Signe Bruun

Human milk contains macronutrients possibly affecting infant and early childhood growth. Most studies suggest a sex-specific difference in macronutrient levels in favor of males, with a higher energy content from fat, lactose, and protein. Further, macronutrient levels may differ according to mixed or exclusive breastfeeding; however, the literature is inconsistent. Our aim was to investigate sex-specific differences in macronutrient content in exclusively breastfed infants in a Danish child cohort, and whether macronutrient levels differed between exclusive or mixed (breast and formula) breastfeeding. Participants were part of the prospective birth cohort Odense Child Cohort. Baseline characteristics were obtained from medical records. Weekly SMS questions were sent to the mothers until the cessation of breastfeeding, asking whether they were breastfeeding and/or formula feeding. Mothers delivered a milk sample at the planned 3–4-month examination of the infant. Macronutrient analyses were performed on 182 samples using mid-infrared transmission spectroscopy (Miris Human milk Analyzer). We included 150 mother–infant dyads with both macronutrient analysis, and SMS data on breastfeeding. Baseline characteristics did not differ according to sex. The median interquartile range (IQR) infant age at the time of sampling was 4.1 (3.7–4.5) months. A total of 39 males and 38 females were exclusively breastfed at the time of milk sampling, while 36 males and 37 females were mixed-fed. We found no significant sex-specific differences in macronutrients among exclusively breastfed infants. The median (IQR) levels for males and females, respectively, were; protein, 0.85 g/100 mL (0.77, 0.90), and 0.82 g/100 mL (0.80, 0.90), p = 0.91; lactose, 7.83 g/100 mL (7.70, 7.95), and 7.73 g/100 mL (7.53, 7.90), p = 0.17; fat, 3.23 g/100 mL (2.07, 4.37), and 3.07 g/100 mL (2.10, 3.60), p = 0.34; energy, 65.5 kcal/100 mL (54.17, 77.00), and 63 kcal/100 mL (56.00, 69.33), p = 0.13. Further, we found no significant differences in macronutrient content in human milk samples from exclusively versus mixed-feeding mothers either prior and after adjusting for confounders, p > 0.36. This study does not confirm the previous findings of sex-specific differences in macronutrients in human milk. It is still unknown if sex-specific formula products tailored to meet possible sex-specific requirements can optimize child growth. Further research on this topic is needed.

Breastfed infants have different growth patterns to formula-fed infants and are less likely to develop obesity later in life. Nesfatin-1 is an anorexigenic adipokine that was discovered in human milk more than a decade ago, and its role in infant appetite regulation is not clear. Our aim was to describe nesfatin-1 levels in human milk collected 3–4 months postpartum, associations with infant anthropometry, and factors (maternal pre-pregnancy body mass index (mBMI), high weight gain during pregnancy, milk fat, and energy content) possibly influencing nesfatin-1 levels. We hypothesized that nesfatin-1 levels in mother’s milk would differ for infants that were large (high weight-for-age Z-score (WAZ)) or small (low WAZ) at the time of milk sample collection. We used enzyme-linked immunosorbent assay to detect the nesfatin-1 concentration in milk samples from mothers to high WAZ (n = 50) and low WAZ (n = 50) infants. We investigated associations between nesfatin-1 levels and infant anthropometry at 3–4 months of age and growth since birth, using linear regression adjusted for mBMI, birth weight, infant sex, and exclusivity of breastfeeding. We found no difference in nesfatin-1 levels between the two groups and no association with infant anthropometry, even after adjusting for potential confounders. However, high nesfatin-1 levels were correlated with low mBMI. Future research should investigate serum nesfatin-1 level in both mothers, infants and associations with growth in breastfed children.

