Longitudinal investigation of the relationship between breast milk leptin levels and growth in breast-fed infants

Human Milk Bioactive Components and Child Growth and Body Composition in the First 2 Years: A Systematic Review

Human milk (HM) contains macronutrients, micronutrients, and a multitude of other bioactive factors, which can have a long-term impact on infant growth and development. We systematically searched MEDLINE, EMBASE, Cochrane Library, Scopus, and Web of Science to synthesize evidence published between 1980 and 2022 on HM components and anthropometry through 2 y of age among term-born infants. From 9992 abstracts screened, 141 articles were included and categorized based on their reporting of HM micronutrients, macronutrients, or bioactive components. Bioactives including hormones, HM oligosaccharides (HMOs), and immunomodulatory components are reported here, based on 75 articles from 69 unique studies reporting observations from 9980 dyads. Research designs, milk collection strategies, sampling times, geographic and socioeconomic settings, reporting practices, and outcomes varied considerably. Meta-analyses were not possible because data collection times and reporting were inconsistent among the studies included. Few measured infant HM intake, adjusted for confounders, precisely captured breastfeeding exclusivity, or adequately described HM collection protocols. Only 5 studies (6%) had high overall quality scores. Hormones were the most extensively examined bioactive with 46 articles (n = 6773 dyads), compared with 13 (n = 2640 dyads) for HMOs and 12 (n = 1422 dyads) for immunomodulatory components. Two studies conducted untargeted metabolomics. Leptin and adiponectin demonstrated inverse associations with infant growth, although several studies found no associations. No consistent associations were found between individual HMOs and infant growth outcomes. Among immunomodulatory components in HM, IL-6 demonstrated inverse relationships with infant growth. Current research on HM bioactives is largely inconclusive and is insufficient to address the complex composition of HM. Future research should ideally capture HM intake, use biologically relevant anthropometrics, and integrate components across categories, embracing a systems biology approach to better understand how HM components work independently and synergistically to influence infant growth.

Bioactive peptides in preterm human milk: Impact of maternal characteristics and their association to neonatal outcomes

Human milk adipokines in term babies seem partially determined by maternal factors and affect infant's development. We aimed to describe bioactive peptide concentration in very preterm human milk and associations to maternal characteristics and postnatal growth. Mothers delivering ≤32 weeks of gestation and their infant/s were recruited. At 4 weeks of lactation, an aliquot of 24-h-pooled milk was collected for exclusively breastfeeding dyads. Insulin, leptin, adiponectin, and milk fat globule epidermal growth factor-8 (MFG-E8) were measured by enzyme-linked immunoabsorbent assay in skimmed milk. One hundred mothers (28.8 ± 2.3 weeks at delivery) provided a milk sample. Milk insulin was related to gestational age, pre-pregnancy body mass index (BMI), and galactagogue treatment (final model: adjusted R2 : 0.330, p < 0.0001; adjusted β coefficients: galactagogue treatment: 0.348, p 0.001; pre-pregnancy BMI: 0.274, p 0.009; gestational age: -0.290, p 0.007). Adiponectin was higher in mothers with gestational diabetes (30.7 ± 6.5 vs. 24.8 ± 8 ng/mL, p 0.044). Leptin was associated with pre-pregnancy BMI (Spearman's ρ: 0.648, p < 0.0001) and MFG-E8 to presence of labor and multiple pregnancy (final linear regression model, R2 : 0.073, p 0.028, adjusted β coefficients: presence of labor -0.229, p 0.050; twins: -0.192, p 0.099). Milk adiponectin was associated with a greater decrease in length z-scores from birth to 28 days (Pearson's r: -0.225, p 0.032) and to discharge (Pearson's r: -0.290, p 0.003). Milk MFG-E8 was lower in milk of mothers whose babies experienced late-onset sepsis (13.3 ± 5.8 vs. 16.8 ± 6.3 μg/mL, p 0.023). Adipokines levels in preterm human milk are partially related to maternal metabolic status. Milk peptide concentration associates with early neonatal growth trajectories.

Specific Milk Composition of miR-30b Transgenic Mice Associated with Early Duodenum Maturation in Offspring with Lasting Consequences for Growth

BACKGROUND

Milk composition is complex and includes numerous components essential for offspring growth and development. In addition to the high abundance of miR-30b microRNA, milk produced by the transgenic mouse model of miR-30b-mammary deregulation displays a significantly altered fatty acid profile. Moreover, wild-type adopted pups fed miR-30b milk present an early growth defect.

OBJECTIVE

This study aimed to investigate the consequences of miR-30b milk feeding on the duodenal development of wild-type neonates, a prime target of suckled milk, along with comprehensive milk phenotyping.

METHODS

The duodenums of wild-type pups fed miR-30b milk were extensively characterized at postnatal day (PND)-5, PND-6, and PND-15 using histological, transcriptomic, proteomic, and duodenal permeability analyses and compared with those of pups fed wild-type milk. Milk of miR-30b foster dams collected at mid-lactation was extensively analyzed using proteomic, metabolomic, and lipidomic approaches and hormonal immunoassays.

RESULTS

At PND-5, wild-type pups fed miR-30b milk showed maturation of their duodenum with 1.5-fold (P < 0.05) and 1.3-fold (P < 0.10) increased expression of Claudin-3 and Claudin-4, respectively, and changes in 8 duodenal proteins (P < 0.10), with an earlier reduction in paracellular and transcellular permeability (183 ng/mL fluorescein sulfonic acid [FSA] and 12 ng/mL horseradish peroxidase [HRP], respectively, compared with 5700 ng/mL FSA and 90 ng/mL HRP in wild-type; P < 0.001). Compared with wild-type milk, miR-30b milk displayed an increase in total lipid (219 g/L compared with 151 g/L; P < 0.05), ceramide (17.6 μM compared with 6.9 μM; P < 0.05), and sphingomyelin concentrations (163.7 μM compared with 76.3 μM; P < 0.05); overexpression of 9 proteins involved in the gut barrier (P < 0.1); and higher insulin and leptin concentrations (1.88 ng/mL and 2.04 ng/mL, respectively, compared with 0.79 ng/mL and 1.06 ng/mL; P < 0.01).

CONCLUSIONS

miR-30b milk displays significant changes in bioactive components associated with neonatal duodenal integrity and maturation, which could be involved in the earlier intestinal closure phenotype of the wild-type pups associated with a lower growth rate.

Breast milk leptin concentrations and infant anthropometric indicators in SGA versus non-SGA breastfed infants born at term

Leptin concentrations in breast milk can influence metabolic programming during the first months of life. Small for gestational age (SGA) newborns show a peculiar growth pattern after birth, which can lead to adulthood diseases. This study aims to assess an association between leptin concentration in mature breast milk and the infant anthropometric indicators of the SGA and the non-SGA groups, in addition, to comparing the hormone level between these groups. A longitudinal study was performed with mother-infant pairs. The maternal sociodemographic information was collected in the first 48 h postpartum. Breast milk was collected at one month postpartum and leptin concentrations were obtained by immunoassays. The infant anthropometric measurements were collected at three and six months postpartum and included weight, height (to body mass index-BMI calculated), triceps skinfold (TSF), and subscapular skinfold (SSF). The BMI for age (BMI/A), TSF, and SSF were calculated by Z-score indicators. Data from 67 mother-infant pairs (n = 16 SGA and n = 51 non-SGA) were analyzed. In univariate analyses, the breast milk of the SGA group had lower leptin concentrations than the non-SGA group (p = 0.006), however, after adjustment, there was no difference between groups (p = 0.181). In the SGA group, there was a significant association between leptin concentrations and lower SSF at six months in infants, after adjustment (p = 0.003). In the non-SGA group, the breast milk leptin was associated with lower BMI/A at three and six months in infants, after adjustment (p = 0.002 and p = 0.010, respectively). The association between breast milk leptin concentrations with SSF in the SGA group and BMI/A in the non-SGA group suggests that leptin may be a modulating factor in infant growth in the first months of life.

