Lipid composition modulates the intestine digestion rate and serum lipid status of different edible oils: a combination of in vitro and in vivo studies

Excessive oil absorption and maillard reaction products in fried muscle foods: Formation mechanisms, potential health risks and mitigation strategies

Fried muscle foods are popular among consumers for their golden color, fried flavor, and crispy exterior paired with a tender interior. However, physicochemical reactions occurring during frying lead to the formation of harmful components. This review focuses on the formation mechanisms of excessive oil and Maillard reaction products (advanced glycation end products, and heterocyclic amines) in fried muscle foods including protein oxidation, starch gelatinization, and generation of carbonyls and free radicals. The gastrointestinal digestion, absorption, and potential health risks of these components are discussed. It also summarizes the measures to inhibit oil absorption in four ways, including reducing initial moisture content, controlling moisture migration, reducing frying oil usage, and reducing interfacial tension between oil and food. Finally, it reviews mitigation strategies of Maillard reaction products from two aspects: reducing precursors, and trapping intermediates. This review may help produce healthier fried muscle foods.

Palm oil as part of a high-fat diet: advances and challenges, or possible risks of pathology?

Nutritional status disorders have the most significant impact on the development of cardiovascular and oncologic diseases; therefore, the interest in the study of palm oil as among the leading components of nutrition has been increasing. The data examined in this review were sourced from the Scopus, SCIE (Web of Science), PubMed and PubMed Central, MEDLINE, CAPlus/SciFinder, and Embase databases; experts in the field; bibliographies; and abstracts from review analyses from the past 15 years. This review summarizes recent research data focusing on the quantitative and qualitative composition of nutrition of modern humans; concepts of the relationship between high-fat diets and disorders of insulin functioning and transport and metabolism of fatty acids; analyses of data regarding the palmitic acid (16:0) to oleic acid (18:1) ratio; and the effect of diet based on palm oil consumption on cardiovascular risk factors and lipid and lipoprotein levels. Several studies suggest a potential vector contributing to the transmission of maternal, high-fat-diet-induced, addictive-like behaviors and obesogenic phenotypes across generations. The relationship between cholesterol accumulation in lysosomes that may lead to lysosome dysfunction and inhibition of the autophagy process is analyzed, as is the progression of inflammatory diseases, atherosclerosis, nonalcoholic liver inflammation, and obesity with associated complications. Data are discussed from analyses of differences between rodent models and human population studies in the investigated different effects of palm oil consumption as a high-fat diet component. A conclusion is reached that the results cannot be generalized in human population studies because no similar effects were observed. Although there are numerous published reports, more studies are necessary to elucidate the complex regulatory mechanisms in digestive and nutrition processes, because there are great differences in lipoprotein profiles between rodents and humans, which makes it difficult to reproduce the pathology of many diseases caused by different types of the high-fat diet.

Digestion and absorption of triacetin, a short-chain triacylglycerol

Triacylglycerol (TG) is categorized into long-, medium-, and short-chain TG (SCTG). While the digestion of long- and medium-chain TG is well established, the process for SCTG remains unclear. This study investigated SCTG digestion by administering 2 mmol of triacetin to rats and analyzing acetin, acetic acid, and glycerol levels in the portal blood and small intestine. Triacetin was fully degraded in the upper gastrointestinal tract and absorbed as acetic acid and glycerol. Glycerol influx into the liver promoted gluconeogenesis, while acetate activated AMPK, resulting in the suppression of fatty acid synthesis-related genes and the upregulation of fatty acid β-oxidation-related genes. These findings demonstrate that triacetin not only serves as a substrate for energy metabolism but also regulates hepatic gene expression, highlighting its dual role as both a metabolic substrate and signaling molecule. Triacetin thus shows potential as a dietary modulator for improving metabolic health.

Mechanical Properties and In Vitro Digestibility of Fermented Lentil and Quinoa Flour Food Prototypes for Older Adults

Background/Objectives: The increase in the older adult population worldwide and the need to switch to vegetal-origin protein consumption for environmental sustainability point to legumes and pseudocereals as alternative ingredients in new food formulations. This study aimed to assess the impact of food structure and fungal fermentation on the digestibility of new food prototypes made with quinoa and/or lentil flours addressed to older adults. Methods: Four gels and six breads were elaborated and subjected to mechanical analysis and simulated gastrointestinal in vitro digestion. Then, proteolysis, lipolysis, and amylolysis were analysed. Results: Gels made with fermented quinoa or lentil flours exhibited less hardness and required less force, suggesting better adequacy for mastication. In terms of digestibility, using fermented flours led to increased proteolysis and reduced starch hydrolysis. Conclusions: Our results support future studies in the field aimed at supplying older adults with adapted foods to satisfy their nutritional needs to prevent sarcopenia and other health issues.