Blood pressure (BP) and blood lipid profile (BLP) have been shown to track from childhood into adulthood, and n-3 long-chain polyunsaturated fatty acids (LC-PUFAs) in breast milk have been suggested as mediators of the beneficial long-term effect of breastfeeding on BP and BLP. We aimed to investigate associations between n-3 LC-PUFA content in breast milk at 4 months postpartum and offspring BP and BLP in early life. BP and BLP were measured at 4, 18, and 36 months. Statistical analyses were sex-stratified and adjusted for gestational age, maternal pre-pregnancy body mass index (BMI), and maternal educational level. Based on 336 mother-child dyads, high n-3 LC-PUFA in breast milk was inversely associated with systolic and diastolic BP in boys at 4 months (β = −20.0 (95% CI = −33.4, −6.7), p = 0.004 and β = −10.2 (95% CI = −19.8, −0.5), p = 0.039, respectively); inversely associated with HDL cholesterol, and directly associated with triglyceride in girls at 4 months (β = −0.7 (95% CI = −1.1, −0.3), p = 0.001 and β = 3.1 (95% CI = 1.0, 5.2), p = 0.005, respectively). Associations observed at the later time points were non-significant. Furthermore, we observed sex-specific changes over time in both size and direction of the associations. Our results indicate that early intake of n-3 LC-PUFA can affect early development in cardiometabolic factors such as BP and BLP in a sex-specific manner. Follow-up and further investigation in later childhood is planned.

Regulation of appetite and food intake is partly regulated by N-acylethanolamine lipids oleoylethanolamide (OEA), stearoylethanolamide (SEA), and palmitoylethanolamide (PEA), which induce satiety through endogenous formation in the small intestine upon feeding, but also when orally or systemic administered. OEA, SEA, and PEA are present in human milk, and we hypothesized that the content of OEA, SEA, and PEA in mother’s milk differed for infants being heavy (high weight-for-age Z-score (WAZ)) or light (low WAZ) at time of milk sample collection. Ultra-high performance liquid chromatography-mass spectrometry was used to determine the concentration of OEA, SEA, and PEA in milk samples collected four months postpartum from mothers to high (n = 50) or low (n = 50) WAZ infants. Associations between OEA, SEA, and PEA concentration and infant anthropometry at four months of age as well as growth from birth were investigated using linear and logistic regression analyses, adjusted for birth weight, early infant formula supplementation, and maternal pre-pregnancy body mass index. Mean OEA, SEA, and PEA concentrations were lower in the high compared to the low WAZ group (all p < 0.02), and a higher concentration of SEA was associated with lower anthropometric measures, e.g., triceps skinfold thickness (mm) (β = −2.235, 95% CI = −4.04, −0.43, p = 0.016), and weight gain per day since birth (g) (β = −8.169, 95% CI = −15.26, −1.08, p = 0.024). This raises the possibility, that the content of satiety factors OEA, SEA, and PEA in human milk may affect infant growth.

Objectives: Osteopontin (OPN) is a multifunctional protein expressed in many cell types, tissues and body fluids with the highest concentrations found in milk; significantly higher in human than in bovine milk. Intervention studies have indicated beneficial effects of supplementing infant formula with bovine OPN. In this multicenter study, we determined the OPN content in human milk samples from 629 Chinese, Danish, Japanese and Korean mothers.Methods: At each study site, milk samples were collected and analyzed for OPN and protein concentration using ELISA and infrared spectroscopy, respectively.Results: A total of 829 milk samples from 629 women were included. When delivering the first sample, mean maternal age was 31.4 years (SD 4.0), and median infant age was 13.4 weeks (interquartile range 4.6–17.9). The median OPN concentration varied across sites; from 99.7 mg/L in Danish, 185.0 mg/L in Japanese, 216.2 mg/L in Korean to 266.2 mg/L in Chinese mothers (P < 0.001), corresponding to 1.3%, 2.4%, 1.8% and 2.7% of the total protein content (OPN/protein%) (P < 0.05), respectively. Based on 75 Chinese and 33 Japanese mothers delivering more than 1 sample, multilevel (mixed model) linear regression analysis showed a decrease in OPN concentration with infant age (β = (−11.3), 95% confidence interval (CI) = (−13.9) to (−8.8) and β = (−2.1), 95% CI = (−3.2) to (−0.9), respectively).Conclusions: In this large multicenter study, we observed statistically significant differences in the OPN concentration and the OPN/protein% in human milk samples between countries. Based on mothers delivering more than 1 sample, a significant decrease within the lactation period was observed.

