Reciprocal responses to dietary diacylglycerol of hepatic enzymes of fatty acid synthesis and oxidation in the rat

Lipidomics profile of irradiated ground meat to support food safety

Meat irradiation is considered as an effective treatment that expose the advantageous effects on meat preservation. This research, based on untargeted LC-HR orbitrap MS-based lipidomics strategy was meant to estimate the alterations in lipid profile of irradiated chicken, turkey and mixed (chicken, turkey and pork) ground meat in order to evaluate if exists any food safety issue concerning the lipidome alteration. Special attention was paid on oxidation triggered by irradiation. All three matrices exhibited a characteristic lipidome profile which was affected differently by five levels of irradiation intensity. Overall, 345 lipids categorized into 14 subclasses were identified. Remarkably, the oxidized glycerophosphoethanolamines and oxidized glycerophosphoserines were identified in irradiated turkey meat, while for all three categories a characteristic diacylglycerols profile was recognised. Our analytical approach highlighted that the estimation of qualitative variations in lipid portion might be valuable in food inspection purposes, especially when the samples from animal origin are suspected on irradiation treatment.

An Oil Rich in γ-Linolenic Acid Differently Affects Hepatic Fatty Acid Oxidation in Mice and Rats

The effects of different dietary fats on hepatic fatty acid oxidation were compared in male ICR mice and Sprague-Dawley rats. Animals were fed diets containing 100 g/kg of either palm oil (saturated fat), safflower oil (rich in linoleic acid), an oil of evening primrose origin (γ-linolenic acid, GLA oil), perilla oil (α-linolenic acid) or fish oil (eicosapentaenoic and doxosahexaenoic acids) for 21 d. GLA, perilla and fish oils, compared with palm and safflower oils, increased the activity of fatty acid oxidation enzymes in both mice and rats, with some exceptions. In mice, GLA and fish oils greatly increased the peroxisomal palmitoyl-CoA oxidation rate, and the activity of acyl-CoA oxidase and enoyl-CoA hydratase to the same degree. The effects were much smaller with perilla oil. In rats, enhancing effects were more notable with fish oil than with GLA and perilla oils, excluding the activity of enoyl-CoA hydratase, and were comparable between GLA and perilla oils. In mice, strong enhancing effects of GLA oil, which were greater than with perilla oil and comparable to those of fish oil, were confirmed on mRNA levels of peroxisomal but not mitochondrial fatty acid oxidation enzymes. In rats, the effects of GLA and perilla oils on mRNA levels of peroxisomal and mitochondrial enzymes were indistinguishable, and lower than those observed with fish oil. Therefore, considerable diversity in the response to dietary polyunsaturated fats, especially the oil rich in γ-linolenic acid and fish oil, of hepatic fatty acid oxidation pathway exists between mice and rats.

The Science behind Microgreens as an Exciting New Food for the 21st Century

Chronic diseases are a major health problem in the United States. Accumulated data suggest that consumption of vegetables can significantly reduce the risk of many chronic diseases. Dietary guidelines for 2015-2020 from the U.S. Department of Agriculture and the U.S. Department of Health and Human Services recommend 1-4 cups of vegetables per day for males and 1-3 cups of vegetables per day for females, depending on their age. However, the average intake of vegetables is below the recommended levels. Microgreens are young vegetable greens. Although they are small, microgreens have delicate textures, distinctive flavors, and various nutrients. In general, microgreens contain greater amounts of nutrients and health-promoting micronutrients than their mature counterparts. Because microgreens are rich in nutrients, smaller amounts may provide similar nutritional effects compared to larger quantities of mature vegetables. However, literature on microgreens remains limited. In this Review, we discuss chemical compositions, growing conditions, and biological efficacies of microgreens. We seek to stimulate interest in further study of microgreens as a promising dietary component for potential use in diet-based disease prevention.

