Palmitic acid is absorbed as sn-2 monopalmitin from milk and formula with rearranged triacylglycerols and results in increased plasma triglyceride sn-2 and cholesteryl ester palmitate in piglets

Acceptability of "High sn-2" Infant Formula in Non-Breast Fed Healthy Term Infants Regarding Gastrointestinal Tolerability by Both Parents and Pediatrician: An Open-Label Pilot Study in the Gulf Cooperation Council (GCC) Countries

Recent studies have highlighted the positive impact of high sn-2 formulas on gastrointestinal (GI) tolerance. We assessed the GI tolerance, acceptability, and safety of high sn-2 infant formula among non-breastfed healthy term infants in the Gulf countries. A multicenter observational study was conducted on 227 healthy-term infants who were prescribed high sn-2 palmitate infant formula and received a minimum of two formula feedings per day for the past two weeks prior to the study's initiation. The number of stools per day decreased significantly from a median of four (interquartile range [IQR] = 4) at baseline to 3.0 (2) stools per day at the end of follow-up (p = 0.015). The percentage of stool amount changed significantly, where 61.2% and 33.7% of the infants had an amount of 25-50% of the diaper and >50% of the diaper, respectively (p < 0.001) at the end of the follow-up. Similarly, the percentage of hard stool decreased significantly from 17.4% at baseline to 0.4% of the population at week 12 (p < 0.00). The prevalence of colic and abdominal distention declined from 21.4% and 39.9% at baseline to 2.9% and 9.4% at week 12, respectively (p < 0.05). The same decline was observed in abdominal distension and regurgitation score (p < 0.05).

Addition of Dairy Lipids and Probiotic Lactobacillus fermentum in Infant Formulas Modulates Proteolysis and Lipolysis With Moderate Consequences on Gut Physiology and Metabolism in Yucatan Piglets

Breast milk is the gold standard in neonatal nutrition, but most infants are fed infant formulas in which lipids are usually of plant origin. The addition of dairy lipids and/or milk fat globule membrane extracts in formulas improves their composition with beneficial consequences on protein and lipid digestion. The probiotic Lactobacillus fermentum (Lf) was reported to reduce transit time in rat pups, which may also improve digestion. This study aimed to investigate the effects of the addition of dairy lipids in formulas, with or without Lf, on protein and lipid digestion and on gut physiology and metabolism. Piglets were suckled from postnatal days 2 to 28, with formulas containing either plant lipids (PL), a half-half mixture of plant and dairy lipids (DL), or this mixture supplemented with Lf (DL+Lf). At day 28, piglets were euthanized 90 min after their last feeding. Microstructure of digesta did not differ among formulas. Gastric proteolysis was increased (P < 0.01) in DL and DL+Lf (21.9 ± 2.1 and 22.6 ± 1.3%, respectively) compared with PL (17.3 ± 0.6%) and the residual proportion of gastric intact caseins decreased (p < 0.01) in DL+Lf (5.4 ± 2.5%) compared with PL and DL (10.6 ± 3.1% and 21.8 ± 6.8%, respectively). Peptide diversity in ileum and colon digesta was lower in PL compared to DL and DL+Lf. DL and DL+Lf displayed an increased (p < 0.01) proportion of diacylglycerol/cholesterol in jejunum and ileum digesta compared to PL and tended (p = 0.07) to have lower triglyceride/total lipid ratio in ileum DL+Lf (0.019 ± 0.003) as compared to PL (0.045 ± 0.011). The percentage of endocrine tissue and the number of islets in the pancreas were decreased (p < 0.05) in DL+Lf compared with DL. DL+Lf displayed a beneficial effect on host defenses [increased goblet cell density in jejunum (p < 0.05)] and a trophic effect [increased duodenal (p = 0.09) and jejunal (p < 0.05) weights]. Altogether, our results demonstrate that the addition of dairy lipids and probiotic Lf in infant formula modulated protein and lipid digestion, with consequences on lipid profile and with beneficial, although moderate, physiological effects.

