Brain α-Tocopherol Concentration and Stereoisomer Profile Alter Hippocampal Gene Expression in Weanling Mice.

BACKGROUND: Alpha-tocopherol (αT), the bioactive constituent of vitamin E, is essential for fertility and neurological development. Synthetic αT (8 stereoisomers; all rac-αT) is added to infant formula at higher concentrations than natural αT (RRR-αT only) to adjust for bio-potency differences, but its effects on brain development are poorly understood. OBJECTIVES: The objective was to determine the impact of bio-potency-adjusted dietary all rac-αT versus RRR-αT, fed to dams, on the hippocampal gene expression in weanling mice. METHODS: Male/female pairs of C57BL/6J mice were fed AIN 93-G containing RRR-αT (NAT) or all rac-αT (SYN) at 37.5 or 75 IU/kg (n = 10/group) throughout gestation and lactation. Male pups were euthanized at 21 days. Half the brain was evaluated for the αT concentration and stereoisomer distribution. The hippocampus was dissected from the other half, and RNA was extracted and sequenced. Milk αT was analyzed in separate dams. RESULTS: A total of 797 differentially expressed genes (DEGs) were identified in the hippocampi across the 4 dietary groups, at a false discovery rate of 10%. Comparing the NAT-37.5 group to the NAT-75 group or the SYN-37.5 group to the SYN-75 group, small differences in brain αT concentrations (10%; P < 0.05) led to subtle changes (<10%) in gene expression of 600 (NAT) or 487 genes (SYN), which were statistically significant. Marked differences in brain αT stereoisomer profiles (P < 0.0001) had a small effect on fewer genes (NAT-37.5 vs. SYN-37.5, 179; NAT-75 vs. SYN-75, 182). Most of the DEGs were involved in transcription regulation and synapse formation. A network analysis constructed around known vitamin E interacting proteins (VIPs) revealed a group of 32 DEGs between NAT-37.5 vs. SYN-37.5, explained by expression of the gene for the VIP, protein kinase C zeta (Pkcz). CONCLUSIONS: In weanling mouse hippocampi, a network of genes involved in transcription regulation and synapse formation was differentially affected by dam diet αT concentration and source: all rac-αT or RRR-αT.

Fat composition in infant formula contributes to the severity of necrotising enterocolitis.

Necrotising enterocolitis (NEC) is a devastating disease that typically affects formula-fed premature infants, suggesting that dietary components may influence disease pathogenesis. TAG are the major fat components of infant formula, and their digestion requires pancreatic lipases, which may be naturally deficient in premature neonates. We hypothesise that NEC develops partly from the accumulation of incompletely digested long-chain TAG-containing unsaturated fatty acids within the intestinal epithelial cells, leading to oxidative stress and enterocyte damage. We further hypothesise that the administration of a formula that contains reduced TAG ('pre-digested fat') that do not require lipase action may reduce NEC severity. To test these hypotheses, we induced NEC in neonatal mice using three different fat formulations, namely 'standard fat', 'pre-digested fat' or 'very low fat', and determined that mice fed 'standard fat' developed severe NEC, which was significantly reduced in mice fed 'pre-digested fat' or 'very low fat'. The expression level of the critical fat-digesting enzyme carboxyl ester lipase was significantly lower in the newborn compared with older pups, leading to impaired fat digestion. The accumulation of mal-digested fat resulted in the significant accumulation of fat droplets within the intestinal epithelium of the distal ileum, resulting in the generation of reactive oxygen species and intestinal inflammation. Strikingly, these changes were prevented in pups fed 'pre-digested fat' or 'very low fat' formulas. These findings suggest that nutritional formula containing a pre-digested fat system may overcome the natural lipase deficiency of the premature gut, and serve as a novel approach to prevent NEC.

Supplementation with RRR- or all-rac-α-Tocopherol Differentially Affects the α-Tocopherol Stereoisomer Profile in the Milk and Plasma of Lactating Women.