Developmental Programming in Animal Models: Critical Evidence of Current Environmental Negative Changes

The Developmental Origins of Health and Disease (DOHaD) approach answers questions surrounding the early events suffered by the mother during reproductive stages that can either partially or permanently influence the developmental programming of children, predisposing them to be either healthy or exhibit negative health outcomes in adulthood. Globally, vulnerable populations tend to present high obesity rates, including among school-age children and women of reproductive age. In addition, adults suffer from high rates of diabetes, hypertension, cardiovascular, and other metabolic diseases. The increase in metabolic outcomes has been associated with the combination of maternal womb conditions and adult lifestyle-related factors such as malnutrition and obesity, smoking habits, and alcoholism. However, to date, "new environmental changes" have recently been considered negative factors of development, such as maternal sedentary lifestyle, lack of maternal attachment during lactation, overcrowding, smog, overurbanization, industrialization, noise pollution, and psychosocial stress experienced during the current SARS-CoV-2 pandemic. Therefore, it is important to recognize how all these factors impact offspring development during pregnancy and lactation, a period in which the subject cannot protect itself from these mechanisms. This review aims to introduce the importance of studying DOHaD, discuss classical programming studies, and address the importance of studying new emerging programming mechanisms, known as actual lifestyle factors, during pregnancy and lactation.

Enteral Nutrition: The Intricacies of Human Milk from the Immune System to the Microbiome

In 2012, the American Academy of Pediatrics stated that all preterm infant diets should consist of human milk (mother's own milk or pasteurized donor human milk). The clinical reasons supporting this policy are many, including reducing infections and retinopathy of prematurity, decreased neonatal intensive care unit length of stay, subsequent readmissions, a decrease in mortality, and improved neurodevelopmental outcomes. This article focuses on human milk, its composition and bioactive factors, and how it affects the gut-brain axis through the microbiome. We examine how differences between mother's own milk and pasteurized donor human milk affect the premature infant.

Leptin Levels of the Perinatal Period Shape Offspring's Weight Trajectories through the First Year of Age

Background: Leptin is a hormone regulating lifetime energy homeostasis and metabolism and its concentration is important starting from prenatal life. We aimed to investigate the association of perinatal leptin concentrations with growth trajectories during the first year of life. Methods: Prospective, longitudinal study, measuring leptin concentration in maternal plasma before delivery, cord blood (CB), and mature breast milk and correlating their impact on neonate’s bodyweight from birth to 1 year of age, in 16 full-term (FT), 16 preterm (PT), and 13 intrauterine growth-restricted (IUGR) neonates. Results: Maternal leptin concentrations were highest in the PT group, followed by IUGR and FT, with no statistical differences among groups (p = 0.213). CB leptin concentrations were significantly higher in FT compared with PT and IUGR neonates (PT vs. FT; IUGR vs. FT: p < 0.001). Maternal milk leptin concentrations were low, with no difference among groups. Maternal leptin and milk concentrations were negatively associated with all the neonates’ weight changes (p = 0.017 and p = 0.006), while the association with CB leptin was not significant (p = 0.051). Considering each subgroup individually, statistical analysis confirmed the previous results in PT and IUGR infants, with the highest value in the PT subgroup. In addition, this group’s results negatively correlated with CB leptin (p = 0.026) and showed the largest % weight increase. Conclusions: Leptin might play a role in neonatal growth trajectories, characterized by an inverse correlation with maternal plasma and milk. PT infants showed the highest correlation with hormone levels, regardless of source, seeming the most affected group by leptin guidance. Low leptin levels appeared to contribute to critical neonates’ ability to recover a correct body weight at 1 year. An eventual non-physiological “catch-up growth” should be monitored, and leptin perinatal levels may be an indicative tool. Further investigations are needed to strengthen the results.

Human Milk Metabolic Hormones: Analytical Methods and Current Understanding

Human milk (HM) contains a wide array of peptide hormones including leptin and adiponectin, which are involved in the regulation of infant growth and development. These essential hormones might play an important role in the regulation of metabolic reprogramming of the new-born infant. However, HM hormone studies are sparse and heterogeneous in regard to the study design, sample collection, preparation and analysis methods. This review discussed the limitations of HM hormone analysis highlighting the gaps in pre-analytical and analytical stages. The methods used to quantify HM metabolic hormones (leptin, adiponectin, ghrelin, insulin, obestatin, resistin and apelin) can be classified as immunoassay, immunosensor and chromatography. Immunoassay methods (ELISA and RIA) have been predominantly used in the measurement of these HM hormones. The relative validity parameters of HM hormones analysis are often overlooked in publications, despite the complexity and differences of HM matrix when compared to that of plasma and urine. Therefore, appropriate reports of validation parameters of methodology and instrumentation are crucial for accurate measurements and therefore better understanding of the HM metabolic hormones and their influences on infant outcomes.

The Relationship Between Breast Milk Components and the Infant Gut Microbiota

The assembly of the newborn's gut microbiota during the first months of life is an orchestrated process resulting in specialized microbial ecosystems in the different gut compartments. This process is highly dependent upon environmental factors, and many evidences suggest that early bacterial gut colonization has long-term consequences on host digestive and immune homeostasis but also metabolism and behavior. The early life period is therefore a "window of opportunity" to program health through microbiota modulation. However, the implementation of this promising strategy requires an in-depth understanding of the mechanisms governing gut microbiota assembly. Breastfeeding has been associated with a healthy microbiota in infants. Human milk is a complex food matrix, with numerous components that potentially influence the infant microbiota composition, either by enhancing specific bacteria growth or by limiting the growth of others. The objective of this review is to describe human milk composition and to discuss the established or purported roles of human milk components upon gut microbiota establishment. Finally, the impact of maternal diet on human milk composition is reviewed to assess how maternal diet could be a simple and efficient approach to shape the infant gut microbiota.

Association between breast milk adipokines with growth in breast feeding infants, a systematic review and meta-analysis

Objectives

Breast milk adipokines are associated with growth, body mass index (BMI) and weight gain in infants. In this study, the effect of breastmilk adipokines (leptin and adiponectin) on the BMI and weight gain of breast-fed infants was evaluated using systematic review and meta-analysis.

Materials and methods

We used PRISMA checklist for carrying out this study. 752 articles were collected from the database searching and other sources from 1994 to April 2019. According to the criteria in the study, 25 articles remained for evaluation. Eight papers were related to the effect of breast milk leptin on weight gain and BMI of infants that were evaluated by meta-analyzing. The adiponectin articles were surveyed by systematic review.