Metabolic transition of milk triacylglycerol synthesis in response to varying levels of palmitate in porcine mammary epithelial cells

BACKGROUND

Milk in mammals is a key source of lipids for offspring, providing both critical energy and essential fatty acids. For lactating sows, palmitic acid is one of the most abundant fatty acids in milk, providing 10~12% of the suckling pig total dietary energy supply. However, the effects of exogenous palmitic acid on milk fat synthesis in sow mammary glands are not well-known. In this study, we investigated the effects of palmitic acid on lipogenic genes in porcine mammary epithelial cells (pMECs) to explore the role of exogenous palmitic acid in mediating milk triacylglycerols (TAG) synthesis.

METHODS

Porcine mammary epithelial cells were cultured for 24 h in the presence of different concentrations of palmitate (0, 25, 50, 100, 200, 400, and 600 μM). The effect of palmitate on cell viability was tested via MTT assay. Intracellular lipid accumulation was measured through Oil Red O staining, and TAG levels were quantified by enzymatic colorimetric methods. Expression of genes and proteins involved in milk fat biosynthesis were assayed with quantitative real-time polymerase chain reaction (qPCR) and Western blotting, respectively.

RESULTS

Incubation with palmitate promoted cellular lipid synthesis in a dose-dependent manner, as reflected by the increased TAG content and enhanced formation of cytosolic lipid droplets. The increased lipid synthesis by palmitate was probably attributable to the upregulated mRNA expression of genes associated with milk fat biosynthesis, including long-chain fatty acid uptake (LPL, CD36), intracellular activation and transport (ACSL3, FABP3), TAG synthesis (GPAM, AGPAT6, DGAT1), lipid droplet formation (PLIN2), and regulation of transcription (PPARγ). Western blot analysis of CD36 and DGAT1 proteins confirmed the increased lipid synthesis with increasing incubation of palmitate. However, the genes involved in fatty acid de novo synthesis (ACACA, FASN), fatty acid desaturation (SCD), and regulation of transcription (SREBP1, INSIG1) were inversely affected by incubation with increasing concentrations of palmitate. Western blot analysis of ACACA protein confirmed this decrease associated with increasing levels of palmitate.

CONCLUSIONS

Results from this study suggest that palmitate stimulated the cytosolic TAG accumulation in pMECs, probably by promoting lipogenic genes and proteins that are involved in lipid synthesis. However, addition of palmitate decreased the fatty acid de novo synthesis in pMECs.

Preparation of human milk fat analogue by enzymatic interesterification reaction using palm stearin and fish oil

Palm stearin fractionate (PSF), obtained from palm stearin by further fractionation with solvents and n-3 polyunsaturated fatty acids (n-3 PUFA) rich fish oil (FO) were subjected to interesterification at 1:1, 1:2, 1:3, 2:1 and 3:1 substrate molar ratio and catalyzed by lipase from Thermomyces lanuginosa for obtaining a product with triacylglycerol (TAG) structure similar to that of human milk fat (HMF). The parameters (molar ratio and time) of the interesterification reaction were standardized. The temperature of 60 °C and enzyme concentration of 10 % (w/w) were kept fixed as these parameters were previously optimized. The reactions were carried out in a stirred tank reactor equipped with a magnetic stirrer for 6, 12, 18 and 24 h. The blends were analyzed for fatty acid (FA) composition of both total FAs and those at the sn-2 position after pancreatic lipase hydrolysis. All the blended products were subjected to melting point determination and free fatty acid content. Finally, blend of PSF and FO at 2:1 molar ratio with 69.70 % palmitic acid (PA) content and 12 h of reaction produced the desired product with 75.98 % of PA at sn-2 position, 0.27 % arachidonic acid (AA), 3.43 % eicosapentaenoic acid (EPA) and 4.25 % docosahexaenoic acid (DHA) and with melting point of 42 °C. This study portrayed a successful preparation of TAG containing unique FA composition i.e. ≥ 70 % of the PA, by weight, were esterified at the sn-2 position which could be used in infant formulation with health benefits of n-3 PUFAs.

