thus, we decided to suspend maternal intake of melatonin and perform a new platelet aggregation test after three months. The test results were negative. After the suspension of melatonin, the patient did not present further bleeding events. In this case, melatonin, through the inhibition of platelet aggregation, had an important role on the hemostatic system of the child. Melatonin is considered as a dietary supplement and is mostly available as an alternative medicine without formal prescription and dosage regulation. It is important, especially during breastfeeding, to investigate personal and medication history, including also homeopathic remedies or dietary supplements.

Fetal SSRI antidepressant exposure and infant sleep: Findings from the MPEWS pregnancy cohort study

This longitudinal study examines the association between fetal Selective Serotonergic Reuptake Inhibitor antidepressant exposure and infant sleep behaviours at six and 12 months of age and focus on three of the most commonly prescribed antidepressants in pregnancy. This study utilises data on 698 women recruited at less than 20 weeks of pregnancy and are followed up at six and 12 months postpartum. Women were recruited into one of three groups: those taking either sertraline, citalopram or escitalopram antidepressants in pregnancy (n = 85); women with a depressive disorder who were not taking antidepressants (non-medicated depressed, NMD; n = 82); and, and a control group of women (n = 531). At six and 12 months, data were collected on breastfeeding and sleep location and infant sleep was measured using the Brief Infant Sleep Questionnaire. Antidepressants sertraline, escitalopram and citalopram were not associated with increased infant waking or time awake. However, sertraline was associated with longer time for an infant to go to sleep. This study provides reassurance that SSRI antidepressants and, in particular, sertraline, escitalopram and citalopram are not associated with infant sleep behaviours that are commonly regarded as problematic including night waking. Further replication of these findings, including with direct measures of infant sleep, are recommended.

Association of Breastfeeding Practices During the First 3 Months with Infant Sleep Trajectories: A Prospective Cohort Study

BACKGROUND

Breastfeeding has numerous effects on maternal and child health. The effect of breastfeeding on infant sleep remains inconclusive.

OBJECTIVES

We aimed to examine whether full breastfeeding (FBF) during the first 3 mo is associated with longitudinal infant sleep trajectories in their first 2 y of life.

METHODS

The study was embedded in the Tongji Maternal and Child Health Cohort study. Information on infant feeding practices was collected at 3 mo of age, and maternal/child pairs were assigned to the FBF or the non-FBF group (including partially breastfeeding and exclusive formula feeding) on the basis of feeding practices during the first 3 mo of life. Sleep data of infants were obtained at 3, 6, 12, and 24 mo. Total, night, and day sleep trajectories across 3 to 24 mo were estimated with group-based models. Each sleep trajectory was differentiated on the basis of sleep duration at 3 mo (long/moderate/short) and the interval from 6 to 24 mo (moderate/short). Multinomial logistic regression was used to investigate the association of breastfeeding practices with infant sleep trajectories.

RESULTS

Among the 4056 infants studied, 2558 (63.1%) received FBF for 3 mo. When compared with FBF infants, non-FBF infants had shorter sleep duration at 3, 6, and 12 mo (P < 0.01). Non-FBF infants were more likely to experience Moderate-Short (OR: 1.31; 95% CI: 1.06, 1.61) and Short-Short (OR: 1.56; 95% CI: 1.12, 2.16) total sleep trajectories and more likely to experience Moderate-Short (OR: 1.84; 95% CI: 1.22, 2.77), and Short-Moderate (OR: 1.40; 95% CI: 1.06, 1.85) night sleep trajectories than FBF infants.

CONCLUSIONS

Full breastfeeding for ≥3 mo were positively associated with longer infant sleep duration. Infants fully breastfed were more likely to experience better sleep trajectories characterized by longer duration in their first 2 y of life. Full breastfeeding may benefit infants through healthy sleep.

Integration of Time-Based Recommendations with Current Pediatric Health Behavior Guidelines: Implications for Obesity Prevention and Treatment in Youth

PURPOSE OF REVIEW

Youth-onset obesity is associated with negative health outcomes across the lifespan including cardiovascular diseases, type 2 diabetes, obstructive sleep apnea, dyslipidemias, asthma, and several cancers. Pediatric health guidelines have traditionally focused on the quality and quantity of dietary intake, physical activity, and sleep.