Results

There was no significant publication bias in the meta-analysis study. The results of random-effect model indicated a reverse and significant correlation between breastmilk leptin with weight gain and BMI (r=−0.331). The adiponectin level in breast milk was associated with the BMI and weight gain of infants.

Conclusions

Meta-analysis indicated a significant inverse correlation between breastmilk leptin with weight gain and BMI in infants; furthermore, the systematic review study expressed significant correlation between breast milk adiponectin with growth (BMI and weight gain) in infants.

Leptin: Master Regulator of Biological Functions that Affects Breathing

Obesity is a global epidemic in developed countries accounting for many of the metabolic and cardiorespiratory morbidities that occur in adults. These morbidities include type 2 diabetes, sleep-disordered breathing (SDB), obstructive sleep apnea, chronic intermittent hypoxia, and hypertension. Leptin, produced by adipocytes, is a master regulator of metabolism and of many other biological functions including central and peripheral circuits that control breathing. By binding to receptors on cells and neurons in the brainstem, hypothalamus, and carotid body, leptin links energy and metabolism to breathing. In this comprehensive article, we review the central and peripheral locations of leptin's actions that affect cardiorespiratory responses during health and disease, with a particular focus on obesity, SDB, and its effects during early development. Obesity-induced hyperleptinemia is associated with centrally mediated hypoventilation with decrease CO₂ sensitivity. On the other hand, hyperleptinemia augments peripheral chemoreflexes to hypoxia and induces sympathoexcitation. Thus, "leptin resistance" in obesity is relative. We delineate the circuits responsible for these divergent effects, including signaling pathways. We review the unique effects of leptin during development on organogenesis, feeding behavior, and cardiorespiratory responses, and how undernutrition and overnutrition during critical periods of development can lead to cardiorespiratory comorbidities in adulthood. We conclude with suggestions for future directions to improve our understanding of leptin dysregulation and associated clinical diseases and possible therapeutic targets. Lastly, we briefly discuss the yin and the yang, specifically the contribution of relative adiponectin deficiency in adults with hyperleptinemia to the development of metabolic and cardiovascular disease. © 2020 American Physiological Society. Compr Physiol 10:1047-1083, 2020.

Leptin as a breast milk component for the prevention of obesity

Leptin ingested as a component of breast milk is increasingly recognized to play a role in the postnatal programming of a healthy phenotype in adulthood. Besides its primary function in controlling body weight, leptin may be an essential nutrient required during lactation to ensure that the system controlling fat accumulation and body composition is well organized from the early stages of development. This review delves into the following topics: (1) the imprinted protective function of adequate leptin intake during lactation in future metabolic health; (2) the consequences of a lack of leptin intake or of alterations in leptin levels; and (3) the mechanisms described for the effects of leptin on postnatal programming. Furthermore, it highlights the importance of breastfeeding and the need to establish optimal or reference intake values for leptin during lactation to design patterns of personalized nutrition from early childhood.

A Review of Bioactive Factors in Human Breastmilk: A Focus on Prematurity

Preterm birth is an increasing worldwide problem. Prematurity is the second most common cause of death in children under 5 years of age. It is associated with a higher risk of several pathologies in the perinatal period and adulthood. Maternal milk, a complex fluid with several bioactive factors, is the best option for the newborn. Its dynamic composition is influenced by diverse factors such as maternal age, lactation period, and health status. The aim of the present review is to summarize the current knowledge regarding some bioactive factors present in breastmilk, namely antioxidants, growth factors, adipokines, and cytokines, paying specific attention to prematurity. The revised literature reveals that the highest levels of these bioactive factors are found in the colostrum and they decrease along the lactation period; bioactive factors are found in higher levels in preterm as compared to full-term milk, they are lacking in formula milk, and decreased in donated milk. However, there are still some gaps and inconclusive data, and further research in this field is needed. Given the fact that many preterm mothers are unable to complete breastfeeding, new information could be important to develop infant supplements that best match preterm human milk.

Adipokines in human breast milk

The review describes the molecular characteristics of so far detected breast milk adipokines and ranks their breast milk level compared to the respective levels in maternal and infant blood. Moreover, analytical knowledge for measurements of breast milk adipokines will be delineated. Next, we summarized data about two main potential influencing factors on adipokine concentration in breast milk, maternal weight and pasteurization of milk. Finally, associations between adipokines in breast milk and weight gain in infants as well as the putative mechanisms for effects of breast milk adipokines on food intake and weight gain in later life will debated. Our findings suggest that a source of adipokines in human breast milk cannot be uniformly defined. In dependence on the ratio between serum and breast milk levels the major quantity of these proteins may be derived from peripheral tissues, from the breast tissue itself or from both. Thus, leptin and in part adiponectin levels in breast milk are dependent on a plenty of influencing factors with an important relevance of maternal anthropometric characteristics There is some evidence that leptin, adiponectin and ghrelin levels in breast milk may be associated with growth gain of infants and even with increased risk for being overweight during infancy or childhood. We hypothesize that a dysregulation in adipokine homeostasis in early life could promote obesity and metabolic disturbance in later life.

Contribution of relative leptin and adiponectin deficiencies in premature infants to chronic intermittent hypoxia: Exploring a new hypothesis

Chronic intermittent hypoxia (CIH) occurs frequently in premature infants who have apnea of prematurity. Immaturity of the respiratory network from low central respiratory drive and the greater contribution of the carotid body on baseline breathing leads to respiratory instability in premature infants presenting as apnea and periodic breathing. During the 2nd week after birth, the smallest and the youngest premature infants have increased frequency of apnea and periodic breathing and associated oxygen desaturations that can persist for weeks after birth. CIH increases the production of reactive oxygen species that causes tissue damage. Premature infants have decreased capacity to scavenge reactive oxygen species. Oxidative injury is the cause of many of the co-morbidities that are seen in premature infants. In this review we discuss who low fat mass and the resulting relative deficiencies in leptin and adiponectin could contribute to the increase frequency of oxygen desaturations that occurs days after birth in the smallest and youngest premature infants. Leptin is a central respiratory stimulant and adiponectin protects the lung from vascular leak, oxidative injury and vascular remodeling.

Uteroplacental insufficiency reduces rat plasma leptin concentrations and alters placental leptin transporters: ameliorated with enhanced milk intake and nutrition

KEY POINTS

Uteroplacental insufficiency compromises maternal mammary development, milk production and pup organ development; this is ameliorated by cross-fostering, which improves pup growth and organ development and prevents adult diseases in growth-restricted (Restricted) offspring by enhancing postnatal nutrition. Leptin is transported to the fetus from the mother by the placenta; we report reduced plasma leptin concentrations in Restricted fetuses associated with sex-specific alterations in placental leptin transporter expression. Pup plasma leptin concentrations were also reduced during suckling, which may suggest reduced milk leptin transport or leptin reabsorption. Mothers suckled by Restricted pups had impaired mammary development and changes in milk fatty acid composition with no alterations in milk leptin; cross-fostering restored pup plasma leptin concentrations, which may be correlated to improved milk composition and intake. Increased plasma leptin and altered milk fatty acid composition in Restricted pups suckling mothers with normal lactation may improve postnatal growth and prevent adult diseases.

