Fatty acid profiles of typical dietary lipids after gastrointestinal digestion and absorbtion: A combination study between in-vitro and in-vivo

Novel Nanoliposome Codelivered DHA and Anthocyanidin: Characterization, In Vitro Infant Digestibility, and Improved Cell Uptake

There are still many challenges in understanding the absorption and transport mechanism of liposomes in the gastrointestinal tract of infants, especially for liposome-coentrapped two or more substances. In this study, novel docosahexaenoic acid (DHA)-anthocyanidin-codelivery liposomes (DA-LPs) were fabricated and characterized, and their digestive and absorptive behaviors were evaluated using the in vitro infant digestive method combined with the Caco-2 cell model. The liposomal bilayer structure remained intact with the particles aggregated in simulated infant gastric fluid, while their phospholipid membrane underwent enzymatic lipolysis under simulated intestinal conditions. Compared to single substance-loaded liposomes (DHA- or anthocyanidin-loaded liposomes), the digested DA-LPs showed better cell viability, higher cellular uptake and membrane fluidity, and lower reactive oxygen species (ROS). It can be concluded that DA-LPs are promising carriers for simultaneously transporting hydrophobic and hydrophilic molecules and may be beneficial for improving nutrient absorption and alleviating intestinal stress oxidation.

An alternative solution for α-linolenic acid supplements: in vitro digestive properties of silkworm pupae oil in a pH-stat system

α-Linolenic acid (ALA) is recognised to have a regulatory effect on cardiovascular diseases. Due to the low bioavailability of linseed oil (LINO), which is the most common ALA supplement, it is necessary to find a replacement for ALA supplements that is more easily accepted by the human body. The content of ALA in silkworm pupae oil (SPO) is 32.60 ± 0.67%, and SPO can be substituted as a dietary lipid to meet the demand of the human body. In the present study, a pH-stat system was used to investigate the release degree of free fatty acids (FFAs) from SPO and construct a first-order kinetic model. Digestion experiments in vitro with different lipids showed that the maximum release FFA levels were SPO > SO (soybean oil) > LO (lard oil) > MSO (mulberry seed oil) > LINO, and the first-order kinetic apparent rate constants were LINO > SPO > LO > SO > MSO. Triacylglycerol (TAG) and fatty acid composition are the decisive factors in determining the level of lipid digestion. Therefore, the maximum level of FFAs released from SPO (84.34 ± 1.37%) was much higher than that of LINO (49.78 ± 0.52%) when the hydrolysis rates were 0.2114 s^-1 and 0.2249 s^-1, respectively. In addition, the smaller emulsion droplet size (609.24 ± 43.46 nm) and weaker surface charge (-17.93 ± 0.42 mV) also resulted in higher levels of SPO under in vitro digestion conditions. Meanwhile, due to low melting and crystallisation temperature, SPO is quickly absorbed by the human body. Overall, SPO can be used as a new alternative for ALA supplements based on its superior digestive properties.

Palm oil consumption and its repercussion on endogenous fatty acids distribution

The consumption of saturated lipids in combination with a sedentary lifestyle increases the risk of obesity and metabolic syndrome. However, the distribution of endogenous fatty acids (FA) after the consumption of saturated lipids and the connection between FA distribution and lipid metabolism-related genes relative expression have not been fully elucidated to date. In this study, we characterized FA profiles in the liver and visceral fats of Sprague Dawley (SD) rats fed with a high-palm-oil diet. The investigation showed that the levels of C16:0 and C18:1 (n-9) increased significantly (P < 0.05) in the liver of the high-palm-oil group (POG), while C16:1 (n-7) and C18:2 (n-6) accumulated markedly (P < 0.05) in the visceral fats of the control group (CN). A correlation analysis indicated a negative correlation between C16:0 and C16:1 (n-7) in the epididymal fat of POG. Our study also demonstrated that the intake of saturated lipids caused changes in lipid metabolism-related gene expression, especially stearoyl-CoA desaturase (SCD), which was upregulated at the third week but was inhibited in the subsequent weeks in the POG liver and perirenal fat. The SCD had a notable positive correlation with C16:1 (n-7) in the POG liver and perirenal fat but a significant negative correlation with C16:0 in the POG epididymal fat. In conclusion, the results of this study indicate that a high-C16:0 diet may result in adaptive SCD expression, and these findings may help to elucidate the effects of dietary fat on lipid metabolism.