The digestion fates of lipids with different unsaturated levels in people with different age groups

The digestion behavior of lipids plays a crucial role in their nutritional bioaccessibility, which subsequently impacts human health. This study aims to investigate potential variations in lipid digestion profiles among individuals of different ages, considering the distinct physiological functions of the gastrointestinal tract in infants, aging populations, and healthy young adults. The digestion fates of high oleic peanut oil (HOPO), sunflower oil (SO), and linseed oil (LINO) were investigated using in vitro digestion models representing infants, adults, and elders. Comparatively, lipid digestion proved to be more comprehensive in adults, leading to free fatty acid (FFA) levels of 64.53%, 62.32%, and 57.90% for HOPO, SO, and LINO, respectively. Besides, infants demonstrated propensity to selectively release FFAs with shorter chain lengths and higher saturation levels during the digestion. In addition, in the gastric phase, particle sizes among the elderly were consistently larger than those observed in infants and adults, despite adults generating approximately 15% FFAs within the stomach. In summary, this study enhances our fundamental comprehension of how lipids with varying degrees of unsaturation undergo digestion in diverse age groups.

Differences in Absorption and Metabolism between Structured 1,3-Oleate-2-palmitate Glycerol and 1-Oleate-2-palmitate-3-linoleate Glycerol on C57BL/6J Mice

This study investigated differences in absorption and metabolism between 1,3-oleate-2-palmitate glycerol (OPO) and 1-oleate-2-palmitate-3-linoleate glycerol (OPL) using C57BL/6J mice. OPL was associated with higher postprandial plasma total triacylglycerol (TG), low-density lipoprotein cholesterol (LDL-C) concentrations, and the ratio of LDL-C to high-density lipoprotein cholesterol (HDL-C) compared to those of OPO (p > 0.05). OPO significantly increased postprandial oleic acid (OA) concentrations compared to OPL over the entire monitoring period (p < 0.05), while OPL significantly elevated linoleic acid (LA) levels compared to OPO (p < 0.05). After 1 month of feeding, the mice in both OPO and OPL groups showed lower final weight, weight gain, and liver TG, LDL-C, and LDL/HDL concentrations compared to the control (soybean oil) group. Lipidomics results showed that OPO increased the biosynthesis of very long-chain fatty acids and decreased the abundance of AcCa (16:1), AcCa (18:2), AcCa (18:1), AcCa (16:0), CarE (16:0), and CarE (16:1) relative to OPL. These lipid metabolites were positively correlated with liver TG, LDL-C, and LDL/HDL levels and negatively related to peroxisome proliferator-activated receptors α (PPARα) and acyl-CoA oxidase (ACOX1) expression. This study showed differences in physiologic functions between OPO and OPL and provided support for the future application of OPL in infant formula.

Mechanisms of interesterified fat digestibility in a muffin matrix using a dynamic gastric model

Industrially generated trans-fats have been linked with cardiovascular disease (CVD) and have thus been replaced by interesterified (IE) fats, in foods. Interesterification rearranges fatty acids on the glycerol backbone of a triacylglycerol molecule. However, the impact of IE fat on health is unknown. We recently reported differences in lipid absorption kinetics between IE and rapeseed oil (RO). Here, we investigated the mechanisms underpinning IE fat digestion kinetics in the same muffins baked using an IE fat, non-IE fat [with the same fatty acid composition] and rapeseed oil (RO) under simulated conditions. IE and non-IE fats were largely solid in the gastric phase and strongly associated within the muffin matrix, whereas RO formed liquid droplets which separated from the matrix. No significant difference in lipolysis rates was detected between IE and non-IE fats. The lipolysis of the RO fat was slower, due to long-chain PUFAs. Interesterification itself did not affect digestibility, but the strong interaction between the hard fats and the muffin matrix resulted in extensive creaming of the matrix in the stomach, leading to delayed gastric emptying compared to the RO sample. The rate and extent of lipolysis were determined by the amount of fat available and the structure of the fat. This demonstrates the importance of the physical behaviour of the fats during digestion and provides a mechanistic understanding of the overall lipid digestion of IE fats, which relates to their physiological response.