RECENT FINDINGS

Emerging evidence suggests that the timing (time of day when behavior occurs) and composition (proportion of time spent allocated to behavior) of food intake, movement (i.e., physical activity, sedentary time), and sleep may independently predict health trajectories and disease risks. Several theoretically driven interventions and conceptual frameworks feature behavior timing and composition (e.g., 24 h movement continuum, circadian science and chronobiology, intermittent fasting regimens, structured day hypothesis). These literatures are, however, disparate, with little crosstalk across disciplines. In this review, we examine dietary, sleep, and movement guidelines and recommendations for youths ages 0-18 in the context of theoretical models and empirical findings in support of time-based approaches. The review aims to inform a unifying framework of health behaviors and guide future research on the integration of time-based recommendations into current quantity and quality-based health guidelines for children and adolescents.

[Sleep patterns of infants and young children and their association with breastfeeding: a study based on K-means clustering]

OBJECTIVES

To investigate the sleep patterns and characteristics of infants and young children and the association between sleep patterns and breastfeeding.

METHODS

A general information questionnaire, Brief Infant Sleep Questionnaire (BISQ), and a questionnaire on feeding were used to investigate the sleep quality and feeding patterns of 1 148 infants and young children aged 7-35 months. The K-means clustering method was used to identify sleep patterns and characteristics. A multivariate logistic regression analysis was used to investigate the association between sleep patterns and breastfeeding.

RESULTS

Three typical sleep patterns were identified for the 1 148 infants and young children aged 7-35 months: early bedtime and long sleep time; short sleep latency and moderate sleep time; late bedtime, prolonged sleep latency, and insufficient sleep time. The third pattern showed sleep disorders. The multivariate logistic regression analysis showed that compared with formula feeding, exclusive breastfeeding within 6 months after birth reduced the risk of sleep disorder patterns by 69% (OR=0.31, 95%CI: 0.11-0.81). The risk of sleep disorder patterns was reduced by 40% (OR=0.60, 95%CI: 0.38-0.96) in the infants receiving breastfeeding for 4-6 months compared with those receiving breastfeeding for 1-3 months.

CONCLUSIONS

There are different sleep patterns in infants and young children, and breastfeeding can reduce the development of sleep disorder patterns.

Circadian Regulation of Hormonal Timing and the Pathophysiology of Circadian Dysregulation

Circadian rhythms are endogenously generated, daily patterns of behavior and physiology that are essential for optimal health and disease prevention. Disruptions to circadian timing are associated with a host of maladies, including metabolic disease and obesity, diabetes, heart disease, cancer, and mental health disturbances. The circadian timing system is hierarchically organized, with a master circadian clock located in the suprachiasmatic nucleus (SCN) of the anterior hypothalamus and subordinate clocks throughout the CNS and periphery. The SCN receives light information via a direct retinal pathway, synchronizing the master clock to environmental time. At the cellular level, circadian rhythms are ubiquitous, with rhythms generated by interlocking, autoregulatory transcription-translation feedback loops. At the level of the SCN, tight cellular coupling maintains rhythms even in the absence of environmental input. The SCN, in turn, communicates timing information via the autonomic nervous system and hormonal signaling. This signaling couples individual cellular oscillators at the tissue level in extra-SCN brain loci and the periphery and synchronizes subordinate clocks to external time. In the modern world, circadian disruption is widespread due to limited exposure to sunlight during the day, exposure to artificial light at night, and widespread use of light-emitting electronic devices, likely contributing to an increase in the prevalence, and the progression, of a host of disease states. The present overview focuses on the circadian control of endocrine secretions, the significance of rhythms within key endocrine axes for typical, homeostatic functioning, and implications for health and disease when dysregulated. © 2022 American Physiological Society. Compr Physiol 12: 1-30, 2022.