ABSTRACT

Uteroplacental insufficiency reduces birth weight and adversely affects fetal organ development, increasing adult disease risk. Cross-fostering improves postnatal nutrition and restores these deficits. Mothers with growth-restricted pups have compromised milk production and composition; however, the impact cross-fostering has on milk production and composition is unknown. Plasma leptin concentrations peak during the completion of organogenesis, which occurs postnatally in rats. Leptin is transferred to the fetus via the placenta and to the pup via the lactating mammary gland. This study investigated the effect of uteroplacental insufficiency on pup plasma leptin concentrations and placental leptin transporters. We additionally examined whether cross-fostering improves mammary development, milk composition and pup plasma leptin concentrations. Fetal growth restriction was induced by bilateral uterine vessel ligation surgery on gestation day 18 in Wistar Kyoto rats (termed uteroplacental insufficiency surgery mothers). Growth-restricted (Restricted) fetuses had reduced plasma leptin concentrations, persisting throughout lactation, and sex-specific alterations in placental leptin transporters. Mothers suckled by Restricted pups had impaired mammary development, altered milk fatty acid composition and increased plasma leptin concentrations, despite no changes in milk leptin. Milk intake was reduced in Restricted pups suckling uteroplacental insufficiency surgery mothers compared to Restricted pups suckling sham-operated mothers. Cross-fostering Restricted pups onto a sham-operated mother improved postnatal growth and restored plasma leptin concentrations compared to Restricted pups suckling uteroplacental insufficiency surgery mothers. Uteroplacental insufficiency alters leptin homeostasis. This is ameliorated with cross-fostering and enhanced milk fatty acid composition and consumption, which may protect the pups from developing adverse health conditions in adulthood.

Variation of Metabolite and Hormone Contents in Human Milk

Animal studies show that the lactation period contributes to metabolic programming of the offspring and that oral leptin and insulin show bioactivity. Stage of lactation, duration of gestation, maternal body composition, and maternal diet seem to influence the concentrations of small molecules in human milk. Variability of small molecule concentrations seems higher in preterm milk than in term milk. Insulin in human milk shows concentrations similar to plasma. Leptin concentration is lower in milk than in plasma and reflects maternal body mass index. Early in lactation, leptin could contribute to mediating the association between maternal and infant body composition.

Modeling the impact of growth and leptin deficits on the neuronal regulation of blood pressure

The risk of hypertension is increased by intrauterine growth restriction (IUGR) and preterm birth. In the search for modifiable etiologies for this life-threatening cardiovascular morbidity, a number of pathways have been investigated, including excessive glucocorticoid exposure, nutritional deficiency and aberration in sex hormone levels. As a neurotrophic hormone that is intimately involved in the cardiovascular regulation and whose levels are influenced by glucocorticoids, nutritional status and sex hormones, leptin has emerged as a putative etiologic and thus a therapeutic agent. As a product of maternal and late fetal adipocytes and the placenta, circulating leptin typically surges late in gestation and declines after delivery until the infant consumes sufficient leptin-containing breast milk or accrues sufficient leptin-secreting adipose tissue to reestablish the circulating levels. The leptin deficiency seen in IUGR infants is a multifactorial manifestation of placental insufficiency, exaggerated glucocorticoid exposure and fetal adipose deficit. The preterm infant suffers from the same cascade of events, including separation from the placenta, antenatal steroid exposure and persistently underdeveloped adipose depots. Preterm infants remain leptin deficient beyond term gestation, rendering them susceptible to neurodevelopmental impairment and subsequent cardiovascular dysregulation. This pathologic pathway is efficiently modeled by placing neonatal mice into atypically large litters, thereby recapitulating the perinatal growth restriction-adult hypertension phenotype. In this model, neonatal leptin supplementation restores the physiologic leptin surge, attenuates the leptin-triggered sympathetic activation in adulthood and prevents leptin- or stress-evoked hypertension. Further pathway interrogation and clinical translation are needed to fully test the therapeutic potential of perinatal leptin supplementation.

Maternal characteristics associated with milk leptin content in a sample of Filipino women and associations with infant weight for age

BACKGROUND

Human milk contains many metabolic hormones that may influence infant growth. Milk leptin is positively associated with maternal adiposity and inversely associated with infant growth. Most research has been conducted in populations with higher leptin levels; it is not well understood how milk leptin may vary in lean populations or the associations that reduced leptin may have with infant size for age. It is also largely unknown if associations between maternal body composition and milk leptin persist past 1 year of age.

OBJECTIVES

We investigated the association between maternal body composition and milk leptin content in a sample of lean Filipino women and the association between milk leptin content and infant size for age.

METHODS

Milk samples were collected at in-home visits from 113 mothers from Cebu, Philippines. Milk leptin content was measured using EIA techniques; anthropometric data, dietary recalls, and household information were also collected.

RESULTS

Mean ± standard deviation (SD) milk leptin in this sample was 300.7 ± 293.6 pg/mL, among the lowest previously reported. Mean ± SD maternal percentage body fat was 24.8% ± 3.5%. Mean ± SD infant age was 9.9 ± 7.0 months, and mean ± SD weight for age z-score was -0.98 ± 1.06. Maternal percentage body fat was a significant, positive predictor of milk leptin content. Milk leptin was a significant, inverse predictor of infant weight and body mass index z-scores in infants 1 year old or younger.

CONCLUSION

The association between maternal body composition, milk leptin, and infant growth persists in mothers with lean body composition. Milk leptin is not associated with growth in older infants.

Leptin in pregnancy and development: a contributor to adulthood disease?

Emerging research has highlighted the importance of leptin in fetal growth and development independent of its essential role in the maintenance of hunger and satiety through the modulation of neuropeptide Y and proopiomelanocortin neurons. Alterations in maternal-placental-fetal leptin exchange may modify the development of the fetus and contribute to the increased risk of developing disease in adulthood. In addition, leptin also plays an important role in reproductive functions, with plasma leptin concentrations rising in pregnant women, peaking during the third trimester. Elevated plasma leptin concentrations occur at the completion of organogenesis, and research in animal models has demonstrated that leptin is involved in the development and maturation of a number of organs, including the heart, brain, kidneys, and pancreas. Elevated maternal plasma leptin is associated with maternal obesity, and reduced fetal plasma leptin is correlated with intrauterine growth restriction. Alterations in plasma leptin during development may be associated with an increased risk of developing a number of adulthood diseases, including cardiovascular, metabolic, and renal diseases via altered fetal development and organogenesis. Importantly, research has shown that leptin antagonism after birth significantly reduces maturation of numerous organs. Conversely, restoration of the leptin deficiency after birth in growth-restricted animals restores the offspring's body weight and improves organogenesis. Therefore, leptin appears to play a major role in organogenesis, which may adversely affect the risk of developing a number of diseases in adulthood. Therefore, greater understanding of the role of leptin during development may assist in the prevention and treatment of a number of disease states that occur in adulthood.

Effect of maternal body mass index on hormones in breast milk: a systematic review

Background

Maternal Body Mass Index (BMI) is positively associated with infant obesity risk. Breast milk contains a number of hormones that may influence infant metabolism during the neonatal period; these may have additional downstream effects on infant appetite regulatory pathways, thereby influencing propensity towards obesity in later life.