UPLC-Q-Exactive Orbitrap/MS-Based Lipidomics Approach To Characterize Lipid Extracts from Bee Pollen and Their in Vitro Anti-Inflammatory Properties

Bee pollen (BP) is collected by honeybees from flower pollen mixed with nectar and its secretions with extensive nutritional and therapeutic properties. Lipids are known to be critical contributors for the therapeutic effects of BP and vary depending on different plant sources; however, lipid profiles of BP are not available. Here, an UPLC-Q-Exactive Orbitrap/MS method was established for comprehensive lipidomics analysis of BP derived from three major nectar plants (Brassica campestris L., Camellia sinensis L., and Nelumbo nucifera Gaertn.). A total of nine lipid classes, including phosphatidylcholine (41 species), phosphatidylethanolamine (43 species), phosphatidylglycerol (9 species), phosphatidylserine (10 species), lysophosphatidylcholine (12 species), ceramide (8 species), diglyceride (27 species), triglyceride (137 species), and fatty acids (47 species), were first identified and quantified in the three BPs. In vitro anti-inflammatory activity was also discovered in the lipid extracts of three BPs, which has potential relevance to the abundance of phospholipids and unsaturated fatty acids in BP. Our comprehensive lipidomics profiling and in vitro anti-inflammatory properties of BP provide evidence for its future application.

Medium-Chain Enriched Diacylglycerol (MCE-DAG) Oil Decreases Body Fat Mass in Mice by Increasing Lipolysis and Thermogenesis in Adipose Tissue

Medium chain fatty acid (MCFA) escapes the formation of chylomicrons in the small intestine, resulting in energy expenditure through beta-oxidation. Diacylglycerol (DAG) is susceptible to oxidation rather than being stored in the adipose tissue. This study was conducted to verify the effect of MCE-DAG oil on body fat mass in vivo. Male C57BL/6 mice were randomly assigned to four groups (n = 12) as follows: (1) normal diet (18% kcal from fat), (2) canola oil as a control (40% kcal from canola oil), (3) MCE-DAG10 (10% kcal from MCE-DAG + 30% kcal from canola oil), and (4) MCE-DAG20 (20% kcal from MCE-DAG + 20% kcal from canola oil). The body weight and fat mass of MCE-DAG20 group mice were decreased relative to those of control mice (P < 0.05 and P < 0.001, respectively). Serum triacylglycerol (TAG) was decreased in both MCE-DAG10 and MCE-DAG20 groups (P < 0.01 and P < 0.05, respectively). Hormone sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) were increased in the MCE-DAG20 group relative to the control in white adipose tissue (WAT) (P < 0.05). Uncoupling protein 1 (UCP1) was also increased in the MCE-DAG20 group relative to the control in brown adipose tissue (BAT) (P < 0.05). In summary, MCE-DAG reduced body fat mass likely by stimulating lipolysis in WAT and thermogenesis in BAT.

Diacylglycerols from Palm Oil Deodoriser Distillate. Part 1 – Synthesis by Lipase-catalysed Esterification

Diacylglycerols (DAG) were synthesised by lipase-catalysed esterification of glycerol with fatty acids from palm oil deodoriser distillate (PODD). Effects of reaction parameters such as reaction time, temperature, enzyme type, enzyme load, substrate mole ratio and water content were determined. The effect of molecular sieves as a water adsorbent was also studied. Rhizomucor mieheilipase (Lipozyme RM IM) was found to be most effective among the lipases screened for DAG production. The following conditions yielded 52% (w/w) DAG: 6h reaction time, 65 °C reaction temperature, 10% (w/w) Lipozyme RM IM, 2.5:1 fatty acid to glycerol molar ratio, and 30% (w/w) molecular sieves. DAG synthesis of 10.9% (w/w) was still observed at 10% (w/w) water content.