Effects of Antioxidants in Human Milk on Bronchopulmonary Dysplasia Prevention and Treatment: A Review

Bronchopulmonary dysplasia (BPD) is a severe chronic lung illness that affects neonates, particularly premature infants. It has far-reaching consequences for infant health and their families due to intractable short- and long-term repercussions. Premature infant survival and long-term quality of life are severely harmed by BPD, which is characterized by alveolarization arrest and hypoplasia of pulmonary microvascular cells. BPD can be caused by various factors, with oxidative stress (OS) being the most common. Premature infants frequently require breathing support, which results in a hyperoxic environment in the developing lung and obstructs lung growth. OS can damage the lungs of infants by inducing cell death, inhibiting alveolarization, inducing inflammation, and impairing pulmonary angiogenesis. Therefore, antioxidant therapy for BPD relieves OS and lung injury in preterm newborns. Many antioxidants have been found in human milk, including superoxide dismutase, glutathione peroxidase, glutathione, vitamins, melatonin, short-chain fatty acids, and phytochemicals. Human milk oligosaccharides, milk fat globule membrane, and lactoferrin, all unique to human milk, also have antioxidant properties. Hence, human milk may help prevent OS injury and improve BPD prognosis in premature infants. In this review, we explored the role of OS in the pathophysiology of BPD and related signaling pathways. Furthermore, we examined antioxidants in human milk and how they could play a role in BPD to understand whether human milk could prevent and treat BPD.

Birth, love, and fear: Physiological networks from pregnancy to parenthood

Pregnancy and childbirth are among the most dramatic physiological and emotional transformations of a lifetime. Despite their central importance to human survival, many gaps remain in our understanding of the temporal progression of and mechanisms underlying the transition to new parenthood. The goal of this paper is to outline the physiological and emotional development of the maternal-infant dyad from late pregnancy to the postpartum period, and to provide a framework to investigate this development using non-invasive timeseries. We focus on the interaction among neuroendocrine, emotional, and autonomic outputs in the context of late pregnancy, parturition, and post-partum. We then propose that coupled dynamics in these outputs can be leveraged to map both physiologic and pathologic pregnancy, parturition, and parenthood. This approach could address gaps in our knowledge and enable early detection or prediction of problems, with both personalized depth and broad population scale.

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Giving birth and caring for offspring are dynamic processes that can instill both love and fear.

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Maternal physiology continuously integrates fetal, social, and environmental cues.

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The result is coupled change in hormonal, autonomic nervous, and emotional output.

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Coupling may allow internal state to be assessed from peripheral autonomic markers.

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Such markers may identify healthy or pathologic pregnancy, parturition, and parenting, and enable creation of real-world tools.

Effects of Antioxidant Intake on Fetal Development and Maternal/Neonatal Health during Pregnancy

During pregnancy, cycles of hypoxia and oxidative stress play a key role in the proper development of the fetus. Hypoxia during the first weeks is crucial for placental development, while the increase in oxygen due to the influx of maternal blood stimulates endothelial growth and angiogenesis. However, an imbalance in the number of oxidative molecules due to endogenous or exogenous factors can overwhelm defense systems and lead to excessive production of reactive oxygen species (ROS). Many pregnancy complications, generated by systemic inflammation and placental vasoconstriction, such as preeclampsia (PE), fetal growth restriction (FGR) and preterm birth (PTB), are related to this increase of ROS. Antioxidants may be a promising tool in this population. However, clinical evidence on their use, especially those of natural origin, is scarce and controversial. Following PRISMA methodology, the current review addresses the use of natural antioxidants, such as epigallocatechin gallate (EGCG), melatonin and resveratrol (RESV), as well as other classical antioxidants (vitamin C and E) during the prenatal period as treatment of the above-mentioned complications. We review the effect of antioxidant supplementation on breast milk in lactating mothers.

Effect of pasteurization on melatonin concentration in human breast milk

Introduction

Women who have problems with lactation can use human milk banks. Mainly this human milk is provided to premature babies and sick newborns. Human milk is the most suitable food for newborns and infants, recommended by WHO (World Health Organization). Human milk has anti-inflammatory, anti-infective, and anti-allergic properties, and also works for immunomodulation. Melatonin has a special, underestimated importance in the composition of breast milk. It is a hormone that has many body functions and, for several decades, its antioxidant potential has been increasingly talked about.

