Differences in Postprandial Lipid Response to Breast- or Formula-feeding in 8-Week-Old Infants

The effects of breastfeeding and formula feeding on the metabolic factors and the expression level of obesity and diabetes-predisposing genes in healthy infants

Diabetes mellitus (DM) and obesity are common illnesses characterized by glucose metabolism issues and excessive weight gain. Breastfeeding is the best way to feed a newborn up to 6 months old and it has been shown to reduce the risk of diabetes and obesity later in life due to its nutritional properties. The purpose of this study was to investigate the effects of breastfeeding, formula feeding, and formula-plus breastfeeding (mix-feeding) on the anthropometric indices, metabolic variables, and the expression level of obesity and diabetes-predisposing genes of healthy infants. A total of 150 healthy infants were enrolled in this cross-sectional study. All infants (aged 24 months) were divided into three groups based on the type of feeding, breastfeeding, formula feeding, and mix-feeding. The anthropometric indices, glycemic indexes, lipid profile, and the expression levels of acetyl-coenzyme A carboxylase beta (ACACB), brain-derived neurotrophic factor (BDNF), liver X receptor α (LXR-α), peroxisome proliferator-activated receptor γ (PPAR-γ), and phosphatase and tensin homolog (PTEN) genes were measured in all infants using reverse transcription-polymerase chain reaction (RT-PCR) method. The anthropometric indices including weight, height, head circumference, insulin, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were lower in the breastfeeding infants in comparison to other groups. As well, the expression level of the ACACB gene was significantly downregulated in breastfeeding infants, while the PPAR-γ gene was significantly upregulated, but the expression levels of LXR- α, PTEN and BDNF did not change significantly across groups. Breastfeeding compared to formula feeding had positive effects on anthropometric indices, metabolic variables, and diabetes-predisposing genes.

Perspective: Moving Toward Desirable Linoleic Acid Content in Infant Formula

Infant formula should provide the appropriate nutrients and adequate energy to facilitate healthy infant growth and development. If conclusive data on quantitative nutrient requirements are not available, the composition of human milk (HM) can provide some initial guidance on the infant formula composition. This paper provides a narrative review of the current knowledge, unresolved questions, and future research needs in the area of HM fatty acid (FA) composition, with a particular focus on exploring appropriate intake levels of the essential FA linoleic acid (LA) in infant formula. The paper highlights a clear gap in clinical evidence as to the impact of LA levels in HM or formula on infant outcomes, such as growth, development, and long-term health. The available preclinical information suggests potential disadvantages of high LA intake in the early postnatal period. We recommend performing well-designed clinical intervention trials to create clarity on optimal levels of LA to achieve positive impacts on both short-term growth and development and long-term functional health outcomes.

An early-life diet containing large phospholipid-coated lipid globules programmes later-life postabsorptive lipid trafficking in high-fat diet- but not in low-fat diet-fed mice

Feeding mice in early life a diet containing an experimental infant milk formula (Nuturis®; eIMF), with a lipid structure similar to human milk, transiently lowered body weight (BW) and fat mass gain upon Western-style diet later in life, when compared with mice fed diets based on control IMF (cIMF). We tested the hypothesis that early-life eIMF feeding alters the absorption or the postabsorptive trafficking of dietary lipids in later life. Male C57BL/6JOlaHsd mice were fed eIMF/cIMF from postnatal day 16-42, followed by low- (LFD, American Institute of Nutrition (AIN)-93 G, 7 wt% fat) or high-fat diet (HFD, D12451, 24 wt% fat) until day 63-70. Lipid absorption rate and tissue concentrations were determined after intragastric administration of stable isotope (2H or 13C) labelled lipids in separate groups. Lipid enrichments in plasma and tissues were analysed using GC-MS. The rate of triolein absorption was similar between eIMF and cIMF fed LFD: 3·2 (sd 1·8) and 3·9 (sd 2·1) and HFD: 2·6 (sd 1·7) and 3·8 (sd 3·0) % dose/ml per h. Postabsorptive lipid trafficking, that is, concentrations of absorbed lipids in tissues, was similar in the eIMF and cIMF groups after LFD. Tissue levels of absorbed TAG after HFD feeding were lower in heart (-42 %) and liver (-46 %), and higher in muscle (+81 %, all P < 0·05) in eIMF-fed mice. In conclusion, early-life IMF diet affected postabsorptive trafficking of absorbed lipids after HFD, but not LFD. Changes in postabsorptive lipid trafficking could underlie the observed lower BW and body fat accumulation in later life upon a persistent long-term obesogenic challenge.