Objective

To conduct a systematic review of studies examining the association between maternal BMI and the concentration of appetite-regulating hormones in breast milk.

Method

Pubmed was searched for studies reporting the association between maternal BMI and leptin, adiponectin, insulin, ghrelin, resistin, obestatin, Peptide YY and Glucagon-Like Peptide 1 in breast milk.

Results

Twenty six studies were identified and included in the systematic review. There was a high degree of variability between studies with regard to collection, preparation and analysis of breast milk samples. Eleven of fifteen studies reporting breast milk leptin found a positive association between maternal BMI and milk leptin concentration. Two of nine studies investigating adiponectin found an association between maternal BMI and breast milk adiponectin concentration; however significance was lost in one study following adjustment for time post-partum. No association was seen between maternal BMI and milk adiponectin in the other seven studies identified. Evidence for an association between other appetite regulating hormones and maternal BMI was either inconclusive, or lacking.

Conclusions

A positive association between maternal BMI and breast milk leptin concentration is consistently found in most studies, despite variable methodology. Evidence for such an association with breast milk adiponectin concentration, however, is lacking with additional research needed for other hormones including insulin, ghrelin, resistin, obestatin, peptide YY and glucagon-like peptide-1. As most current studies have been conducted with small sample sizes, future studies should ensure adequate sample sizes and standardized methodology.

Adipokines in breast milk: an update

Epidemiological surveys indicate that nutrition in infancy is implicated in the long-term tendency to obesity and that a longer duration of breastfeeding is associated with a protective effect against metabolic disorders later in life. However, the precise cause of this association is not well understood. Recent studies on the compounds present in human breast milk have identified various adipokines, including leptin, adiponectin, resistin, obestatin, nesfatin, ghrelin and apelins. Some of these compounds are involved in the regulation of food intake and energy balance. The presence of these adipokines in breast milk suggests that they may be responsible for the regulation of growth in early infancy and that they could influence the energy balance and development of metabolic disorders in childhood and adulthood.

Serum reference values for leptin in healthy infants

Objective

Reports on leptin concentrations in pediatric populations lack reference values for infants in the first months of life. Our study was conducted on healthy full-term infants between 2002 and 2012 to determine serum leptin reference values in subjects less than 18 months old.

Methods

Routine outpatient blood tests for serum leptin were performed on 317 infants using a radioimmunoassay method. The median and 10^th–90^th percentiles were calculated to obtain reference values using quantile regression. Values established in this study were compared with another independent cohort of 110 infants.

Results

The median (IQR) serum leptin concentration in the infants was 2.37 (3.26) ng/ml (n = 317). The median leptin concentration was 2.81 (3.49) ng/ml (n = 202) in infants younger than 6 months of age, 1.44 (2.27) ng/ml (n = 59) in infants between 6–12 months of age and 1.77 (2.05) ng/ml (n = 56) in infants between 12–18 months of age. We obtained leptin reference values based on age by estimating the lower and upper percentiles. In the entire cohort, the median (IQR) leptin concentration was 2.22 (3.11) ng/ml in males (n = 168) and 2.60 (3.32) ng/ml in females (n = 149). According to the type of feeding median serum leptin concentration was higher in breast-fed infants (n = 188) than in formula-fed infants (n = 129) (2.63 (3.34) ng/ml vs. 2.12 (2.77) ng/ml; p<0.05).

Conclusions

Our data revealed no gender difference in leptin concentration in early infancy. After 6 months of life, leptin concentrations decreased slightly. We used a large cohort to confirm that breast-fed infants had significantly higher serum leptin levels than formula-fed infants during the first 6 months of life, although this difference disappeared later in life. In this study, we defined the leptin reference range in healthy infants in the first 18 months of life according to the Clinical and Laboratory Standards Institute (CLSI).

The relationship between ghrelin and adiponectin levels in breast milk and infant serum and growth of infants during early postnatal life

Ghrelin and adiponectin have been found in breast milk and are considered to take part in the regulation of growth and energy metabolism of infants. Our aims were to determine ghrelin and adiponectin levels in breast milk and serum samples of mothers and their infants, and to investigate the relationship between their levels and anthropometry of newborn infants during early postnatal life. Total and active ghrelin and adiponectin levels were studied in breast milk, and the serum samples of 25 healthy lactating women and their healthy fullterm infants were taken at the 1st and 4th months of life. Anthropometric measurements of infants were also performed during the study period. Breast milk and infant serum active ghrelin levels were found to be significantly increased at the 4th month of life compared with 1st month levels (p < 0.05). Maternal serum total ghrelin and infant serum adiponectin levels were found to be significantly reduced at the 4th month of life (p < 0.05). Breast milk active ghrelin levels were higher than the infant and maternal serum active ghrelin at the 1st and 4th months (p < 0.05). There was a negative significant correlation between the level of infant serum active ghrelin levels and BMI of infants at the 1st month. A positive significant correlation was found between the level of 1st month infant serum adiponectin levels and weight gain of infants during the study period. Fourth month infant serum adiponectin were also positively correlated with weight and BMI of infants at the 4th month and the weight gain during study period. There was a positive significant correlation between the level of 4th month breast milk active ghrelin and weight gain of infants during the study period. Ghrelin and adiponectin are involved in postnatal growth of infants. Ghrelin in breast milk also seems to be related to the growth of infants during early postnatal life. The sources of these peptides in breast milk are probably both maternal serum and breast tissue itself.

The human obesity epidemic, the mismatch paradigm, and our modern "captive" environment

In the distant past obesity in humans was rare and likely caused by metabolic dysregulation due to genetic or disease-related pathology. External factors precluded the ability of most people to overeat or under exert. Socio-cultural obesity came about due to the rareness of obesity and its difficulty to achieve. What is rare becomes valuable and what is difficult to achieve becomes a badge of prestige. The modern human obesity epidemic would appear to represent a third class of obesity: environmental obesity. Much like the captive environments which humans construct for the captive/companion animals in our care, the modern human environment has greatly decreased the challenges of life that would restrict food intake and enforce exertion. And like us, our captive/companion animal populations are also experiencing obesity epidemics. A further concern is that maternal obesity alters maternal signaling to offspring, in utero through the placenta and after birth through breast milk, in ways that perpetuate an enhanced vulnerability to obesity. Molecules such as leptin, produced by adipose tissue and placenta, have significant developmental effects on brain areas associated with feeding behavior. Leptin and other cytokines and growth factors are found in breast milk. These molecules have positive effects on gut maturation; their effects on metabolism and brain development are unclear. Placenta and brain also are hotspots for epigenetic regulation, and epigenetic changes may play significant roles in the later vulnerability to obesity and to the development of a diverse array of diseases, including heart disease, hypertension, and noninsulin-dependent diabetes.

Serum levels of leptin, adiponectin and resistin are interrelated and related to total antioxidant capacity, free fatty acids and phospholipids in early neonatal life

OBJECTIVES

The aims of this study were to determine interrelationships between serum leptin, adiponectin and resistin, insulin-like growth factor-1 (IGF-1), total antioxidant capacity (TAC), non-esterified fatty acids (NEFA) and phospholipids concentrations in infants.