The aim of the study was to examine the effect of Holder pasteurization on melatonin concentration in human milk.

Materials and Methods

18 samples of human milk from donors from the human milk bank were used for the analysis. Melatonin concentration before and after pasteurization was determined by ELISA. In addition, the nutritional content composition of milk was analyzed using MIRIS Human Milk Analyzer and correlations examined.

Results

Melatonin concentration in human milk before pasteurization was 0.65–26.24 pg/mL (Me=9.58, IQR=12.72), while after pasteurization 0.80–29.58 pg/mL (Me=9.98, IQR=11.26). There was a positive correlation between melatonin concentration before and after pasteurization (r=0.797, p<0.001).

Conclusions

The Holder pasteurization process does not affect the concentration of melatonin in milk samples, which may be a recommendation for human milk banks.

Influence of mothers' nighttime responses on the sleep-wake rhythm of 1-month-old infants

The purpose of this study was to analyze the influence of the mothers' nighttime responses on the sleep-wake rhythm of their 1-month-old infants. This study used an anonymous self-administered survey questionnaire with 1133 mothers of 1-month-old infants. The questionnaire investigated basic information about the parents, growth environment of infants, mothers' sleep patterns during pregnancy, and infants' sleep patterns at the age of one month. Logistic regression analysis was used to analyze the influence of nighttime responses on the risk of infants sleeping longer during the day than at night. Regarding nighttime response behavior, it was found that immediately picking up 1-month-old infants results in longer sleep during the day than at night (OR 1.616 [1.017 - 2.566], p = 0.042), compared to delaying picking up the infant. It was suggested that the stimulation due to picking up an infant may affect sleep-wake rhythm formation.

Sleep and Diet: Mounting Evidence of a Cyclical Relationship

Two factors intrinsic to health are diet and sleep. These two behaviors may well influence one another. Indeed, that insufficient sleep adversely impacts dietary intakes is well documented. On the other hand, diet may influence sleep via melatonin and its biosynthesis from tryptophan. Experimental data exist indicating that provision of specific foods rich in tryptophan or melatonin can improve sleep quality. Whole diets rich in fruits, vegetables, legumes, and other sources of dietary tryptophan and melatonin have been shown to predict favorable sleep outcomes. Although clinical trials are needed to confirm a causal impact of dietary patterns on sleep and elucidate underlying mechanisms, available data illustrate a cyclical relation between these lifestyle factors. We recommend adopting a healthful diet to improve sleep, which may further promote sustained favorable dietary practices.

Sudden infant death syndrome: Melatonin, serotonin, and CD34 factor as possible diagnostic markers and prophylactic targets

Sudden infant death syndrome (SIDS) is one of the primary causes of death of infants in the first year of life. According to the WHO's data, the global infant mortality rate is 0.64-2 per 1,000 live-born children. Molecular and cellular aspects of SIDS development have not been identified so far. The purpose of this paper is to verify and analyze the expression of melatonin 1 and 2 receptors, serotonin (as a melatonin precursor), and CD34 molecules (as hematopoietic and endothelial markers of cardiovascular damage) in the medulla, heart, and aorta in infants who died from SIDS. An immunohistochemical method was used to investigate samples of medulla, heart, and aorta tissues of infants 3 to 9 months of age who died from SIDS. The control group included children who died from accidents. It has been shown that the expression of melatonin receptors as well as serotonin and CD34 angiogenesis markers in tissues of the medulla, heart, and aorta of infants who died from SIDS is statistically lower as compared with their expression in the same tissues in children who died from accidents. The obtained data help to clarify in detail the role of melatonin and such signaling molecules as serotonin and CD34 in SIDS pathogenesis, which can open new prospects for devising novel methods for predictive diagnosis of development and targeted prophylaxis of SIDS.