Influence of different dietary oil consumption on nutrient malabsorption: An animal trial using Sprague Dawley rats

In the present study, the influences of five typical dietary oils (i.e., palm oil, PO; leaf lard oil, LO; rapeseed oil, RO; sunflower oil, SO; and linseed oil, LN) consumption on the nutrients malabsorption were studied using adult male Sprague Dawley rats. Results suggested that the C16:0 (24.534 ± 2.26% to 54.269 ± 1.28%) and C18:0 (18.433 ± 4.421% to 36.455 ± 3.316%) were the dominant fatty acids in fecal samples in different groups. After 6-week intervention by different dietary oils, the fecal moisture and water soluble protein content in PO group, the reducing sugar content in PO, LO, and RO groups were significantly increased compared with those in the control group (p < .05). Moreover, the Na, K, and Fe contents in LO group were all the highest among the all groups. These effects were probably due to the different fatty acids composition as illustrated in the correlation analysis results. The different effects were probably due to their distinct fatty acids composition as illustrated in the correlation analysis results. Results further indicated that the different dietary oils treatment, especially for the PO (SFAs, 43.17 ± 0.98%) and LO (SFAs, 36.44 ± 0.65%), increased the upstream inflammatory cytokine expression level in the Toll-like receptor signal pathway (i.e., TLR4 and MyD88), enhancing the gut permeability. This resulted in significant increase of serum lipopolysaccharide (LPS) levels (p < .05), which was closely connected with different metabolic diseases. The present study may provide basic understandings about different dietary oil enteral nutrition and their effects on gut health. PRACTICAL APPLICATIONS: The PO, LO, RO, SO, and LN are the five of the most typical dietary lipids in Asia countries, especially in China. They are the natural edible oils which are rich in C16:0, C18:0, C18:1, C18:2ω6, and C18:3ω3, respectively. The present study indicated that the different dietary lipid consumption may result in different dietary nutrients malabsorption, which are related with the dietary lipid fatty acid composition.

Impact of the Simulated Gastric Digestion Methodology on the In Vitro Intestinal Proteolysis and Lipolysis of Emulsion Gels

The aim of this work was to study the impact of the methodology of in vitro gastric digestion (i.e., in terms of motility exerted and presence of gastric emptying) and gel structure on the degree of intestinal proteolysis and lipolysis of emulsion gels stabilized by whey protein isolate. Emulsions were prepared at pH 4.0 and 7.0 using two homogenization pressures (500 and 1000 bar) and then the emulsions were gelled by heat treatment. These gels were characterized in terms of texture analysis, and then were subjected to one of the following gastric digestion methods: in vitro mechanical gastric system (IMGS) or in vitro gastric digestion in a stirred beaker (SBg). After gastric digestion, the samples were subjected to in vitro intestinal digestion in a stirred beaker (SBi). Hardness, cohesiveness, and chewiness were significantly higher in gels at pH 7.0. The degree of proteolysis was higher in samples digested by IMGS–SBi (7–21%) than SBg–SBi (3–5%), regardless of the gel’s pH. For SBg–SBi, the degree of proteolysis was not affected by pH, but when operating the IMGS, higher hydrolysis values were obtained for gels at pH 7.0 (15–21%) than pH 4.0 (7–13%). Additionally, the percentage of free fatty acids (%FFA) released was reduced by 47.9% in samples digested in the IMGS–SBi. For the methodology SBg–SBi, the %FFA was not affected by the pH, but in the IMGS, higher values were obtained for gels at pH 4.0 (28–30%) than pH 7.0 (15–19%). Our findings demonstrate the importance of choosing representative methods to simulate food digestion in the human gastrointestinal tract and their subsequent impact on nutrient bioaccessibility.

Lipidome is lipids regulator in gastrointestinal tract and it is a life collar in COVID-19: A review

The term lipidome is mentioned to the total amount of the lipids inside the biological cells. The lipid enters the human gastrointestinal tract through external source and internal source. The absorption pathway of lipids in the gastrointestinal tract has many ways; the 1st way, the lipid molecules are digested in the lumen before go through the enterocytes, digested products are re-esterified into complex lipid molecules. The 2nd way, the intracellular lipids are accumulated into lipoproteins (chylomicrons) which transport lipids throughout the whole body. The lipids are re-synthesis again inside the human body where the gastrointestinal lipids are: (1) Transferred into the endoplasmic reticulum; (2) Collected as lipoproteins such as chylomicrons; or (3) Stored as lipid droplets in the cytosol. The lipids play an important role in many stages of the viral replication cycle. The specific lipid change occurs during viral infection in advanced viral replication cycle. There are 47 lipids within 11 lipid classes were significantly disturbed after viral infection. The virus connects with blood-borne lipoproteins and apolipoprotein E to change viral infectivity. The viral interest is cholesterol- and lipid raft-dependent molecules. In conclusion, lipidome is important in gastrointestinal fat absorption and coronavirus disease 2019 (COVID-19) infection so lipidome is basic in gut metabolism and in COVID-19 infection success.