Infant Rhesus Macaque Brain α-Tocopherol Stereoisomer Profile Is Differentially Impacted by the Source of α-Tocopherol in Infant Formula

BACKGROUND

α-Tocopherol (αT) in its natural form [2'R, 4'R, 8'R αT (RRR-αT)] is more bioactive than synthetic α-tocopherol (all rac-αT). All rac-αT is widely used in infant formulas, but its accretion in formula-fed infant brain is unknown.

OBJECTIVE

We sought to compare αT and stereoisomer status in infant rhesus macaques (Macaca mulatta) fed infant formula (RRR-αT or all rac-αT) with a reference group fed a mixed diet of breast milk and maternal diet.

METHODS

From 1 d after birth until 6 mo of age, infants (n = 23) were either nursery reared and exclusively fed 1 of 2 formulas by staff personnel or were community housed with their mothers and consumed a mixed reference diet of breast milk (69 mL/d at 6 mo) transitioning to monkey diet at ∼2 mo (MF; n = 8). Formulas contained either 21 μmol RRR-αT/L (NAT-F; n = 8) or 30 μmol all rac-αT/L (SYN-F; n = 7). Total αT and αT stereoisomers were analyzed in breast milk at 2, 4, and 6 mo and in monkey plasma and liver and 6 brain regions at 6 mo of age. α-Tocopherol transfer protein (α-TTP), lipoprotein αT, and urinary α-carboxyethyl-hydroxychroman (α-CEHC) were measured. One-way ANOVA with Tukey's post-hoc test was used for analysis.

RESULTS

At study termination, plasma, liver, lipoprotein, and brain total αT did not differ between groups. However, the NAT-F-fed group had higher RRR-αT than the SYN-F-fed group (P < 0.01) and the MF group (P < 0.0001) in plasma (1.7- and 2.7-fold) and brain (1.5- and 2.5-fold). Synthetic αT 2R stereoisomers (SYNTH-2R) were generally 3- and 7-fold lower in brain regions of the NAT-F group compared with those of the SYN-F and MF groups (P < 0.05). SYNTH-2R stereoisomers were 2-fold higher in MF than SYN-F (P < 0.0001). The plasma percentage of SYNTH-2R was negatively correlated with the brain percentage of RRR-αT (r = -0.99, P < 0.0001). Brain αT profiles were not explained by α-TTP mRNA or protein expression. Urine α-CEHC was 3 times higher in the NAT-F than in the MF group (P < 0.01).

CONCLUSIONS

Consumption of infant formulas with natural (NAT-F) compared with synthetic (SYN-F) αT differentially impacted brain αT stereoisomer profiles in infant rhesus macaques. Future studies should assess the functional implications of αT stereoisomer profiles on brain health.

Metabolic phenotype of breast-fed infants, and infants fed standard formula or bovine MFGM supplemented formula: a randomized controlled trial

Formula-fed (FF) infants exhibit a different metabolic profile than breast-fed (BF) infants. Two potential mechanisms are the higher protein level in formula compared with breast milk and the removal of the milk fat and associated milk fat globule membranes (MFGM) during production of infant formula. To determine whether MFGM may impact metabolism, formula-fed infants were randomly assigned to receive either an MFGM isolate-supplemented experimental formula (EF) or a standard formula (SF) from 2 until 6 months and compared with a BF reference group. Infants consuming EF had higher levels of fatty acid oxidation products compared to infants consuming SF. Although the protein level in the study formula was approximately 12 g/L (lower than most commercial formulas), a metabolic difference between FF and BF remained such that FF infants had higher levels of amino acid catabolism by-products and a low efficiency of amino acid clearance (preference for protein metabolism). BF infants had higher levels of fatty acid oxidation products (preference for fat metabolism). These unique, energy substrate-driven metabolic outcomes did not persist after diet was shifted to weaning foods and appeared to be disrupted by complementary feeding. Our results suggest that MFGM may have a role in directing infant metabolism.