High-throughput quantitation of trace level melatonin in human milk by on-line enrichment liquid chromatography-tandem mass spectrometry

The level of melatonin in human milk might be closely related to infant development and the building up of their circadian rhythms. The large population investigation on this topic would provide insights for the prevention and treatment of diseases related to early development and circadian rhythms. However, it has not been well studied. Trace level endogenous melatonin and difficulties in sample collection are among the challenges limiting the progress. High throughput analytical method with high specificity and sensitivity to determine the endogenous melatonin concentration is highly desired. A newly developed easily operated and high-throughput sensitive on-line enrichment liquid chromatography-tandem mass spectrometry (LC-MS/MS) method would be reported in this paper. Melatonin-d₃ (MEL-d₃) was used as a surrogate standard for the calibration curve and melatonin-d₄ (MEL-d₄) was used as an internal standard. Sample preparation was simply performed in 96-well plate by protein precipitation using acetonitrile (ACN). The supernatant was injected directly into the easily configured LC-MS/MS system with an enlarged sample loop and a mixer. Positive mode multiple reaction monitoring (MRM) was adopted for the measurement of melatonin in milk. 100 μL sample was used for analysis and the calibration curve linear range was 1-1000 pg mL^-1. In three validation batches, the accuracy was within 11.0% deviation from the relative nominal concentration, whereas the intra- and inter-assay precision was ≤4.1% and ≤6.8% relative standard deviation (RSD), respectively. Although matrix effect was observed in the validation experiments, the stable isotope labeled internal standard (MEL-d₄) could correct it and the overall relative matrix effect of MEL-d₃/MEL-d₄ was close to 100%. The overall spike recovery of the method was 101.7% with 5.1% RSD. Compared to currently reported methods, it could reach 1 pg mL^-1 lower limit of quantification (LLOQ) with a smaller sample volume, sample preparation could be easily performed by automated liquid handling system and was more suitable for large population cohort studies on trace level endogenous melatonin determination.

Melatonin in Early Nutrition: Long-Term Effects on Cardiovascular System

Breastfeeding protects against adverse cardiovascular outcomes in the long term. Melatonin is an active molecule that is present in the breast milk produced at night beginning in the first stages of lactation. This indoleamine appears to be a relevant contributor to the benefits of breast milk because it can affect infant health in several ways. The melatonin concentration in breast milk varies in a circadian pattern, making breast milk a chrononutrient. The consumption of melatonin can induce the first circadian stimulation in the infant's body at an age when his/her own circadian machinery is not functioning yet. This molecule is also a powerful antioxidant with the ability to act on infant cells directly as a scavenger and indirectly by lowering oxidant molecule production and enhancing the antioxidant capacity of the body. Melatonin also participates in regulating inflammation. Furthermore, melatonin can participate in shaping the gut microbiota composition, richness, and variation over time, also modulating which molecules are absorbed by the host. In all these ways, melatonin from breast milk influences weight gain in infants, limiting the development of obesity and comorbidities in the long term, and it can help shape the ideal cellular environment for the development of the infant's cardiovascular system.

Exosome-Derived MicroRNAs of Human Milk and Their Effects on Infant Health and Development

Multiple biologically active components of human milk support infant growth, health and development. Milk provides a wide spectrum of mammary epithelial cell-derived extracellular vesicles (MEVs) for the infant. Although the whole spectrum of MEVs appears to be of functional importance for the growing infant, the majority of recent studies report on the MEV subfraction of milk exosomes (MEX) and their miRNA cargo, which are in the focus of this review. MEX and the dominant miRNA-148a play a key role in intestinal maturation, barrier function and suppression of nuclear factor-κB (NF-κB) signaling and may thus be helpful for the prevention and treatment of necrotizing enterocolitis. MEX and their miRNAs reach the systemic circulation and may impact epigenetic programming of various organs including the liver, thymus, brain, pancreatic islets, beige, brown and white adipose tissue as well as bones. Translational evidence indicates that MEX and their miRNAs control the expression of global cellular regulators such as DNA methyltransferase 1-which is important for the up-regulation of developmental genes including insulin, insulin-like growth factor-1, α-synuclein and forkhead box P3-and receptor-interacting protein 140, which is important for the regulation of multiple nuclear receptors. MEX-derived miRNA-148a and miRNA-30b may stimulate the expression of uncoupling protein 1, the key inducer of thermogenesis converting white into beige/brown adipose tissue. MEX have to be considered as signalosomes derived from the maternal lactation genome emitted to promote growth, maturation, immunological and metabolic programming of the offspring. Deeper insights into milk's molecular biology allow the conclusion that infants are both "breast-fed" and "breast-programmed". In this regard, MEX miRNA-deficient artificial formula is not an adequate substitute for breastfeeding, the birthright of all mammals.