DESIGN AND METHODS

A cross-sectional study was conducted to assess serum levels of leptin, adiponectin, resistin, IGF-1, TAC, NEFA and phospholipids in 45 breast-fed infants enrolled at 4-30 days after birth.

RESULTS

Serum leptin and adiponectin concentrations were positively correlated. Serum resistin concentrations were inversely correlated to serum leptin and adiponectin concentrations. Serum TAC was positively correlated to serum leptin and adiponectin, and inversely to serum resistin concentrations. Serum adiponectin concentrations were positively related to serum NEFA and phospholipid concentrations. Serum resistin concentrations were inversely related to serum NEFA, and phospholipid concentrations.

CONCLUSION

These data show that circulatory levels of leptin, adiponectin and resistin are interrelated and they apparently interact with the anti-oxidant system of infants.

Maternal obesity, metabolic disease, and allostatic load

Maternal obesity is a risk factor for many metabolic diseases for the mother, both during gestation and post partum, and for the child in later life. Obesity and pregnancy both result in altered physiological states, significantly different from the state of the non-obese, non-reproductive adult female. The concept of allostasis may be more appropriate for understanding the physiology of both pregnancy and obesity. In pregnancy these altered physiological states are adaptive, in both the evolutionary and physiological senses of the word. Obesity, however, represents a state outside of the adaptive evolutionary experience of our species. In both cases the altered physiological state derives at least in part from signals from an active endocrine organ. In obesity this is adipose tissue, and in pregnancy it is the placenta. The signaling molecules from adipose tissue and placenta all have multiple functions and can affect multiple organ systems. Placenta acts as a central regulator of metabolism for both the maternal and fetal compartments, in essence acting as a "third brain" during pregnancy. Both adipose tissue and placenta express many proinflammatory cytokines; obesity and pregnancy are states of low-grade inflammation. Both obesity and pregnancy are also states of insulin resistance, and maternal obesity is associated with fetal insulin resistance. We argue that obesity during pregnancy leads to sustained and inappropriate activation of normally adaptive regulatory circuits due in part to competing and conflicting signaling from adipose tissue and placenta. This results in allostatic load, leading to the eventual break down of regulatory mechanisms. The result is impaired metabolic function of the mother, and altered development of metabolic systems and potentially altered neural appetite circuits for the offspring.

Leptin determination in colostrum and early human milk from mothers of preterm and term infants

BACKGROUND

Leptin is involved in the regulation of food intake and energy expenditure and is therefore important for growth and brain development. Analytical methods used for leptin measurement in human milk differ widely in the literature and yield varying results.

AIMS

To compare different preparation methods for the analysis of leptin in human milk and to investigate the leptin levels in colostrum and mature human milk from mothers of preterm or term infants.

METHODS

Mothers delivering a preterm (n=37) or a term infant (n=40) were recruited for a prospective study and were ask to collect breast milk on the 3rd and 28th day of lactation. Leptin, protein and fat concentrations were analysed. Clinical data of mother and child were recorded prospectively.

RESULTS

Skim milk was most appropriate for leptin analysis. Human milk leptin concentrations did not differ between preterm and term human milk. In term milk, leptin concentration on day 28 was lower than on day 3 (p<0.05). Milk leptin levels on the 3rd and 28th day were positively correlated with mothers' body mass index, but not with fat content in milk.

CONCLUSION

Skim milk was the most stabile preparation for leptin analysis. Preterm and term human milk contain leptin in equal concentrations. Human milk leptin depends on mothers' body mass index.

Can hormones contained in mothers' milk account for the beneficial effect of breast-feeding on obesity in children?

Nutrition and growth during infancy are an emerging issue because of their potential link to metabolic health disorders in later life. Moreover, prolonged breast-feeding appears to be associated with a lower risk of obesity than formula feeding. Human milk is a source of various hormones and growth factors, namely adipokines (leptin and adiponectin), ghrelin, resistin and obestatin, which are involved in food intake regulation and energy balance. These compounds are either not found in commercial milk formulas or their presence is still controversial. Diet-related differences during infancy in serum levels of factors involved in energy metabolism might explain anthropometric differences and also differences in dietary habits between breast-fed (BF) and formula-fed (FF) infants later in life, and may thus have long-term health consequences. In this context, the recent finding of higher leptin levels and lower ghrelin levels in BF than in FF infants suggests that differences in hormonal values together with different protein intake could account for the differences in growth between BF and FF infants both during infancy and later in life. In this review, we examine the data related to hormones contained in mothers' milk and their potential protective effect on subsequent obesity and metabolic-related disorders.

Breastfeeding in infancy and adult cardiovascular disease risk factors

BACKGROUND

Public health recommendations advocate breastfeeding in infancy as a means to reduce obesity in later life. Several prior studies relating breastfeeding to cardiovascular risk factors have been limited by lack of adjustment for maternal and participant confounding factors.

METHODS

We ascertained breastfeeding history via questionnaire from mothers enrolled in the Framingham Offspring Study. In their young to middle-aged adult children enrolled in the Framingham Third Generation, we examined the relations between maternal breastfeeding history (yes, no) and cardiovascular risk factors, including body mass index (BMI), high-density lipoprotein (HDL) cholesterol, total cholesterol, triglycerides, fasting blood glucose, and systolic and diastolic blood pressure levels. We applied generalized estimating equations to account for sibling correlations and adjusted for maternal and participant lifestyle, education, and cardiovascular risk factors.

RESULTS

In Third Generation participants (n = 962, mean age = 41 years, 54% were women), 26% of their mothers reported breastfeeding. Compared with non-breastfed individuals, breastfed adult participants had lower multivariable-adjusted BMI (26.1 kg/m2 vs 26.9 kg/m2, P = .04) and higher HDL cholesterol levels (HDL 56.6 mg/dL vs 53.7 mg/dL, P = .01). On additional adjustment for BMI, the association between breastfeeding and HDL cholesterol was attenuated (P = .09). Breastfeeding was not associated with total cholesterol, triglycerides, fasting blood glucose, systolic blood pressure, or diastolic blood pressure.

CONCLUSION

Breastfeeding in infancy is inversely associated with adult BMI and positively associated with HDL cholesterol. Associations between breastfeeding and BMI may mediate the association between breastfeeding and HDL cholesterol.

The relationship between breast milk leptin and neonatal weight gain

AIM

To investigate whether change in leptin content of breast milk during lactation acts on neonatal body weight gain.

METHODS

In total 15 lactating women and their 15 term infants were involved in the study. Breast milk and neonatal serum samples were obtained from the same women and their neonates on the 1st day and any day between the 21st and 30th days after birth. Breast milk and serum leptin concentrations were determined by radioimmunoassay. Anthropometric indexes of the infants were recorded.

RESULTS

The study was completed with 15 multiparious mothers aged 19-37 years and their infants. The mean collection time of the first samples after birth was 6.07 +/- 1.94 h. The leptin level in the mature milk was significantly higher than in the colostrum (p < 0.001). Neonatal weight and height were significantly increased on 21-30 lactation days compared to 1st day of lactation (p < 0.05 and p < 0.001, respectively). The leptin concentration in the mature milk was negatively correlated with delta BMI (r =-0.53; p < 0.05). The delta breast milk leptin concentration was also found to be inversely correlated with delta BMI (r =-0.529; p < 0.05).