Oleogelation of extra virgin olive oil by different gelators affects lipid digestion and polyphenol bioaccessibility

The possibility to steer extra virgin olive oil (EVOO) digestion and polyphenol bioaccessibility through oleogelation was investigated. EVOO was converted into oleogels using lipophilic (monoglycerides, rice wax, sunflower wax, phytosterols) or hydrophilic (whey protein aerogel particles, WP) gelators. In-vitro digestion demonstrated that the oleogelator nature influenced both lipid digestion and polyphenol bioaccessibility. WP-based oleogels presented ∼100% free fatty acid release compared to ∼64% for unstructured EVOO and ∼40 to ∼55% for lipophilic-based oleogels. This behavior was attributed to the ability of WP to promote micelle formation through oleogel destructuring. Contrarily, the lower lipolysis of EVOO gelled with lipophilic gelators compared to unstructured EVOO suggested that the gelator obstructed lipase accessibility. Tyrosol and hydroxytyrosol bioaccessibility increased for WP oleogels (∼27%), while liposoluble-based oleogels reduced it by 7 to 13%. These findings highlight the deep effect of the gelator choice on the digestion fate of EVOO components in the human body.

Effect of the oil from the fatty tissues of Crocodylus siamensis on gut microbiome diversity and metabolism in mice

Dietary fat can alter host metabolism and gut microbial composition. Crocodile oil (CO) was extracted from the fatty tissues of Crocodylus siamensis. CO, rich in monounsaturated- and polyunsaturated fatty acids, has been reported to reduce inflammation, counter toxification, and improve energy metabolism. The aim of this study was to investigate the effect of CO on gut microbiota (GM) in laboratory mice as well as the accompanying metabolic changes in the animals. Forty-five C57BL/6 male mice were randomly divided into five groups and orally administrated either sterile water (control [C]); 1 or 3% (v/w) CO (CO-low [CO-L] and CO-high [CO-H], respectively); or 1 or 3% (v/w) palm oil (PO-low and PO-high, respectively) for 11 weeks. Body weight gain, food intake, energy intake, blood glucose levels, and blood lipid profiles were determined. Samples from colon tissue were collected and the 16S rRNA genes were pyrosequenced to clarify GM analyses. The results showed that there were no differences in body weight and blood glucose levels. Food intake by the mice in the CO-L and CO-H groups was statistically significantly less when compared to that by the animals in the C group. However, neither CO treatment had a statistically significant effect on calorie intake when compared to the controls. The CO-H exhibited a significant increase in serum total cholesterol and low-density lipoprotein but showed a downward trend in triglyceride levels compared to the control. The GM analyses revealed that both CO treatments have no significant influence on bacterial diversity and relative abundance at the phylum level, whereas increases of Choa1 and abundance-based coverage estimator indexes, distinct β-diversity, and Proteobacteria abundance were observed in the PO-high group compared with the C group. Furthermore, the abundance of Azospirillum thiophilum and Romboutsia ilealis was significantly higher in the CO-L and CO-H groups which could be associated with energy metabolic activity. Thus, CO may be an alternative fat source for preserving host metabolism and gut flora.

Human milk phospholipid analog improved the digestion and absorption of 1,3-dioleoyl-2-palmitoyl-glycerol

The present study investigated the effects of a human milk phospholipid analog (HPLA) on the digestion and absorption of 1,3-dioleoyl-2-palmitoyl-glycerol (OPO). The HPLA contained 26.48% phosphatidylethanolamine (PE), 24.64% phosphatidylcholine (PC), 36.19% sphingomyelin (SM), 6.35% phosphatidylinositol (PI), and 6.32% phosphatidylserine (PS), with 40.51% C16:0, 17.02% C18:0, 29.19% C18:1, and 13.26% C18:2. The HPLA prevented OPO from hydrolysis during the in vitro gastric phase, while it facilitated the digestion of OPO during the in vitro intestinal stage, resulting in the production of large amounts of diglycerides (DAGs) and monoglycerides (MAGs). In vivo experimental results showed that the HPLA might increase the gastric emptying rate of OPO and increase the hydrolysis and absorption of OPO at an early stage of intestinal digestion. Notably, fatty acids in the serum of the OPO group decreased to their initial value at 5 h, while the serum of the OPO + HPLA (OPOH) group still contained a high level of fatty acids indicating that the HPLA was helpful in maintaining serum lipid at a high level, which might be beneficial for sustainably providing energy for babies. The present study provides data support for the potential application of Chinese human milk phospholipid analogs in infant formulas.