Antioxidative Molecules in Human Milk and Environmental Contaminants

Breastfeeding provides overall beneficial health to the mother-child dyad and is universally recognized as the preferred feeding mode for infants up to 6-months and beyond. Human milk provides immuno-protection and supplies nutrients and bioactive compounds whose concentrations vary with lactation stage. Environmental and dietary factors potentially lead to excessive chemical exposure in critical windows of development such as neonatal life, including lactation. This review discusses current knowledge on these environmental and dietary contaminants and summarizes the known effects of these chemicals in human milk, taking into account the protective presence of antioxidative molecules. Particular attention is given to short- and long-term effects of these contaminants, considering their role as endocrine disruptors and potential epigenetic modulators. Finally, we identify knowledge gaps and indicate potential future research directions.

Human milk composition promotes optimal infant growth, development and health

Human milk is a living dynamic fluid that promotes optimal nutrition and development of the infant and impacts health across the lifespan. This review reports on the diverse range of nutrients, immune protection factors, hormones, microbes and metabolites in human milk and their impacts on infant nutrition and health. While many of these components are stable across lactation and similar between women, some vary over time, and in response to maternal and infant health status, maternal diet and geographic location. Human milk may be considered as personalized nutrition, with many components working synergistically to stimulate and support the infant's immature immune system, while enhancing appropriate development, growth and body composition.

Melatonin rich foods in our diet: food for thought or wishful thinking?

Melatonin continues to generate interest in the scientific community and the general public. In recent years, there has been growing interest in the possibility that melatonin present in human foods may have physiological effects. This has led to the promotion of "melatonin-rich" foods and "phyto-melatonin". The night time secretion of endogenous melatonin from the pineal gland provides a daily circadian signal which is detected by receptors in various tissues. In animals the changing circadian pattern of melatonin secretion across seasons is important to them to program their reproductive behaviours to ensure optimal reproductive success, while in humans it probably plays a prominent role in anchoring sleep to the night period. When melatonin is administered in non-physiological, milligram amounts to humans, the onset of sleep can be manipulated and in larger doses anti-oxidant properties may emerge. Melatonin-rich foods are considered in this context too, but the question remains whether the amounts of melatonin in the food can be expected to be high enough to realistically change sleep or have antioxidant properties. In this review, papers reporting the effects of ingestion of melatonin-rich food on plasma or saliva melatonin or its urinary metabolite are critically evaluated. Unfortunately many of the papers are compromised by poor experimental design and assay methodologies and uncritical evaluation of results. The conclusion drawn from this review is that it is wishful thinking to expect that the amount of melatonin in "melatonin-rich" foods will impact on sleep or have any other physiological impact.

Melatonin Content of Human Milk: The Effect of Mode of Delivery

Objective: Cesarean section rates are increasing in developed countries and could be performed as an emergency or elective procedure. Our research aim was to determine whether elective cesarean section influences the melatonin content, the main circadian hormone, in human milk. Methods: Twenty-one women after vaginal delivery and 18 women after elective cesarean section were included. Only healthy mothers with normal newborns exclusively breastfed were recruited. Two samples of human milk were collected for each woman at three stages of lactation: colostrum, transitional milk, and mature milk; at each stage, one daytime sample and another nighttime sample were obtained. In total, 228 milk samples were studied. The melatonin content was analyzed by enzyme-linked immunosorbent assay. Results: Melatonin rhythmicity with higher melatonin content at night was maintained at each of the three stages of lactation, regardless of the type of delivery. A higher melatonin content was found in daytime colostrum after cesarean section with respect to colostrum obtained from mothers after vaginal delivery (30.3 pg/mL versus 14.7 pg/mL, p = 0.020). Melatonin content decreased progressively throughout the course of lactation in both groups. This decrease was significant when comparing transitional milk to colostrum in the cesarean group, both in the daytime (p = 0.016) and nighttime samples (p = 0.048). Conclusions: Cesarean section is associated with an increase in daytime colostrum melatonin. No difference was observed in mature milk with respect to vaginal delivery. Melatonin values in human milk decrease during the first month of lactation and circadian rhythmicity was observed irrespective of the mode of delivery.