New insights into the digestion and bioavailability of a high-melting-temperature solid triacylglycerol fraction in bovine milk fat

Clarifying the health risks associated with the consumption of high-melting-temperature solid triacylglycerol (TAG) from milk fat has profound significance for the nutritional evaluation and development of new dairy products. Our previous work effectively separated butterfat into solid/liquid fractions (30S and 30L) at 30 °C and successfully reconstituted milk fat globules (MFGs) with these fractions. The current study examined the postprandial digestive and daily metabolic properties of a high-melting-temperature solid TAG fraction by performing animal experiments (rats) with 30S-reconstituted MFG emulsion gavage for 240 min and 30S-containing diet administration for 4 weeks. Compared to the consumption of whole butterfat, 30S consumption altered apolipoprotein levels and did not lead to dyslipidaemia in the rats. Conversely, 30S administration induced significant body weight loss by enhancing satiety signals (glucagon-like peptide 1, GLP-1; cholecystokinin, CCK; and peptide YY, PYY), increasing faecal losses, and upregulating the level of hepatic lipolysis-associated enzymes (hormone-sensitive lipase, HSL; adipose triglyceride lipase, ATGL; and protein kinase A, PKA). The 30S diet efficiently improved adipocyte hypertrophy and reduced fat accumulation by downregulating the level of acetyl-CoA carboxylase (ACC) in adipose tissue. This study is of relevance to nutrition science and the dairy industry.

Study of olive pomace antioxidant dietary fibre powder throughout gastrointestinal tract as multisource of phenolics, fatty acids and dietary fibre

Pulp-enriched powder (POPP) was obtained from olive pomace solid fraction, a derived from the new value chain established for olive by-products. As a multifunctional powder, POPP retains several bioactive compounds (fatty acids, dietary fibre and phenolics) under potential synergic interaction, even more, reactive throughout the digestion. So, in this study, the potential multifunctionality of POPP was evaluated after the gastrointestinal tract. A significant loss of phenolics occurred during oral digestion (62.48%). However, the potential role of dietary fibre as phenolics' carrier and its possible liberation in the stomach allowed recovering a significant amount of phenolics (77.11%) and a bioaccessibility index of at least 50% (mainly for tyrosol and its glucoside). POPP also provides high content of dietary fibre mainly insoluble fibre (69.68 g/100 g dry weight) linked to a substantial amount of bound phenolics (7.63 mg of gallic acid equivalents/g fibre dry weight), with a positive effect on the fatty acids bioaccessibility [decreased the saturated (5-6%) and facilitated the unsaturated fatty acids bioaccessibility (4-11%)]. PCA analysis became evident the negative effect of simulated gastrointestinal digestion upon POPP as mainly linked to phenolics' loss. Despite all negative effects of the simulated digestion on POPP bioactive composition, phenolics and unsaturated fatty acids showed to be bioaccessible in significant amount, and the amount of bound phenolics associated to fibre retained in the colon have the potential to exert gut health benefits.

Effect of the ingestion of vegetable oils associated with energy-restricted normofat diet on intestinal microbiota and permeability in overweight women

Previous studies suggest that the type of dietary fatty acid may modulate the intestinal bacterial ecosystem. However, this effect is still inconclusive. Thus, the aim of this study was to investigate the effect of the intake of vegetable oils rich in different types of fatty acids, associated with energy-restricted normofat diets, on the composition of intestinal microbiota and permeability, on LPS concentrations, and fecal short chain fatty acids and pH. This was a 9 consecutive weeks (±5 days), randomized, parallel, double-blind clinical trial. Overweight women received daily breakfast containing 25 mL of one of the test oils: soybean oil (n = 17), extra virgin olive oil (n = 19) or coconut oil (n = 16). Blood, fecal and urine samples were collected on the first and last day of the experiment for the analysis of the variables of interest. The consumption of the three oils did not affect the diversity and relative abundance of intestinal bacteria. We observed an increase in bacterial richness estimated by the Chao 1 index, and a reduction in the concentration of isovaleric fatty acid in the group that ingested soybean oil. Paracellular and transcellular permeability increased after the ingestion of extra virgin olive oil and coconut oil. However, LPS concentrations remained unchanged. The intake of different types of fatty acids associated with the energy-restricted normofat diet modestly affected the intestinal microbiota and permeability, without resulting in metabolic endotoxemia in overweight women.