Analysis of Phospholipids in Digestion Using Hybrid IDA and SWATH Acquisition: An Example for Krill Oil

The composition and digestion of phospholipid-rich foods have important effects on the health of the body. Herein, a model-assisted liquid chromatography coupling mass spectrometry (LC-MS) method was established to analyze the phosphatidylcholine (PC) and lyso-phosphatidylcholine (LPC) species in krill oil before and after digestion. According to the confirmed PC and LPC species in the IDA (information dependent acquisition) results, three categories of mathematical models were set up, involving the retention time (RT), carbon number and unsaturation degree of the fatty acyl chain. All of the regression coefficient values (R²) were greater than 0.90, showing satisfactory fitting results. On this basis, using the computationally created precursor ion mass of PC and LPC species, 12 extra PC species and 4 LPC species were found in the SWATH (sequential windowed acquisition of all theoretical fragment ions) results. The PC and LPC compositions in the final digestive products had obvious differences among the different krill oils with different phospholipid content. Furthermore, more than half of the LPC species in the final digestive products were newly generated, indicating that LPC was one of basic constituents in the digestive products of krill oil. In conclusion, model-assisted hybrid IDA and SWATH acquisition has excellent detection performance, contributing to deep studies of the formations and functions of phospholipids.

New insights into the role of dietary triglyceride absorption in obesity and metabolic diseases

The incidence of obesity and associated metabolic diseases is increasing globally, adversely affecting human health. Dietary fats, especially triglycerides, are an important source of energy for the body, and the intestine absorbs lipids through a series of orderly and complex steps. A long-term high-fat diet leads to intestinal dysfunction, inducing obesity and metabolic disorders. Therefore, regulating dietary triglycerides absorption is a promising therapeutic strategy. In this review, we will discuss diverse aspects of the dietary triglycerides hydrolysis, fatty acid uptake, triglycerides resynthesis, chylomicron assembly, trafficking, and secretion processes in intestinal epithelial cells, as well as potential targets in this process that may influence dietary fat-induced obesity and metabolic diseases. We also mention the possible shortcomings and deficiencies in modulating dietary lipid absorption targets to provide a better understanding of their administrability as drugs in obesity and related metabolic disorders.

The gut microbiota-artery axis: A bridge between dietary lipids and atherosclerosis?

Atherosclerotic cardiovascular disease is one of the major leading global causes of death. Growing evidence has demonstrated that gut microbiota (GM) and its metabolites play a pivotal role in the onset and progression of atherosclerosis (AS), now known as GM-artery axis. There are interactions between dietary lipids and GM, which ultimately affect GM and its metabolites. Given these two aspects, the GM-artery axis may play a mediating role between dietary lipids and AS. Diets rich in saturated fatty acids (SFAs), omega-6 polyunsaturated fatty acids (n-6 PUFAs), industrial trans fatty acids (TFAs), and cholesterol can increase the levels of atherogenic microbes and metabolites, whereas monounsaturated fatty acids (MUFAs), ruminant TFAs, and phytosterols (PS) can increase the levels of antiatherogenic microbes and metabolites. Actually, dietary phosphatidylcholine (PC), sphingomyelin (SM), and omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been demonstrated to affect AS via the GM-artery axis. Therefore, that GM-artery axis acts as a communication bridge between dietary lipids and AS. Herein, we will describe the molecular mechanism of GM-artery axis in AS and discuss the complex interactions between dietary lipids and GM. In particular, we will highlight the evidence and potential mechanisms of dietary lipids affecting AS via GM-artery axis.

Effects of lipid type and toxicological properties on the digestion of cellulose nanocrystals in simulated gastrointestinal tract

This study aimed to understand the impact of different oil types on the cellulose nanocrystals (CNCs) to modulate lipid digestion and the in vitro gastrointestinal toxicity of CNCs in food systems. We explored the ability of CNCs to modulate lipid digestion in a simulated gastrointestinal system and monitored the gastrointestinal fate of CNC-based emulsions with different oil types. Finally, a small intestine epithelial model was used to evaluate the influence of cytotoxicity. The results suggested that the addition of 0.6 wt% CNCs in the high-fat food model reduced the hydrolysis of free fatty acids (FFAs) from triglycerides by 37.8% after the small intestine phase. CNCs showed the best effect in reducing lipid digestion in emulsions with high unsaturation triglycerides. In addition, the toxicology results suggest that 0.6 wt% CNCs had only a slight effect on reactive oxygen species and cytotoxicity, and no significant change in cell-layer integrity.