Solvent-Free Lipase-Catalyzed Synthesis of Diacylgycerols as Low-Calorie Food Ingredients

Problems derived from obesity and overweight have recently promoted the development of fat substitutes and other low-calorie foods. On the one hand, fats with short- and medium-chain fatty acids are a source of quick energy, easily hydrolyzable and hardly stored as fat. Furthermore, 1,3-diacylglycerols are not hydrolyzed to 2-monoacylglycerols in the gastrointestinal tract, reducing the formation of chylomicron and lowers the serum level of triacylglycerols by decreasing its resynthesis in the enterocyte. In this work, these two effects were combined to synthesize short- and medium-chain 1,3-diacylglycerols, leading to a product with great potential as for their low-calorie properties. Lipase-catalyzed transesterification reactions were performed between short- and medium-chain fatty acid ethyl esters and glycerol. Different variables were investigated, such as the type of biocatalyst, the molar ratio FAEE:glycerol, the adsorption of glycerol on silica gel, or the addition of lecithin. Best reaction conditions were evaluated considering the percentage of 1,3-DAG produced and the reaction rate. Except Novozym 435 (Candida antarctica), other lipases required the adsorption of glycerol on silica gel to form acylglycerols. Lipases that gave the best results with adsorption were Novozym 435 and Lipozyme RM IM (Rhizomucor miehei) with 52 and 60.7% DAG at 32 h, respectively. Because of its specificity for sn-1 and sn-3 positions, lipases leading to a higher proportion of 1,3-DAG vs. 1,2-DAG were Lipozyme RM IM (39.8 and 20.9%, respectively) and Lipase PLG (Alcaligenes sp.) (35.9 and 19.3%, respectively). By adding 1% (w/w) of lecithin to the reaction with Novozym 435 and raw glycerol, the reaction rate was considerably increased from 41.7 to 52.8% DAG at 24 h.

Use of re-esterified palm oils, differing in their acylglycerol structure, in fattening pig diets

Re-esterified oils are new fat sources obtained from the chemical esterification of acid oils with glycerol (both economically interesting by-products from oil refining and biodiesel industries, respectively). The different fatty acid (FA) positional distribution and acylglycerol composition of re-esterified oils may enhance the apparent absorption of saturated fatty acids (SFA) and, therefore, their overall nutritive value, which might lead to an increased deposition of SFA. The aim of the present study was to investigate the potential use of re-esterified palm oils, in comparison with their corresponding acid and native oils in fattening pig diets, studying their effects on fatty acid apparent absorption, acylglycerol and free fatty acid (FFA) composition of feces, growth performance, carcass-fat depots and fatty acid composition of backfat. Seventy-two crossbred boars and gilts (average weight of 24.7 ± 2.55 kg) were blocked by initial BW (nine blocks of BW for each gender), housed in adjacent individual boxes, and fed one of the four dietary treatments, which were the result of a basal diet supplemented with 4% (as-fed basis) of native palm oil (PN), acid palm oil (PA), re-esterified palm oil low in mono- and diacylglycerols (PEL), or re-esterified palm oil high in mono- and diacylglycerols (PEH). Regarding results from the digestibility balance, PA and PN showed similar apparent absorption coefficients (P>0.05), despite the high, FFA content of the former. However, re-esterified palm oils (both PEL and PEH) showed a higher apparent absorption of total FA than did their corresponding native and acid oils (P0.05). We conclude that re-esterified oils are interesting fat sources to be considered in fattening pigs.