Evaluating the appropriate oral lipid tolerance test model for investigating plasma triglyceride elevation in mice

The oral lipid tolerance test (OLTT) has been known to assess intestinal fat metabolism and whole-body lipid metabolism, but rodent models for OLTT are not yet established. Differences in OLTT methodology preclude the generation of definitive results, which may cause some confusion about the anti-hypertriglyceridemia effects of the test materials. To standardize and generate more appropriate methodology for the OLTT, we examined the effects of mice strain, dietary lipid sources, fasting period, and gender on lipid-induced hypertriglyceridemia in mice. First, lipid-induced hypertriglyceridemia was more strongly observed in male ddY mice than in C57BL/6N or ICR mice. Second, the administration of olive and soybean oils remarkably represented lipid-induced hypertriglyceridemia. Third, fasting period before the OLTT largely affected the plasma triglyceride elevation. Fasting for 12 h, but less than 48 h, provoked lipid-induced hypertriglyceridemia. Fourth, we explored the suppressive effects of epigallocatechin gallate (EGCG), a green tea polyphenol, on lipid-induced hypertriglyceridemia. The administration of 100 mg/kg of EGCG suppressed lipid-induced hypertriglyceridemia and intestinal lipase activity. Fifth, EGCG-induced suppressive effects were observed after lipid-induced hypertriglyceridemia was observed in male mice, but not in female mice. Lastly, lipid-induced hypertriglyceridemia could be more effectively induced in mice fed a high-fat diet for 1 week before the OLTT. These findings indicate that male ddY mice after 12 h fasting displayed marked lipid-induced hypertriglyceridemia in response to soybean oil. Hence, the defined experiment condition may be a more appropriate OLTT model for evaluating lipid-induced hypertriglyceridemia.

In Vitro Gastrointestinal Digestion of Palm Olein and Palm Stearin-in-Water Emulsions with Different Physical States and Fat Contents

The impacts of lipid physical state and content on lipid digestion behavior were investigated using 4 and 20% palm olein-in-water emulsions (4% PO and 20% PO) and 4 and 20% palm stearin-in-water emulsions (4% PS and 20% PS). The changes of lipid physical state, particle size, and microstructure during gastrointestinal digestion; the free fatty acid (FFA) released in the intestinal phase; and the fatty acid composition of micellar phases were investigated. After gastric digestion, all emulsions underwent flocculation and coalescence, with 20% PS showing the most extensive aggregation. During intestinal digestion, the FFA release rate and level decreased as the lipid content increased from 4 to 20%, with 4% PO presenting the highest digestion rate and extent. Besides, the solid fat in 4% PS and 20% PS decreased and increased the maximum lipid digestibility, respectively. These results highlighted the combined roles of lipid physical state and content in modulating dietary lipid digestion.

Study of the In Vitro Digestion of Olive Oil Enriched or Not with Antioxidant Phenolic Compounds. Relationships between Bioaccessibility of Main Components of Different Oils and Their Composition

The changes provoked by in vitro digestion in the lipids of olive oil enriched or not with different phenolic compounds were studied by proton nuclear magnetic resonance (¹H NMR) and solid phase microextraction followed by gas chromatography/mass spectrometry (SPME-GC/MS). These changes were compared with those provoked in the lipids of corn oil and of virgin flaxseed oil submitted to the same digestive conditions. Lipolysis and oxidation were the two reactions under consideration. The bioaccessibility of main and minor components of olive oil, of phenolic compounds added, and of compounds formed as consequence of the oxidation, if any, were matters of attention. Enrichment of olive oil with antioxidant phenolic compounds does not affect the extent of lipolysis, but reduces the oxidation degree to minimum values or avoids it almost entirely. The in vitro bioaccessibility of nutritional and bioactive compounds was greater in the olive oil digestate than in those of other oils, whereas that of compounds formed in oxidation was minimal, if any. Very close quantitative relationships were found between the composition of the oils in main components and their in vitro bioaccessibility. These relationships, some of which have predictive value, can help to design lipid diets for different nutritional purposes.