Background: Studies on prevalence and effects of breastfeeding call for reliable and precise data collection to optimize infant nutrition, growth, and health. Data on breastfeeding and infant nutrition are at risk of, for example, recall bias or social desirability bias. Objective: The aim of the present analysis was to compare data on infant nutrition, that is, breastfeeding, use of infant formula, and introduction to complementary foods, obtained by four different methods. We assumed that weekly short message service (SMS) questions were the most reliable method, to which the other methods were compared. Design: The study population was part of the Odense Child Cohort. The four methods used were: (a) self-administered questionnaire 3 months postpartum, (b) self-administered questionnaire 18 months postpartum, (c) registrations from health visitors visiting the families several times within the first year of life, and (d) weekly SMS questions introduced shortly after birth. Results: In total, 639 singleton mothers with data from all four methods were included. The proportion of mothers initiating breastfeeding varied from 86% to 97%, the mean duration of exclusive breastfeeding from 12 to 19 weeks, and the mean age when introduced to complementary foods from 19 to 21 weeks. The mean duration of any breastfeeding was 33 weeks across methods. Conclusions: Compared with the weekly SMS questions, the self-administered questionnaires and the health visitors' reports resulted in a greater proportion of mothers with an unknown breastfeeding status, a longer duration of exclusive breastfeeding and later introduction to complementary foods, while the duration of any breastfeeding did not differ.

Objectives: Free glutamic acid has an appetite‐regulating effect and studies with infant formula have suggested that free amino acids (FAA), especially glutamic acid, can downregulate intake. The content of glutamic acid and glutamine is high in breast milk but varies considerably between mothers. The aim was to investigate whether maternal anthropometry was associated with the content of the FAA glutamic acid or glutamine in breast milk and whether there was a negative association between these FAA and current size or early infant growth in fully breastfed infants.Methods: From a subgroup of 78 mothers, of which 50 were fully breast feeding, from the Odense Child Cohort breast milk samples were collected 4 months after birth and analyzed for FAA. Information regarding breastfeeding status and infant weight and length was also recorded.Results: There was a large variation in the concentration of the FAAs between mothers. Glutamic acid was positively correlated with mother's prepregnancy weight and height (P ⩽ 0.028), but not body mass index. There was no negative correlation between the 2 FAA and infant weight or body mass index. Infant length at 4 months was, however, positively associated with glutamine, (P = 0.013) but the correlation was attenuated when controlling for birth length (P = 0.089).Conclusions: The hypothesis that a high content of glutamic acid and glutamine in breast milk could downregulate milk intake to a degree affecting early growth could not be confirmed. Maternal factors associated with the level of these FAA in milk and the potential effect on the infant should be investigated further.

Aim: Our aim was to use text message questions to obtain prospective, real‐time data on exclusive and partial breastfeeding and introduction to complementary foods in a Danish birth cohort. We also wanted to identify factors influencing breastfeeding initiation and cessation.Methods: This study formed part of the Odense Child Cohort and focused on mothers who gave birth to full‐term singletons between April and October 2012. They received the same three to five questions, about breastfeeding, infant formula and introduction to complementary food, three days after birth and then at weekly intervals.Results: We recruited 499 mothers, and the response rate to the first of the weekly questions was ≥89.4% during the study. Three days after birth, 96.7% of mothers were breastfeeding, 61.2% exclusively and 30.2% partially, and 26 weeks after birth 60.2% of mothers were breastfeeding, 1.1% exclusively. Complementary food was introduced at an average age of 20 weeks. Breastfeeding cessation was associated with maternal smoking, lower maternal age and supplementation with infant formula in the first days after birth (all p < 0.05).Conclusion: Most mothers initiated breastfeeding, but only 1.1% were exclusively breastfeeding at 26 weeks. Text messaging resulted in high response rates and was a feasible data collection method.