Re-esterified palm oils, compared to native palm oil, do not alter fat absorption, postprandial lipemia or growth performance in broiler chicks

Re-esterified palm oils are obtained from the chemical esterification of palm acid oils (rich in free fatty acids) with glycerol, both economically interesting by-products from oil refining and biodiesel industries, respectively. Thus, re-esterified palm oils could be an economically interesting alternative to native palm oil in broiler chick diets. However, because they may have different physicochemical properties than have their corresponding native oil, we assessed the effect of fatty acid (FA) positional distribution within acylglycerol molecules and the effect of acylglycerol composition on FA apparent absorption, and their possible consequences on the evolution of postprandial lipemia and growth performance in broiler chicks. Seventy-two 1-day-old female broiler chicks were randomly distributed into 18 cages. The three treatments used were the result of a basal diet supplemented with 6 wt% of native palm oil (N-TAG), re-esterified palm oil (E-TAG), or re-esterified palm oil high in mono- and diacylglycerols (E-MDAG). Chemical esterification raised the fraction of palmitic acid at the sn-2 position from 9.63 mol% in N-TAG oil to 17.9 mol% in E-TAG oil. Furthermore, E-MDAG oil presented a high proportion of mono- (23.1 wt%) and diacylglycerols (51.2 wt%), with FA mainly located at the sn-1,3 positions, which resulted in a lower gross-energy content and an increased solid-fat index at the chicken’s body temperature. However, re-esterified palm oils did not alter fat absorption, postprandial lipemia, or growth performance, compared to native palm oil, so they can be used as alternative fat sources in broiler chick diets.

Involvement of SIRT1-AMPK signaling in the protective action of indole-3-carbinol against hepatic steatosis in mice fed a high-fat diet

This study addressed the effect of indole-3-carbinol (I3C) supplementation on hepatic steatosis in mice fed a high-fat diet (HFD) and clarified the underlying mechanism. Male C57BL/6N mice were divided into three groups: those who received a normal diet, those fed with HFD and those fed with 0.1% I3C-supplemented diet (I3CD). In the present study, an HFD supplemented with 0.1% I3C significantly decreased body and liver weight as well as plasma and hepatic lipid levels. The activation of the silent mating type information regulation 2 homolog 1 (SIRT1)-AMP-activated protein kinase (AMPK) signaling system by I3C correlated with decreased mRNA levels of sterol regulatory element-binding protein-1c-regulated lipogenic enzymes. In addition, I3C significantly reversed HFD-induced up-regulation of ER stress-mediated signaling molecules in the liver, which may have contributed to the protective effects of I3C against hepatic steatosis. Furthermore, HFD-induced up-regulations of inflammatory genes such as tumor necrosis factor α and interleukin 6 were significantly reversed by dietary I3C supplementation. Our study suggests that the protective action of I3C against hepatic steatosis is mediated, at least in part, through the up-regulation of a SIRT1-AMPK signaling system in the livers of HFD-fed mice. Further investigations revealed that alleviation of the ER stress response represented a critical mechanism underlying the beneficial effects of I3C on hepatic steatosis.

Substitution of TAG oil with diacylglycerol oil in food items improves the predicted 10 years cardiovascular risk score in healthy, overweight subjects

Dietary fat is normally in TAG form, but diacylglycerol (DAG) is a natural component of edible oils. Studies have shown that consumption of DAG results in metabolic characteristics that are distinct from those of TAG, which may be beneficial in preventing and managing obesity. The objective of the present study was to investigate if food items in which part of the TAG oil is replaced with DAG oil combined with high α-linolenic acid (ALA) content would influence metabolic markers. A 12-week double-blinded randomised controlled parallel-design study was conducted. The participants (n 23) were healthy, overweight men and women, aged 37–67 years, BMI 27–35 kg/m², with waist circumference >94 cm (men) and >88 cm (women). The two groups received 20 g margarine, 11 g mayonnaise and 12 g oil per d, containing either high ALA and sn-1,3-DAG or high ALA and TAG. Substitution of TAG oil with DAG oil in food items for 12 weeks led to an improvement of the predicted 10 years cardiovascular risk score in overweight subjects by non-significantly improving markers of health such as total body fat percentage, trunk fat mass, alanine aminotransferase, systolic blood pressure, γ-glutamyl transferase, alkaline phosphatase and total fat-free mass. This may suggest that replacing TAG oil with DAG oil in healthy, overweight individuals may have beneficial metabolic effects.