Crystal network structure and stability of beeswax-based oleogels with different polyunsaturated fatty acid oils

The effect of different types of oils including camellia oil (CLO), sunflower oil (SFO), corn oil (CO) and linseed oil (LO) on the formation, crystal network structure and mechanical properties of 4%wt beeswax (BW) in oleogel was investigated. BW oleogels containing oils with higher contents of polyunsaturated fatty acids gelled first (1%wt), especially LO with higher contents of linolenic acid rather than CLO with higher contents of monounsaturated fatty acids. In comparison, oils with higher polyunsaturated fatty acid contents exhibited higher D_b with more extensive microstructure at different cooling rates, which was related to shorter nucleation induction time of crystal and higher crystallinity. Stronger van der Waals forces were observed in oleogels with higher polyunsaturated fatty acid contents especially for LO oleogel. Rheology also showed that LO oleogel with higher content of linolenic acid had higher crystallinity and lower crystal melting interfacial tension, resulting in the formation of a more stable network structure.

Different typical dietary lipid consumption affects the bile acid metabolism and the gut microbiota structure: an animal trial using Sprague-Dawley rats

BACKGROUND

The palm oil (PO), leaf lard oil (LO), rapeseed oil (RO), sunflower oil (SO) and linseed oil (LN) are five of the most typical dietary lipids in most Asian countries. However, their influences on gut health, and the connections between the fatty acid composition, the gut microbiota, and the bile acid metabolism are not fully understood.

RESULTS

In the present study, results showed that compared with polyunsaturated fatty acid (PUFA)-rich SO and LN, the saturated fatty acid (SFA)-rich and monounsaturated fatty acid (MUFA)-rich PO, LO and RO were more likely to decrease the re-absorption of bile acid in the colon, which was probably caused by their different role in modulating the gut microbiota structure. LO consumption significantly up-regulated the Cyp27a1, FXR and TGR5 gene expression level (P < 0.05). The correlation results suggested that the C18:0 was significantly positive correlated with these three genes, indicating that intake of SFA-rich dietary lipids, especially for the C18:0, could specifically increase the bile acid production by stimulating the bile acid alternative synthesis pathway. Although the bile acid receptor expression in the colon was increased, the re-absorption of bile acid did not show a significant increase (P > 0.05) as compared with other dietary lipids. Moreover, the C18:2-rich SO maintained the bile acid metabolic balance probably by decreasing the Romboutsia, while increasing the Bifidobacterium abundance in the colon.

CONCLUSIONS

The different dietary lipids showed different effects on the bile acid metabolism, which was probably connected with the alterations in the gut microbiota structure. The present study could provide basic understandings about the influences of the different dietary lipids consumption on gut homeostasis and bile acid metabolism. © 2021 Society of Chemical Industry.

Interfacial characteristics and in vitro digestion of emulsion coated by single or mixed natural emulsifiers: lecithin and/or rice glutelin hydrolysates

BACKGROUND

The interfacial characteristics and in vitro digestion of emulsion were related to emulsifier type. The mean droplet diameter, ζ-potential, microstructure, interfacial tension, Quartz crystal microbalance with dissipation (QCM-D) and in vitro gastrointestinal fate of emulsions stabilized by soybean lecithin, hydrolyzed rice glutelin (HRG) and their mixture were researched.

RESULTS

The value of interfacial tension was much more dramatically declined for the sample containing 20 g kg^-1 of HRG. For QCM-D, a rigid layer was formed for all the samples after rinsing. The layer thickness was 0.87 ± 0.20, 2.11 ± 0.31 and 2.63 ± 0.22 nm, and adsorbed mass was 87.17 ± 10.31, 210.56 ± 20.12 and 263.09 ± 23.23 ng cm^-2 , for HRG, lecithin and HRG/lecithin, respectively, indicating both HRG and lecithin were adsorbed at the oil-water interface. Structural rearrangements at the interface occurred for HRG/lecithin. The kinetics and final amount of lipid digestion depended on emulsifier type: lecithin > HRG/lecithin > HRG. These differences in digestion rate were primarily due to differences in the aggregation state of the emulsifiers.

CONCLUSION

The incorporation of lecithin into HRG emulsions had better interfacial properties comparing with HRG emulsion and facilitated lipid digestibility. These results provide important information for the rational design of plant-based functional food. © 2021 Society of Chemical Industry.

