Co-Evolution of Breast Milk Lipid Signaling and Thermogenic Adipose Tissue

Breastfeeding is a unique and defining behavior of mammals and has a fundamental role in nourishing offspring by supplying a lipid-rich product that is utilized to generate heat and metabolic fuel. Heat generation from lipids is a feature of newborn mammals and is mediated by the uncoupling of mitochondrial respiration in specific fat depots. Breastfeeding and thermogenic adipose tissue have a shared evolutionary history: both have evolved in the course of homeothermy evolution; breastfeeding mammals are termed “thermolipials”, meaning “animals with warm fat”. Beyond its heat-producing capacity, thermogenic adipose tissue is also necessary for proper lipid metabolism and determines adiposity in offspring. Recent advances have demonstrated that lipid metabolism in infants is orchestrated by breast milk lipid signals, which establish mother-to-child signaling and control metabolic development in the infant. Breastfeeding rates are declining worldwide, and are paralleled by an alarming increase in childhood obesity, which at least in part may have its roots in the impaired metabolic control by breast milk lipid signals.

Cannabinoids accumulate in mouse breast milk and differentially regulate lipid signaling molecules involved in infant development

Maternal cannabis use during lactation may expose developing infants to cannabinoids (CBs) such as tetrahydrocannabinol (THC) and cannabidiol (CBD). CBs modulate lipid signaling molecules in the central nervous system in age- and cell-dependent ways, but their influence on the lipid composition of breastmilk has yet to be established. This study investigates the effects of THC, CBD, or their combination on milk lipids by analyzing the stomach contents of CD1 mouse pups that have been nursed by dams injected with CBs on postnatal days (PND) 1 -10 collected 2 hours after the last injection on PND10. HPLC/MS/MS was used to identify and quantify over 80 endogenous lipid species and cannabinoids in pup stomach contents. We show that CBs differentially accumulate in milk, lead to widespread decreases in free fatty acids, decreases in N-acyl methionine species, increases N-linoleoyl species, as well as modulate levels of endogenous CBs (eCBs) AEA, 2-AG, and their structural congeners. Our data indicate the passage of CBs to pups through breast milk and that maternal CB exposure alters breast milk lipid compositions.

Homogenized and pasteurized human milk: lipid profile and effect as a supplement in the enteral diet of Wistar rats

The retention of human milk fat in nasogastric probes of infusion pumps can be observed during the feed of infants unable to suck at the mother’s breast. The lack of homogenization of human milk could contribute to the fat holding. Therefore, the present study evaluated (i) the influence of homogenization on milk fat retaining in infant feeding probes and (ii) the in vivo effect of the homogenization on lipid absorption by Wistar rats. The animals were fed with human milk treated following two processing conditions, i.e., pasteurized and homogenized-pasteurized. The animals were randomly subdivided into four experimental groups: water-fed (control), pasteurized milk, homogenized-pasteurized milk, and pasteurized-skimmed milk. The results of food consumption, mass body gain, corporate metrics, and plasma blood levels of total cholesterol did not show any difference (p<0.05) among the three types of human milk used in the experiments. The liver, intestine, and intra-abdominal adipose tissue of the four groups of animals presented normal and healthy histology. The composition of fatty acids in the brain tissue of animals fed with homogenized human milk increased when compared with the groups fed with non-homogenized human milk. These values were 11.08% higher for arachidonic acids, 6.59% for docosahexaenoic, and 47.92% for nervous acids. The ingestion of homogenized human milk promoted higher absorption of milk nutrients. Therefore, the addition of the homogenization stage in human milk processing could be an alternative to reduce fat retention in probes and to improve the lipids’ absorption in the body.

Milk Fat Globule Membrane Proteome and Micronutrients in the Milk Lipid Fraction: Insights into Milk Bioactive Compounds

Milk lipids are composed of milk fat globules (MFGs) surrounded by the milk fat globule membrane (MFGM). MFGM protects MFGs from coalescence and enzymatic degradation. The milk lipid fraction is a “natural solvent” for macronutrients such as phospholipids, proteins and cholesterol, and micronutrients such as minerals and vitamins. The research focused largely on the polar lipids of MFGM, given their wide bioactive properties. In this review we discussed (i) the composition of MFGM proteome and its variations among species and phases of lactation and (ii) the micronutrient content of human and cow’s milk lipid fraction. The major MFGM proteins are shared among species, but the molecular function and protein expression of MFGM proteins vary among species and phases of lactation. The main minerals in the milk lipid fraction are iron, zinc, copper and calcium, whereas the major vitamins are vitamin A, β-carotene, riboflavin and α-tocopherol. The update and the combination of this knowledge could lead to the exploitation of the MFGM proteome and the milk lipid fraction at nutritional, biological or technological levels. An example is the design of innovative and value-added products, such as MFGM-supplemented infant formulas.

FATTY ACID PROFILE OF NON-CONFORMING POOLED HUMAN MILK AS AFFECTED BY THE PROCESSING AND STORAGE CONDITIONS

The fatty acid's contents of non-conform pooled human milk can be affected by different processing and storage operational conditions. Besides, the knowledge of changes in the human milk fatty acid profile can help indicate its use in a given storage period, according to each newborn's specific need. Thus, in the present work, changes in the fatty acid profiles of three types of human milk (raw; pasteurized at 62.5 °C for 30 min; homogenized at 40 oC for 30 s followed by pasteurization) were studied during storage for six months in a freezer at -18 oC. Large variations were observed in the concentrations of polyunsaturated fatty acids, particularly of docosahexaenoic acid, with a reduction of almost 50% of its total. Palmitic and stearic acid contents also changed according to the conditions of processing and storage. Correlations between the decrease of long fatty acid chains and the increase of medium and short chains were verified. Thus, we observe that operational conditions of processing and storing change human milk lipid profile, with some nutritional losses.

Exposure to per- and polyfluoroalkyl substances associates with altered lipid profile of breast milk

BackgroundChemical composition of human breast milk is highly variable inter- and intra-individually. Environmental factors are suspected to partly explain the compositional variation, however, their impact on breast milk composition is currently poorly understood.ObjectivesWe sought (1) to define the impact of maternal exposure to per- and polyfluoroalkyl substances (PFAS) on lipid composition of human breast milk, and (2) to study the combined impact of maternal PFAS exposure and breast milk lipid composition on the growth of the infants.MethodsIn a mother-infant study (n=44) we measured the levels of PFAS and lipids in maternal serum and conducted lipidomics analysis of breast milk at birth and at 3 months of infant age, by using ultra high performance liquid chromatography combined with quadrupole-time-of-flight mass spectrometry. Maternal diet was studied by a validated food frequency questionnaire.ResultsPFAS levels were inversely associated with total lipid levels in the breast milk collected at birth. In the high exposure group, the ratio of acylated saturated and polyunsaturated fatty acids in triacylglycerols was increased. Moreover, high exposure to PFAS associated with the altered phospholipid composition, which was indicative of unfavorable increase in the size of milk fat globules. These changes in the milk lipid composition were further associated with slower infant growth and with elevated intestinal inflammatory markers.DiscussionOur data suggest that the maternal exposure to PFAS impacts the nutritional quality of the breast milk, which, in turn, may have detrimental impact on the health and growth of the children later in life.