Background: The naturally occurring α-tocopherol stereoisomer RRR-α-tocopherol is known to be more bioactive than synthetic α-tocopherol (all-rac-α-tocopherol). However, the influence of this difference on the α-tocopherol stereoisomer profile of human milk is not understood.Objective: We investigated whether supplemental RRR-α-tocopherol or all-rac-α-tocopherol differentially affected the distribution of α-tocopherol stereoisomers in milk and plasma from lactating women.Methods: Eighty-nine lactating women aged 19-40 y and with a body mass index (in kg/m2) ≤30 were randomly assigned at 4-6 wk postpartum to receive a daily supplement containing 45.5 mg all-rac-α-tocopherol acetate (ARAC), 22.8 mg all-rac-α-tocopherol acetate + 20.1 mg RRR-α-tocopherol (MIX), or 40.2 mg RRR-α-tocopherol (RRR). Milk and plasma were analyzed for α-tocopherol structural isomers and α-tocopherol stereoisomers at baseline and after 6 wk supplementation with the use of chiral HPLC.Results: There were no significant treatment group or time-dependent changes in milk or plasma α, γ, or δ-tocopherol. RRR-α-tocopherol was the most abundant stereoisomer in both milk and plasma in each group. Supplementation changed both milk and plasma percentage RRR-α-tocopherol (RRR > MIX > ARAC) (P < 0.05) and percentage non-RRR-α-tocopherol (ARAC > MIX > RRR) (P < 0.05). In the RRR group, percentage RRR-α-tocopherol increased in milk (mean ± SEM: 78% ± 2.3% compared with 82% ± 1.7%) (P < 0.05) and plasma (mean ± SEM: 77% ± 1.8% compared with 87% ± 1%) (P < 0.05). In contrast, the percentage RRR-α-tocopherol decreased in the MIX and ARAC groups (MIX, P < 0.05; ARAC, P < 0.0001), and percentage non-RRR-α-tocopherol stereoisomers increased (MIX, P < 0.05; ARAC, P < 0.0001) commensurate with an accumulation of 2S-α-tocopherol stereoisomers (P < 0.05) in both milk and plasma. Milk and plasma RRR-α-tocopherol was positively correlated at baseline (r = 0.67; P < 0.0001) and 6 wk (r = 0.80; P < 0.0001).Conclusion: The α-tocopherol supplementation strategy differentially affected the α-tocopherol milk and plasma stereoisomer profile in lactating women. RRR-α-tocopherol increased milk and plasma percentage RRR-α-tocopherol, whereas all-rac-α-tocopherol acetate reduced these percentages. Because RRR-α-tocopherol is the most bioactive stereoisomer, investigating the impact of supplement-driven changes in the milk α-tocopherol stereoisomer profile on the α-tocopherol status of breastfed infants is warranted.

Direct determination of methionine sulfoxide in milk proteins by enzyme hydrolysis/high-performance liquid chromatography.

A direct and simultaneous HPLC/UV determination of methionine and methionine sulfoxide in enzyme-hydrolyzed milk proteins is described. Protein hydrolysis is accomplished by a three-enzyme (pronase, leucine aminopeptidase, prolidase) 20-h/37 degrees C digestion. A gradient elution reversed-phase HPLC system with UV detection at 214 nm and 280 nm is then used to determine the quantitative releases of methionine sulfoxide, methionine, tyrosine, and tryptophan. The ease of methionine oxidation by a wide variety of oxidants, coupled with the quantitative release of both methionine and its sulfoxide by the three-enzyme hydrolysis, renders the approach valuable for identifying oxidized milk proteins. The relatively simple method proved accurate and precise in its application to commercial milk products, finding methionine sulfoxide levels as high as 74% of the total methionine.

Comparison of Brain Development in Sow-Reared and Artificially Reared Piglets.

INTRODUCTION: Provision of adequate nutrients is critical for proper growth and development of the neonate, yet the impact of breastfeeding versus formula feeding on neural maturation has to be fully determined. Using the piglet as a model for the human infant, our objective was to compare neurodevelopment of piglets that were either sow-reared (SR) or artificially reared (AR) in an artificial setting. METHODS: Over a 25-day feeding study, piglets (1.5 ± 0.2 kg initial bodyweight) were either SR (n = 10) with ad libitum intake or AR (n = 29) receiving an infant formula modified to mimic the nutritional profile and intake pattern of sow's milk. At study conclusion, piglets were subjected to a standardized set of magnetic resonance imaging (MRI) procedures to quantify structure and composition of the brain. RESULTS: Diffusion tensor imaging, an MRI sequence that characterizes brain microstructure, revealed that SR piglets had greater (P < 0.05) average white matter (WM) (generated from a piglet specific brain atlas) fractional anisotropy (FA), and lower (P < 0.05) mean and radial and axial diffusivity values compared with AR piglets, suggesting differences in WM organization. Voxel-based morphometric analysis, a measure of white and gray matter (GM) volumes concentrations, revealed differences (P < 0.05) in bilateral development of GM clusters in the cortical brain regions of the AR piglets compared with SR piglets. Region of interest analysis revealed larger (P < 0.05) whole brain volumes in SR animals compared with AR, and certain subcortical regions to be larger (P < 0.05) as a percentage of whole brain volume in AR piglets compared with SR animals. Quantification of brain metabolites using magnetic resonance spectroscopy revealed SR piglets had higher (P < 0.05) concentrations of myo-inositol, glycerophosphocholine + phosphocholine, and creatine + phosphocreatine compared with AR piglets. However, glutamate + glutamine levels were higher (P < 0.05) in AR piglets when compared with SR animals. CONCLUSION: Overall, increases in brain metabolite concentrations, coupled with greater FA values in WM tracts and volume differences in GM of specific brain regions, suggest differences in myelin development and cell proliferation in SR versus AR piglets.