CONCLUSION

The results of this study have suggested that change in the leptin content of breast milk during lactation might play a role in the regulation of weight gain in healthy neonates.

Opportunities for the primary prevention of obesity during infancy

Many parents, grandparents, and clinicians have associated a baby’s ability to eat and gain weight as a sign of good health, and clinicians typically only call significant attention to infant growth if a baby is failing to thrive or showing severe excesses in growth. Recent evidence, however, has suggested that pediatric healthcare providers should pay closer attention to growth patterns during infancy. Both higher weight and upward crossing of major percentile lines on the weight-for-age growth chart during infancy have long term health consequences, and are associated with overweight and obesity later in life. Clinicians should utilize the numerous available opportunities to discuss healthy growth and growth charts during health maintenance visits in the first two years after birth. Further, providers should instruct parents on strategies to promote healthy behaviors that can have long lasting obesity preventive effects.

Effects of a maternal low protein isocaloric diet on milk leptin and progeny serum leptin concentration and appetitive behavior in the first 21 days of neonatal life in the rat

Suboptimal developmental environments program offspring to lifelong metabolic problems. We evaluated effects of maternal isocaloric low protein diet during pregnancy and/or lactation on milk quantity and leptin concentration at postnatal day 7, 14, and 21. Control mothers ate 20% casein (C) and restricted mothers (R) 10% casein to provide four groups: CC, RR, CR, and RC (first letter pregnancy and second lactation diet) to enable evaluation of effects influenced by maternal diet during pregnancy and lactation. Milk leptin was not a determinant of pup serum leptin. Pup serum leptin did not inhibit milk appetite at any postnatal age. Pup serum leptin did not correlate with pup adipose tissue. Finally, the normal postnatal leptin rise in pup serum was delayed by prenatal undernutrition. These data suggest that fetal nutrition modifies timing of neonatal leptin surge and may contribute to the development of altered appetite and metabolic disorders in later life.

Looking for a relation between serum leptin concentration and body composition parameters in healthy term infants in the first 6 months of life

We carried out a cross-sectional study of 115 healthy infants, younger than 6 months old, exclusively breast-fed or formula-fed, to investigate correlations between circulating leptin concentrations and body composition measurements. Serum leptin was evaluated with radioimmunoassay, and body composition with bioelectrical impedance analysis. Multiple regression analysis showed a relationship between serum leptin and body mass index in the entire study population (P = 0.042). There was a significant negative relationship between serum leptin and phase angle (P = 0.006) in formula-fed infants. Serum leptin was positively related to subscapular skinfold thickness (P = 0.055) and negatively to reactance (P = 0.057) only in formula-fed infants, although the differences were just below significance. Serum leptin concentration was higher in breast-fed infants (P = 0.002), and was not correlated with body composition parameters. This study indicates that there is a relation between leptin and infant body composition in the first months of life, although the link needs to be explored further.

Update on breast milk hormones: leptin, ghrelin and adiponectin

Recent evidences suggest that a number of chronic diseases seems to be associated with early prenatal and postnatal nutrition, even though the mechanisms underlying the link between early nutrition, health and well-being later in life have not been well understood. Considering that overweight and obesity derive from a condition of altered energy balance, one of the major interests of nutritional researchers is to provide breakthroughs in the understanding of hormonal patterns involved in energy balance regulation. Epidemiological surveys indicate that breastfeeding is protective against obesity in later life, even if the precise magnitude of this association remains not well defined. A lot of studies have shown the detection of hormones in breast milk, which have a role in energy balance regulation. In this review, we present a synopsis of previous and recent studies focusing on hormones in breast milk. It appears that promoting breastfeeding is an important factor in this process.

Determinants of early life leptin levels and later life degenerative outcomes

The early (intrauterine and neonatal) life environment plays an important role in programming the susceptibility in later life to chronic degenerative diseases, such as obesity, cardiovascular diseases, diabetes mellitus, cancer and osteoporosis. Among other hormones, leptin plays a major role in the regulation of the overall metabolism and has multiple neuroendocrine (adeno- and neuro-hypophysis axes and the hypothalamus-pituitary-adrenal axis) and immune functions. The hormone exerts its actions beginning in the early life time period, regulating the intrauterine and early extrauterine life growth and development, as well as the adaptation to extrauterine life, neonatal thermogenesis and response to stress. Recent findings also support a role of leptin in the process of fetal bone remodeling and brain development. Therefore, it is of interest to explore the physiology of leptin in early life, as well as those factors that may perturb the balance of the hormone with pathological consequences in terms of confining an increased risk for disease in later life. This review aims to summarize reported findings concerning the role of leptin in early life, as well as the association of fetal, maternal and placental factors with leptin levels, while attempting to speculate mechanisms through which these factors may influence the risk for developing chronic diseases in later life.

Leptin concentration in breast milk and its relationship to duration of lactation and hormonal status

BACKGROUND

Leptin, a hormone present in breast milk, is involved in energy regulation and metabolism. The objectives of this study were to assess leptin concentrations in breast milk during the first 180 days postpartum, and to determine the relationship between the concentrations of milk leptin and circulating hormone levels in lactating women.

METHODS

Between April 2005 and January 2006, blood and breast milk samples were collected from 160 breastfeeding women enrolled either in the first three days (n = 37; colostrum), days 4-14 (n = 27; transitional milk), days 15-30 (n = 16; early mature milk), days 31-90 (n = 37; mature milk) or days 91-180 (n = 43; late mature milk) postpartum. Milk and serum leptin levels were measured by immunoradiometric assay. Cortisol was measured by radioimmunoassay method. Serum insulin, estradiol, prolactin and thyroxine were measured by chemiluminescent immunometric method.

RESULTS

Leptin concentrations in breast milk were highest (3.28 +/- 0.41 ng/ml) in colostrum, decreased during the first 180 days of lactation, showing a significant inverse relation (r = -0.694, p < 0.001) with the days of lactation. Colostrum leptin concentrations correlated with maternal serum leptin (r = 0.425, p < 0.01), cortisol (r = 0.549, p < 0.01) and thyroxine (r = -0.530, p < 0.01). Mature milk leptin concentrations correlated with maternal serum leptin (r = 0.547, p < 0.001), insulin (r = 0.331, p < 0.05) and thyroxine (r = -0.329, p < 0.01). Serum leptin concentrations correlated with serum insulin (r = 0.648, p < 0.001), estradiol (r = 0.639, p < 0.001), prolactin (r = 0.530, p < 0.001) and thyroxine (r = -0.327, p < 0.05) concentrations during days 1-3 postpartum. During 15-180 postpartum days, serum leptin concentrations correlated with serum insulin (r = 0.271, p < 0.01), and thyroxine (r = -0.345, p < 0.001).

CONCLUSION

Leptin concentrations in breast milk decrease with time during lactation and show significant relationships with other maternal hormones.

Adiponectin and Leptin in Maternal Serum, Cord Blood, and Breast Milk

Background: The presence of the adipokines adiponectin and leptin in cord blood and placental and fetal tissues suggests a possible role in fetal development.