Influence of Maternal Age and Gestational Age on Breast Milk Antioxidants During the First Month of Lactation

Breast milk (BM) is beneficial due to its content in a wide range of different antioxidants, particularly relevant for preterm infants, who are at higher risk of oxidative stress. We hypothesize that BM antioxidants are adapted to gestational age and are negatively influenced by maternal age. Fifty breastfeeding women from two hospitals (Madrid, Spain) provided BM samples at days 7, 14 and 28 of lactation to assess total antioxidant capacity (ABTS), thiol groups, reduced glutathione (GSH), superoxide dismutase (SOD) and catalase activities, lipid peroxidation (malondialdehyde, MDA + 4-Hydroxy-Trans-2-Nonenal, HNE), protein oxidation (carbonyl groups) (spectrophotometry) and melatonin (ELISA). Mixed random-effects linear regression models were used to study the influence of maternal and gestational ages on BM antioxidants, adjusted by days of lactation. Regression models evidenced a negative association between maternal age and BM melatonin levels (β = -7.4 ± 2.5; p-value = 0.005); and a negative association between gestational age and BM total antioxidant capacity (β = -0.008 ± 0.003; p-value = 0.006), SOD activity (β = -0.002 ± 0.001; p-value = 0.043) and protein oxidation (β = -0.22 ± 0.07; p-value = 0.001). In conclusion, BM antioxidants are adapted to gestational age providing higher levels to infants with lower degree of maturation; maternal ageing has a negative influence on melatonin, a key antioxidant hormone.

Melatonin's Impact on Antioxidative and Anti-Inflammatory Reprogramming in Homeostasis and Disease

There is a growing consensus that the antioxidant and anti-inflammatory properties of melatonin are of great importance in preserving the body functions and homeostasis, with great impact in the peripartum period and adult life. Melatonin promotes adaptation through allostasis and stands out as an endogenous, dietary, and therapeutic molecule with important health benefits. The anti-inflammatory and antioxidant effects of melatonin are intertwined and are exerted throughout pregnancy and later during development and aging. Melatonin supplementation during pregnancy can reduce ischemia-induced oxidative damage in the fetal brain, increase offspring survival in inflammatory states, and reduce blood pressure in the adult offspring. In adulthood, disturbances in melatonin production negatively impact the progression of cardiovascular risk factors and promote cardiovascular and neurodegenerative diseases. The most studied cardiovascular effects of melatonin are linked to hypertension and myocardial ischemia/reperfusion injury, while the most promising ones are linked to regaining control of metabolic syndrome components. In addition, there might be an emerging role for melatonin as an adjuvant in treating coronavirus disease 2019 (COVID 19). The present review summarizes and comments on important data regarding the roles exerted by melatonin in homeostasis and oxidative stress and inflammation related pathologies.

Circadian Variation in Human Milk Composition, a Systematic Review

Background: Breastfeeding is considered the most optimal mode of feeding for neonates and mothers. Human milk changes over the course of lactation in order to perfectly suit the infant’s nutritional and immunological needs. Its composition also varies throughout the day. Circadian fluctuations in some bioactive components are suggested to transfer chronobiological information from mother to child to assist the development of the biological clock. This review aims to give a complete overview of studies examining human milk components found to exhibit circadian variation in their concentration. Methods: We included studies assessing the concentration of a specific human milk component more than once in 24 h. Study characteristics, including gestational age, lactational stage, sampling strategy, analytical method, and outcome were extracted. Methodological quality was graded using a modified Newcastle-Ottawa Scale (NOS). Results: A total of 83 reports assessing the circadian variation in the concentration of 71 human milk components were included. Heterogeneity among studies was high. The methodological quality varied widely. Significant circadian variation is found in tryptophan, fats, triacylglycerol, cholesterol, iron, melatonin, cortisol, and cortisone. This may play a role in the child’s growth and development in terms of the biological clock.