Exploratory Metabolomic Analyses Reveal Compounds Correlated with Lutein Concentration in Frontal Cortex, Hippocampus, and Occipital Cortex of Human Infant Brain.

Lutein is a dietary carotenoid well known for its role as an antioxidant in the macula, and recent reports implicate a role for lutein in cognitive function. Lutein is the dominant carotenoid in both pediatric and geriatric brain tissue. In addition, cognitive function in older adults correlated with macular and postmortem brain lutein concentrations. Furthermore, lutein was found to preferentially accumulate in the infant brain in comparison to other carotenoids that are predominant in diet. While lutein is consistently related to cognitive function, the mechanisms by which lutein may influence cognition are not clear. In an effort to identify potential mechanisms through which lutein might influence neurodevelopment, an exploratory study relating metabolite signatures and lutein was completed. Post-mortem metabolomic analyses were performed on human infant brain tissues in three regions important for learning and memory: the frontal cortex, hippocampus, and occipital cortex. Metabolomic profiles were compared to lutein concentration, and correlations were identified and reported here. A total of 1276 correlations were carried out across all brain regions. Of 427 metabolites analyzed, 257 were metabolites of known identity. Unidentified metabolite correlations (510) were excluded. In addition, moderate correlations with xenobiotic relationships (2) or those driven by single outliers (3) were excluded from further study. Lutein concentrations correlated with lipid pathway metabolites, energy pathway metabolites, brain osmolytes, amino acid neurotransmitters, and the antioxidant homocarnosine. These correlations were often brain region-specific. Revealing relationships between lutein and metabolic pathways may help identify potential candidates on which to complete further analyses and may shed light on important roles of lutein in the human brain during development.

Glycemic and insulinemic responses of nondiabetic healthy adult subjects to an experimental acid-induced viscosity complex incorporated into a glucose beverage.

OBJECTIVE: An acid-induced-viscosity (I-V) complex containing alginate, citrate, and insoluble calcium was incorporated into a glucose-based beverage. We hypothesized that the acid I-V beverage would become viscous in the stomach (due to the solubilization of calcium and its interaction with alginate and citrate) and would blunt glycemia. METHODS: Thirty subjects were used in a double-masked, placebo-controlled crossover study evaluating the acid I-V complex. The placebo was a glucose-based beverage that had a similar total dietary fiber level and initial viscosity (Control). After a 12-h overnight fast, serum glucose and insulin were monitored over a 3-h postprandial period. RESULTS: The postprandial mean peak incremental change from baseline in serum glucose tended (P < 0.06) to be lower for the acid I-V product. The net incremental area under the curve (AUC) for serum glucose was reduced 75% (P < 0.01) by the acid I-V product, which was due mainly to an increased undershoot. The mean peak incremental change from baseline in serum insulin was higher (P < 0.05) for the acid I-V product. Net incremental AUC for serum insulin did not differ (P > 0.20) between products. CONCLUSIONS: Results of this study suggested that the acid I-V complex may attenuate the postprandial glycemic response to a glucose challenge in healthy subjects.

Inclusion of guar gum and alginate into a crispy bar improves postprandial glycemia in humans.

A novel induced viscosity fiber (IVF) crispy bar was formulated with the viscous dietary fibers alginate and guar gum. To evaluate the glycemic response and gastrointestinal tolerance to IVF crispy bars, nondiabetic healthy adult subjects (n = 48) were studied in a randomized, double-masked, crossover design. The control crispy bars and IVF crispy bars were identical except for the 2 dietary fibers contained in the experimental (IVF) bars. After an overnight fast, subjects consumed test bars containing 50 g carbohydrate. Their capillary blood glucose response was determined for 180 min postprandially. When subjects consumed IVF, the incremental blood glucose excursions were reduced (P < 0.05) at 15, 30, 45, and 120 min. At 180 min, the subjects' blood glucose concentration was maintained above the basal blood glucose concentration for both bars. Compared with controls, the incremental peak blood glucose concentration was reduced (P < 0.001) 30% when subjects consumed IVF. When subjects consumed IVF, the positive incremental area under the curve for glucose was reduced (P < 0.01) by 33% compared with controls. In the 24-h postprandial period after each treatment, the frequency and intensity of gastrointestinal tolerance symptoms did not differ. In conclusion, compared with a control crispy bar, the IVF crispy bar attenuated the postprandial glycemic excursion without gastrointestinal intolerance in healthy adult subjects.