Comparison of Chemical and Enzymatic Interesterification of Fully Hydrogenated Soybean Oil and Walnut Oil to Produce a Fat Base with Adequate Nutritional and Physical Characteristics

The optimal physical, chemical and nutritional properties of natural lipids depend on the structure and composition of triacylglycerols. However, they are not always mutually compatible. Lipid modification is a good way to give them specific functionalities, increase their oxidative stability, or improve their nutritional value. As such, chemical and enzymatic interesterification may be used to modify them and produce structured lipids. In accordance, the aim of this study is to compare chemical and enzymatic interesterification of binary blends of fully hydrogenated soybean oil and walnut oil, using sodium methoxide or Lipozyme TL IM, respectively, to produce a fat base with adequate nutritional and physical characteristics. Three different mass ratios of fully hydrogenated soybean oil and walnut oil blends (20:80, 40:60 and 60:40) were interesterified and evaluated. Total interesterification was determined by the stabilization of the solid fat content. Chemical reaction of the 20:80 blend was completed in 10 min and of the 40:60 and 60:40 blends in 15 min. Enzymatically interesterified blends were stabilized in 120 min at all of the mass ratios. Complete interesterification significantly reduced the solid fat content of the blends at any composition. Chemical and enzymatically interesterified fully hydrogenated blend of soybean and walnut oil at mass ratio of 40:60 showed the plastic curve of an all-purpose- -type shortening rich in polyunsaturated fatty acids, with a high linolenic acid (C18:3n3) content and with zero trans-fatty acids.

Dietary triacylglycerol structure and its role in infant nutrition

Human milk TG are a remarkable example of stereo-specific positioning of fatty acids with structures that are highly conserved and unusual. Not only does human milk contain high amounts of fat and 16:0, but ~70% of the 16:0 is esterified at the TG stereo-specifically numbered (sn)-2 position, with preferential positioning of 18:1(n-9) and 18:2(n-6) at the TG sn-1,3 positions. The milk TG structures and digestive lipases combine to enable efficient digestion and absorption of 16:0 by conserving 16:0 in sn-2 monoacylglycerols, which are absorbed, reassembled, and secreted in plasma conserving the original milk TG configuration; these studies are reviewed in this article. The reason why the mammary gland invests in enzymes to provide the infant with 20-25% milk fatty acids as 16:0 rather than selecting against 16:0 is unknown, yet likely has a purpose given the mammary gland capacity for 10:0, 12:0, and 14:0 synthesis. Recent advances in the development-, tissue-, and species-specific activity of enzymes of TG synthesis and knowledge that dietary TG structures are maintained postabsorption suggest that the purpose of the milk TG structures is more sophisticated than simply avoiding 16:0 malabsorption. The overall aim is to expand consideration of fatty acids in the infant diet from a simple view of average fatty acid compositions to the complex lipids and molecular structures in which fatty acids are provided to tissues during early life and the biology through which the unique features of human milk enable the infant to grow and thrive on a high-fat, high-saturated-fat milk diet.

Effects of stereospecific positioning of fatty acids in triacylglycerol structures in native and randomized fats: a review of their nutritional implications

Most studies on lipid lowering diets have focused on the total content of saturated, polyunsaturated and monounsaturated fatty acids. However, the distribution of these fatty acids on the triacylglycerol (TAG) molecule and the molecular TAG species generated by this stereospecificity are characteristic for various native dietary TAGs. Fat randomization or interesterification is a process involving the positional redistribution of fatty acids, which leads to the generation of new TAG molecular species. A comparison between native and randomized TAGs is the subject of this review with regards to the role of stereospecificity of fatty acids in metabolic processing and effects on fasting lipids and postprandial lipemia. The positioning of unsaturated versus saturated fatty acids in the sn-2 position of TAGs indicate differences in early metabolic processing and postprandial clearance, which may explain modulatory effects on atherogenecity and thrombogenecity. Both human and animal studies are discussed with implications for human health.