Comparative Study of the Oxidation Stability of High Oleic Oils and Palm Oil during Thermal Treatment

For the controversy still existed about the oxidation stability of the high oleic oils compared with palm oil (PO), this study was aimed to explore the possible reason causing the controversies. Total polar compounds (TPC) was used to evaluate the oxidation stability of oils. Results showed there exist two kinds of lineal changes about the content of total polar compounds (TPC) in each oil, which were closely linked with the fatty acid composition and the tocochromanols content. The possible influence of the initial quality of oils also should be considered. The TPC of high oleic peanut oil (HOPO), high oleic sunflower oil (HOSO), high oleic rapeseed oil (HORO) and PO increased slowly at the initial period mainly owing to the antioxidation of tocochromanols, then sharply after 24, 48, 36 and 72 h respectively, when tocochromanols in each oil almost reduced below the detection limit. After that, the major factor would be fatty acids, particularly PUFA. It showed that the major tocochromanols in different oils (e.g. α, γ-tocotrienols in PO, α, γ-tocopherols in HORO and HOPO, and α-tocopherols in HOSO), could impose the main effects of inhibiting the TPC generation in the initial thermal treatment. The TPC in HORO significantly increased after 84 hours of heat process, which might be caused by the higher content of the polyunsaturated fatty acids (PUFA) (i.e. C18:2 and C18:3). However, the content of the saturated fatty acid (SFA) did not show statistically significant change during the thermal treatment.

Different dietary lipid consumption affects the serum lipid profiles, colonic short chain fatty acid composition and the gut health of Sprague Dawley rats

Palm oil (PO), leaf lard oil (LO), rapeseed oil (RO), sunflower oil (SO), and linseed oil (LINO) are the five of the most typical dietary lipids, while few studies have explored and compared their influences on the serum lipid profiles, colonic short chain fatty acids (SCFAs) composition and colon health of Sprague Dawley (SD) rats. Results from the present work showed that PO and LO groups showed significantly higher serum TG and TC level compared with Ctrl group, whereas, the LDL-C/HDL-C and TC/HDL-C ratio were significantly lower in the RO, SO and LINO groups. Different dietary lipid consumption (15% of the normal diet) decreased the colonic SCFAs concentration. The saturated fatty acid (SFA) was negatively correlated, while unsaturated fatty acid (UFA)/SFA ratio was positively correlated, with colonic isobutyric acid concentration. The C18:2ω6 and ω3 fatty acids were positively correlated with colonic butyric acid and isovaleric acid concentration, respectively. Results also demonstrated that PO and LO could decrease the colon villus length and crypt depth, and led to colon injury, which might be due to their high SFAs content. Moreover, results suggested that PO and LO could specifically up-regulate the colon inflammation related gene expression levels and down-regulate the Muc2 expression levels, thus, imposing negative impact on the mucus layers. The present study could provide some information for nutritional evaluation about these dietary lipids.

Proximate Composition and Nutritional Profile of Rainbow Trout (Oncorhynchus mykiss) Heads and Skipjack tuna (Katsuwonus Pelamis) Heads

In order to evaluate the application potential of rainbow trout (Oncorhynchus mykiss) heads and skipjack tuna (Katsuwonus pelamis) heads; proximate composition, amino acids, fatty acids, carnosine, and anserine contents were analyzed in this study. Rainbow trout heads showed significantly higher protein (29.31 g/100 g FW, FW is abbreviation of fresh weight) and lipid (6.03 g/100 g FW) contents than skipjack tuna heads (18.47 g/100 g FW protein and 4.83 g/100 g FW lipid) (p < 0.05). Rainbow trout heads and skipjack tuna heads exhibited similar amino acid composition. Essential amino acids constituted more than 40% of total amino acids in both rainbow trout head and skipjack tuna head. The fatty acid profile was different between rainbow trout heads and skipjack tuna heads. Rainbow trout heads mainly contained 38.64% polyunsaturated fatty acids (PUFAs) and 38.57% monounsaturated fatty acids (MUFAs), whereas skipjack tuna heads mainly contained 54.46% saturated fatty acids (SFAs). Skipjack tuna heads contained 4563 mg/kg FW anserine and 1761 mg/kg FW carnosine, which were both significantly higher than those of rainbow trout heads (p < 0.05). These results demonstrate that both rainbow trout heads and skipjack tuna heads may be used as materials for recycling high-quality protein. Meanwhile, rainbow trout heads can be used to extract oil with high contents of unsaturated fatty acids, while skipjack tuna heads may be a source for obtaining carnosine and anserine.