Purified diet versus whole food diet and the inconsistent results in studies using animal models

In animal models, purified diets (PDs) and whole food diets (WFDs) are used for different purposes. In similar studies, different dietary patterns may lead to inconsistent results. The aim of this study was to evaluate and compare the effects of WFDs and PDs on changes in the metabolism of mice. We found that different dietary patterns produced different results in lipid metabolism experiments. Compared with those of the PD-fed mice, the WFD-fed mice had higher body weights and serum glucose, serum lipid, and liver lipid levels (p < 0.01), as well as low glucose tolerance (p < 0.01) and insulin sensitivity (p < 0.05). The body weight and fasting blood glucose increased by 20% in the WFD-fed mice, and the white adipose tissue weight increased by ∼50%. The WFD-fed mice also had a comparatively higher abundance of Lactobacillus, Turicibacter, Bifidobacterium, Desulfovibrio, and Candidatus saccharimonas (p < 0.01), which were positively correlated with lipid accumulation. Dietary patterns should be chosen cautiously in studies that use rodents as models. Inappropriate selection of animal dietary patterns may lead to experimental systematic errors and paradoxical results.

Different Effects of Lard and Vegetable Blend Oil on Intestinal Microorganisms, Enzyme Activity and Blood Routine in Mice

The intake of moderate oils and fats is necessary to maintain the body's energy balance, and the fatty acid composition of different oils and fats varies in their nutrition and function. The study aimed to investigate the effects of lard and vegetable blend oil on gut microbiota, intestinal enzyme activities, and blood routine. Kunming mice were assigned to the three groups: (1) Control group (CK) was gavage administration with distilled water, (2) Plant oil group (ZWY) was gavage administration with edible vegetable blend oil, (3) Lard group (DWY) was gavage administration with lard. After 42 days, microbiological, digestive enzymes, and blood routine were performed. Compared with the CK group, Escherichia coli, Lactobacilli, and Bifidobacteria were significantly decreased (p < 0.05), the activities of protease, cellulase, amylase, and xylanase were markedly reduced (p < 0.05), the hemoglobin was significantly increased (p < 0.05) in the ZWY group and DWY groups, and the hematocrit was increased in the ZWY group (p < 0.05), while other routine blood indices were increased (p > 0.05). Compared to the ZWY group, the activity of cellulase and amylase were significantly increased (p < 0.05), the intestinal microorganism and the routine blood indexes had no significant difference in the DWY group. Lard and vegetable blend oil diet affected the composition of the intestinal microorganisms, and the functions of digestive enzymes. Meanwhile, the levels of digestive enzymes may be correlated with the intestinal microbiota.

A Lard and Soybean Oil Mixture Alleviates Low-Fat-High-Carbohydrate Diet-Induced Nonalcoholic Fatty Liver Disease in Mice

Dietary habit is highly related to nonalcoholic fatty liver disease (NAFLD). Low-fat-high-carbohydrate (LFHC) diets could induce lean NAFLD in Asians. Previously, we found that a lard and soybean oil mixture reduced fat accumulation with a medium-fat diet; therefore, in this study, we evaluated the effect of a lard and soybean oil mixture (LFHC diet) on NAFLD and its underlying mechanisms. Mice in groups were fed with lard, soybean oil, or a lard and soybean oil mixture-an LFHC diet-separately. Our results showed that mixed oil significantly inhibited serum triglyceride, liver triglyceride, serum free fatty acids (FFAs), and liver FFAs compared with soybean oil or lard, and we found fewer inflammatory cells in mice fed with mixed oil. RNA-seq results indicate that mixed oil reduced FFAs transportation into the liver via decreasing liver fatty acid-binding protein 2 expression, inhibited oxidative phosphorylation via tumor necrosis factor receptor superfamily member 6 downregulation, and alleviated inflammation via downregulating inflammatory cytokine. The liquid chromatography-mass spectrometry results showed that the mixed oil promoted bile acid conjugated with taurine and glycine, thus activating G-protein-coupled bile acid receptor 1 for improved lipids metabolism. In conclusion, the lard and soybean oil mixture alleviated NAFLD.

Compositional, Structural, and Kinetic Aspects of Lipid Digestion and Bioavailability: In Vitro, In Vivo, and Modeling Approaches

Lipid digestion and bioavailability are usually investigated separately, using different approaches (in vitro, modeling, in vivo). However, a few inclusive studies show that their kinetics are closely linked. Lipid bioavailability kinetics is likely involved in the development and evolution of several diseases, so lipid digestion kinetics could be involved as well and can be modulated by food design or combination. To illustrate this possibility, the compositional and structural aspects of lipid digestion kinetics, as investigated using in vitro and modeling approaches, are presented first. Then, in vivo and mixed approaches enabling the study of both kinetics are reviewed and discussed. Finally, disparate modeling approaches are introduced, and a unifying modeling scheme is proposed, opening new perspectives for understanding the role and interactions of various factors (chemical, physical, and biological) involved in lipid metabolism.

Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Comprehensive lipidomics analysis of the lipids in hazelnut oil during storage

Although hazelnut oil is is nutritious, it is easily oxidized during storage. Thus far, changes in lipids during storage have not been comprehensively analyzed. Here, we used ultra-high liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) to dynamically monitor the lipid composition of hazelnut oil during accelerated storage for 24 d. A total of 10 subclasses of 103 lipids were identified. After 24 d, the content of triacylglycerol, diacylglycerol, phosphatidic acid, phosphatidylethanolamine, phosphatidylethanol, ceramide, and total lipids decreased significantly (P < 0.05). A total of 51 significantly different lipids were screened (Variable Importance in Projection > 1, P < 0.05), and these lipids could be used as biomarkers to distinguish fresh and oxidized hazelnut oil. We also detected seven most important pathways by bioinformatics analysis to explore the mechanism underlying changes. Our results provide useful information for future applications of hazelnut oil and provide new insight into edible oil oxidation.

Effects of Different Concentrations of Ganpu Tea on Fecal Microbiota and Short Chain Fatty Acids in Mice

Ganpu tea is composed of tangerine peel and Pu-erh tea. Current research suggests that both products can interact with gut microbes and thus affect health. However, as a kind of compound health food, little information is available about the effect of Ganpu tea on intestinal microorganisms. In this study, the basic physiological parameters (body weight, white adipose tissue and serum fat), the regulation of intestinal microorganisms and content of short-chain fatty acids (SCFAs) in feces of healthy mice were studied. The Ganpu tea can reduce the weight gain of mice and the increase in white adipose tissue (p < 0.01). After the intake of Ganpu tea, the abundance of Bacteroidetes increased (p < 0.05), whereas that of Firmicutes decreased (p < 0.01), indicating the latent capacity of Ganpu tea in adjusting the gut microbiota. Moreover, Ganpu tea differentially affected the content of different types of SCFAs in feces. Ganpu tea at the lowest concentrations showed positive effects on the concentrations of SCFAs such as acetic acid and propionic acid, whereas the concentration of butyric acid was decreased. For branched short-chain fatty acids (BSCFAs) such as isobutyric acid, isovaleric acid, etc., Ganpu tea reduced their concentrations. Our results indicated that Ganpu tea may have positive effects on preventing obesity in humans, but further research is needed before introducing such dietary therapy.

Metabolomics analysis of time-series human small intestine lumen samples collected in vivo

The human small intestine remains an elusive organ to study due to the difficulty of retrieving samples in a non-invasive manner. Stool samples as a surrogate do not reflect events in the upper gut intestinal tract. As proof of concept, this study investigates time-series samples collected from the upper gastrointestinal tract of a single healthy subject. Samples were retrieved using a small diameter tube that collected samples in the stomach and duodenum as the tube progressed to the jejunum, and then remained positioned in the jejunum during the final 8.5 hours of the testing period. Lipidomics and metabolomics liquid chromatography tandem mass spectrometry (LC-MS/MS) assays were employed to annotate 828 unique metabolites using accurate mass with retention time and/or tandem MS library matches. Annotated metabolites were clustered based on correlation to reveal sets of biologically related metabolites. Typical clusters included bile metabolites, food metabolites, protein breakdown products, and endogenous lipids. Acylcarnitines and phospholipids were clustered with known human bile components supporting their presence in human bile, in addition to novel human bile compounds 4-hydroxyhippuric acid, N-acetylglucosaminoasparagine and 3-methoxy-4-hydroxyphenylglycol sulfate. Food metabolites were observed passing through the small intestine after meals. Acetaminophen and its human phase II metabolism products appeared for hours after the initial drug treatment, due to excretion back into the gastrointestinal tract after initial absorption. This exploratory study revealed novel trends in timing and chemical composition of the human jejunum under standard living conditions.

