Interactions between cortisol and lipids in human milk

Abstract

Background: Human breast milk is one of the key early postnatal biological exposures for the developing child. It includes bioactive compounds, such as cortisol and fatty acids, which may be linked via the mother's lipid metabolism. Methods: This study investigated the associations between cortisol and lipids in human milk at the infant age of 2.5 months. Human milk cortisol concentrations were measured using luminescence immunoassay, and two groups of milks (n = 50 each) were formed based on either high (> 10 nmol/L) or low (< 3 nmol/L) cortisol levels. Lipids, as fatty acid content and composition of neutral (triacylglycerol-rich) and polar (phospholipid-rich) lipids, were measured with gas chromatography. The samples originated from the FinnBrain Birth Cohort Study. Results: The percentage of phospholipid-rich lipids of total lipids was 33.08% ± 1.33%. In triacylglycerol-rich lipids, high cortisol level in milk was associated with higher lauric (12:0, mass % and mg/mL), myristic (14:0, mass % and mg/mL), eicosenoic (20:1n − 9, mass %), docosenoic (22:1n − 9, mass %, and mg/mL) acids, and to lower palmitic acid (16:0, mass %) compared with low cortisol levels in milk. In phospholipid-rich lipids, high cortisol level was associated with higher myristic (14:0, mass %) and docosenoic (22:1n − 9, mass %) acids. After adjusting for pre-pregnancy BMI and sampling time by linear regression, the milk cortisol remained a significant predictor for lauric and myristic acids in triacylglycerolrich lipids, and myristic and docosenoic acid in phospholipid-rich lipids (β = 0.23 to 0.38 and p < 0.05 for each). Conclusions: This study revealed certain significant associations between milk cortisol and the fatty acid composition of human milk, indicating that cortisol might be one of the factors affecting the origin of the lipids in human milk.

Factors Influencing Cortisol Concentrations in Breastmilk and Its Associations with Breastmilk Composition and Infant Development in the First Six Months of Lactation

“…In contrast, a study from the Netherlands reported that breastmilk cortisol increased from two to 12 weeks of lactation [ 20 , 41 ]. Cortisol levels observed in our study were higher than those observed in other studies [ 6 , 10 , 15 , 19 , 21 , 22 , 23 , 24 , 41 , 42 ], but lower than those reported in some studies [ 7 , 20 , 43 ]. Moreover, we observed significant differences between cortisol levels between the season of sample collection—higher levels of cortisol were observed in samples collected during the autumn-winter season in the first month of lactation, but in the sixth month of lactation in the spring-summer season.…”

“…According to the lactational programming hypothesis, they affect metabolic and neurobiological development, and, in consequence, offspring phenotype and behavior [ 13 , 14 , 15 , 16 ]. Studies investigated maternal psychological [ 10 , 15 , 17 , 18 , 19 , 20 , 21 , 22 ], socio-demographic [ 7 , 10 , 18 , 23 ], or anthropometric [ 3 , 10 , 24 ] determinants of breastmilk GCs levels provide inconclusive results. Similarly, results regarding the mode of delivery [ 5 , 10 ], preterm birth [ 6 , 10 , 17 ] or seasonal variations [ 10 , 23 ] were inconsistent.…”

“…Previous primate and human studies showed that breastmilk cortisol was associated with infant temperament and fear reactivity, but the direction of those associations was inconsistent and sometimes sex-specific [ 13 , 15 , 19 , 25 , 26 ]. Additionally, due to the regulation of macronutrient metabolism and immune system breastmilk, cortisol may affect breastmilk composition [ 9 , 21 , 24 , 26 , 28 , 29 ], but these results are also unclear, thus further studies are necessary.…”

Human milk: From complex tailored nutrition to bioactive impact on child cognition and behavior

“…The same group further showed that variations in these milk components were collectively associated with differences in the microbial community structures of infant feces and the abundance of specific taxa (Pace et al 2021). Finally, Linderborg et al (2020), showed that higher milk cortisol concentrations are related to a greater abundance of lauric and myristic fatty acids. These correlational studies suggest that individual milk components are inter-related and potentially influence one another.…”

“…Recent studies show correlations between different human milk components, including amino acids, sugars, lipids, proteins, hormones, HMOs, and milk microbiota (Gómez-Gallego et al 2018;Linderborg et al 2020;Moossavi et al 2019a;Williams et al 2017;Pace et al 2021). Gómez-Gallego et al (2018), showed that lactate, creatine, proline, lacto-N-fucopentaose 1, 2′-fucosyllactose and very low-density lipoprotein particles were positively correlated with gammaproteobacteria and negatively correlated with alphaproteobacteria, betaproteobacteria and bacilli.…”