Methods: We measured concentrations of adiponectin and leptin in maternal serum, cord blood, and breast milk and examined their correlations within a large, population-based study. Between November 2000 and November 2001, we recruited all mothers and their newborns after delivery at the University of Ulm (Ulm, Germany). The current analysis included 766 mothers with available breast milk samples collected 6 weeks postpartum. Adipokine concentrations were measured with commercially available ELISAs (R&D Systems).

Results: Median adiponectin concentrations in maternal serum (n = 713), cord blood (n = 709), and breast milk (n = 766) were 8.6 mg/L, 30.6 mg/L, and 10.9 μg/L, respectively. Median leptin concentrations were 12.8 μg/L in maternal serum, 7.8 μg/L in cord blood, and 174.5 ng/L in breast milk. Whereas increases in leptin concentrations with increasing birth weight, birth weight according to gestational age, and ponderal index were statistically significant in cord blood (all P values &lt;0.0001), cord blood adiponectin was clearly related only to birth weight (P = 0.0004). Concentrations of both adipokines were moderately correlated in breast milk and maternal serum (both Spearman ρ values were 0.43; P &lt;0.0001).

Conclusions: Concentrations of adiponectin and leptin vary strongly in maternal serum, cord blood, and breast milk, with only moderate correlations between both adipokines in maternal serum and breast milk. The health implications of these patterns warrant further investigation.

Adiponectin, Adipocyte Fatty Acid Binding Protein, and Epidermal Fatty Acid Binding Protein: Proteins Newly Identified in Human Breast Milk

Background: Breastfeeding may protect children from developing metabolic syndrome and other diseases later in life. We investigated novel proteins in human breast milk that might play a role in this process.

Methods: We used ELISA to measure adiponectin, adipocyte and epidermal fatty acid binding proteins (AFABP, EFABP), and leptin concentrations in human breast milk obtained from 59 mothers 48 h after initiation of lactation. Using a questionnaire and medical records, we collected information about the mothers and newborns.

Results: Mean (SE) adiponectin concentrations in breast milk were 13.7 (0.8), range 3.9–30.4 μg/L; AFABP concentrations 26.7 (4.4), range 1.2–137.0 μg/L; EFABP concentrations 18.1 (1.4), range 0.8–47.0 μg/L; and leptin concentrations 0.50 (0.05), range 0–1.37 μg/L. We found a significant correlation between AFABP and EFABP concentrations (r = 0.593, P &lt;0.0001). Maternal EFABP concentrations were significantly higher in mothers who delivered boys than in those who delivered girls [21.7 (2.3) vs 15.4 (1.7) μg/L, P = 0.028] and correlated with newborn birth weight (r = 0.266, P = 0.045). Maternal leptin correlated with body weight before pregnancy (r = 0.272, P = 0.043) and at delivery (r = 0.370, P = 0.005), body mass index before pregnancy (r = 0.397, P = 0.003) and at delivery (r = 0.498, P &lt;0.0001), body weight gain during pregnancy (r = 0.267, P = 0.047), and newborn gestational age (r = 0.266, P = 0.048). Leptin was significantly lower in mothers who delivered preterm vs term babies [0.30 (0.09) vs 0.60 (0.05) ug/L, P = 0.026].

Conclusions: Concentrations of adiponectin, AFABP, and EFABP in human breast milk are related to nutritional variables of mothers and newborns and thus may play a role in the protective effects of breastfeeding.

Maternal BMI and serum leptin concentration of infants in the first year of life

AIM

To evaluate the relationship between serum leptin concentration in infants and infant and maternal BMI.

METHODS

75 healthy term infants aged 0-12 mo, 51 exclusively breastfed (BF) for at least 4 mo and 24 formula fed (FF), were included in a cross-sectional study. Weight, length and cranial circumference of infants and their mothers were measured, body mass index (BMI) was calculated using the formula weight (kg)/height (m2) and infant serum leptin concentration was determined.

RESULTS

A significant positive correlation between infant serum leptin concentration and maternal BMI was observed in BF infants (r = 0.389, p = 0.005), confirmed in a multiple regression model adjusted for infant age and infant BMI (beta = 0.065, p = 0.006), but not in FF infants. As regards the first 4 mo of life, we have already observed a positive correlation between infant serum leptin concentration and maternal BMI in BF infants (beta = 0.113, p = 0.005), but not in FF infants.

CONCLUSION

In BF infants, serum leptin concentration correlates positively with maternal BMI. Higher maternal BMI values might increase leptin levels in breast milk, and maternal adiposity could be involved in infant energy balance.

Leptin and its emerging role in children and adolescents

Leptin is an adipocyte-secreted hormone which plays a key role in energy homeostasis. Recent “proof of concept” studies involving leptin administration to humans support its critical role in regulating energy homeostasis, neuroendocrine and immune function as well as insulin resistance in states of energy/ caloric deprivation. Moreover, interventional studies in leptin deficient children and observational studies in normal girls and boys support a role for leptin as a permissive factor for the initiation of puberty in children. The potential clinical usefulness of leptin in several disease states in children and adolescents, including hypothalamic amenorrhea, eating disorders and syndromes of insulin resistance is still under investigation.

Correlation between blood and milk serum leptin in goats and growth of their offspring

Boer and Boer crossbred meat-type does were used in two experiments to determine whether goat milk serum contains leptin and to investigate possible correlations of milk and serum leptin in does and subsequent growth of their offspring. Blood and milk samples were collected within 2 h of kidding (d 0) from 20 (Exp. 1; spring) or 22 does (Exp. 2; the following fall). Blood milk samples were then collected again on d 0.5, 1, 3, 5, 7, 14, 21, 28, 35, 42, 49, and 56 (Exp. 1) or d 0.5, 1, 2, 3, 4, 5, 6, 7, 14, and 21 (Exp. 2). Body weights of kids were recorded on d 0, and BW of kids and does were recorded weekly beginning on d 7 (kids) or 21 (does), with BCS also recorded for does beginning on d 28 for Exp. 1 and on d 0.5, 1, 2, 3, 4, 5, 6, 7, 14, and 21 for Exp. 2. Leptin was detected in colostral milk and was influenced by days postpartum, decreasing (P < 0.001) over time with an average of 4.4 +/- 0.3 ng/mL (Exp. 1) and 18.1 +/- 1.0 ng/mL (Exp. 2) on d 0 compared with 1.0 +/- 0.3 ng/mL on d 56 (Exp. 1) and 2.9 +/- 0.2 ng/mL on d 21 (Exp. 2). Day postpartum and milk serum leptin were negatively correlated (P < 0.001) for Exp. 1 (r = -0.27) and Exp. 2 (r = -0.46). For Exp. 1 only, blood serum leptin tended (P = 0.09) to be influenced by day, with a weak positive correlation (r = 0.15; P < 0.02). Weak positive correlations (P < 0.01) were found between blood serum leptin and doe BCS (r = 0.42 in Exp. 1, and r = 0.13 in Exp. 2) and doe BW (r = 0.44 in Exp. 1, and r = 0.26 in Exp. 2), with the absence of a stronger relationship likely due in part to the short time period measured and the lack of significant changes in BCS and BW during that time. In conclusion, leptin was present in milk and blood serum of does, and blood serum leptin was weakly correlated with doe BW and BCS, but it was not related to kid BW. Therefore, further studies are needed to clarify the relationships involving milk and serum leptin in goats.