Slow digestion-oriented dietary strategy to sustain the secretion of GLP-1 for improved glucose homeostasis

Dysregulated glucose metabolism is associated with many chronic diseases such as obesity and type 2 diabetes mellitus (T2DM), and strategies to restore and maintain glucose homeostasis are essential to health. The incretin hormone of glucagon-like peptide-1 (GLP-1) is known to play a critical role in regulating glucose homeostasis and dietary nutrients are the primary stimuli to the release of intestinal GLP-1. However, the GLP-1 producing enteroendocrine L-cells are mainly distributed in the distal region of the gastrointestinal tract where there are almost no nutrients to stimulate the secretion of GLP-1 under normal situations. Thus, a dietary strategy to sustain the release of GLP-1 was proposed, and the slow digestion property and dipeptidyl peptidase IV (DPP-IV) inhibitory activity of food components, approaches to reduce the rate of food digestion, and mechanisms to sustain the release of GLP-1 were reviewed. A slow digestion-oriented dietary approach through encapsulation of nutrients, incorporation of viscous dietary fibers, and enzyme inhibitors of phytochemicals in a designed whole food matrix will be implemented to efficiently reduce the digestion rate of food nutrients, potentiate their distal deposition and a sustained secretion of GLP-1, which will be beneficial to improved glucose homeostasis and health.

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.

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.

Different effects of high-fat diets rich in different oils on lipids metabolism, oxidative stress and gut microbiota

The study aimed to investigate the different effects of high-fat (HF) diets rich in different oils on lipid metabolism, oxidative stress, and gut mirobiota. C57BL/6 mice were divided into 4 groups: (1) control group (CG) was fed with normal diet, (2) olive oil (OO) group was fed with high-fat diet containing OO, (3) lard oil (LO) group was fed with high-fat diet containing LO, (4) soybean oil (SO) group was fed with high-fat diet containing SO. After 12 weeks, serum lipids, and oxidative stress indices were analyzed. Gut microbiota analysis was carried out based on the sequencing results of 16S rRNA. High fat diet can increase serum and liver lipids and upregulate sterol regulatory element-binding protein-1c related genes expression. Serum and liver malondialdehyde (MDA) levels in LO group were significantly higher than those in CG and OO groups. In CG, the family Muribaculaceae, Lactobacillaceae, Lachnospiraceae and Desulfovibrionaceae had the large effect sizes. HF diets resulted in the increase of Actinobacteria and Enterococcaceae abundance, and the decrease of Bacteroidetes, Proteobacteria Lactobacillales and microbiota diversity. The abundance of Actinobacteria and Lactobacillales is the link to the serum TC and MDA levels. HF diets have the harmful influence on the serum lipids, oxidative stress and endothelial function. They can also cause gut microbiota dysbiosis.

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.

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.

High level of dietary olive oil decreased growth, increased liver lipid deposition and induced inflammation by activating the p38 MAPK and JNK pathways in large yellow croaker (Larimichthys crocea)

A feeding experiment was conducted to determine the effects of fish oil replaced by olive oil (OO) on growth performance, serum biochemical, antioxidant capacity and inflammatory response in large yellow croaker (Larimichthys crocea). Four iso-nitrogenous and iso-lipidic diets were formulated by replacing fish oil (FO) with 0% (the control group), 33.3%, 66.7% and 100% OO. Fish fed the diet with 100% OO had the lowest growth performance among dietary treatments. However, there were no significant differences in SGR and FI among fish fed diets with 0% (the control group), 33.3% and 66.7% OO (P > 0.05). As to morphological parameters, HSI was significantly increased in fish fed the diet with 100% OO than the control group (P < 0.05). Furthermore, the lipid content of the liver in fish fed the diet with 100% OO was significantly higher than the control group (P < 0.05). Fish fed the diet with 100% OO had the highest content of C18:1n-9 among dietary treatments. Serum total triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C) levels and activity of serum alanine transaminase (ALT) were significantly increased in fish fed the diet with 100% OO compared with the control group (P < 0.05). Meanwhile, dietary OO decreased the activity of superoxide dismutase (SOD) and the total antioxidant capacity (T-AOC) in fish fed diets with increasing dietary OO levels. However, the content of malondialdehyde (MDA) was significantly increased in fish fed the diet with 100% OO compared with the control group (P < 0.05). The expression of pro-inflammatory genes, COX-2, IL-1β and TNFα, were significantly increased in the liver of fish fed the diet with 100% OO compared with the control group (P < 0.05), which was probably due to the activation of p38 mitogen-activated protein kinase (p38 MAPK) pathways and Jun N-terminal kinase (JNK) as the increased protein ratio of p-p38 MAPK to p38 MAPK and p-JNK to JNK. These results suggested that high level of dietary OO decreased the growth performance and antioxidant capacity but induced inflammation via the activation of p38 MAPK and JNK pathways in large yellow croaker.