Diacylglycerol: Efficacy and Mechanism of Action of an Anti-Obesity Agent

Obesity is at the forefront of global health issues and directly contributes to many chronic illnesses. Several dietary components show promise in the treatment of obesity, one of which is oil rich in diacylglycerols (DAGs). Present objectives are to examine scientific knowledge concerning DAG to assess evidence supporting the effects on substrate oxidation rates, body weight and fat mass, and blood lipids, and to assess safety, as well as elucidate potential mechanisms of action. DAG can be synthesized by an enzymatic process to produce mainly 1,3-isoform DAG. This 1,3-DAG oil is believed to have the ability to increase beta-oxidation, to enhance body weight loss, to suppress body fat accumulation, and to lower serum triacylglycerol levels postprandially. While certain animal and human studies indicate that consumption of 1,3-DAG has positive physiological effects, others report no effect. The mechanisms of action of DAG are suggested to decrease the resynthesis of chylomicrons as well as shunting them directly to the liver through the portal vein, where they are oxidized. This increased fat oxidation may influence control of food intake by increasing satiety. Further study into the precise mechanism is required to understand its effects. Safety studies show no risks in consuming a diet rich in DAG oil. Overall, consumption of oils with higher amounts of DAG, specifically 1,3-DAG, may be useful in the battle against obesity.

Effects of a meal rich in 1,3-diacylglycerol on postprandial cardiovascular risk factors and the glucose-dependent insulinotropic polypeptide in subjects with high fasting triacylglycerol concentrations

It was previously reported that compared to triacylglycerol (TAG) oil, diacylglycerol (DAG) oil improves postprandial lipid response. However, the effects of DAG oil on postprandial hyperglycemia and incretin response have not yet been determined. In this study, the effects of DAG oil on both postprandial hyperlipidemia and hyperglycemia and the response to the glucose-dependent insulinotropic polypeptide (GIP) were studied. This randomized, double-blind, crossover study analyzed data for 41 individuals with high fasting triacylglycerol concentrations. The subjects ingested test meals (30.3 g of protein, 18.6 g of fat, and 50.1 g of carbohydrate) containing 10 g of DAG oil (DAG meal) or TAG oil (TAG meal) after fasting for at least 12 h. Blood samples were collected prior to and 0.5, 2, 3, 4, and 6 h after ingestion of the test meal. Postprandial TAG concentrations were significantly lower after the DAG meal compared with the TAG meal. Postprandial TAG, insulin, and GIP concentrations were significantly lower after the DAG meal compared with the TAG meal in 26 subjects with fasting serum TAG levels between 1.36 and 2.83 mmol/L. DAG-oil-based meals, as a replacement for TAG oil, may provide cardiovascular benefits in high-risk individuals by limiting lipid and insulin excursions.

Dietary effects of diacylglycerol rich mustard oil on lipid profile of normocholesterolemic and hypercholesterolemic rats

Several recent studies have established that diacylglycerol (DAG) rich oils significantly reduce the body weight. The present study was conducted to evaluate the dietary effects of DAG- rich mustard oil on normal and hypercholesterolemic rats. DAG- rich mustard oil (45.5% DAG) was prepared in the laboratory by enzymatic glycerolysis process. For the feeding experiment, 32 rats were taken and divided into four groups (average body weight 130 g) and body weight gain, food efficiency ratio, lipid profile of plasma, liver, mesentery and erythrocytes membrane (EM), HMG Co-A reductase activity and plasma leptin content were measured and compared with the normal TAG-rich diet. The dietary DAG rich mustard oil significantly decreased body weight and FER compared to TAG rich mustard oil both in normal and hypercholesterolemic rats. The total cholesterol content was decreased with significant increase in HDL- cholesterol by feeding DAG rich diet. Total lipid and TAG content of both liver and mesentery were significantly decreased in DAG diet group compared to control group. Liver HMG CoA: mevalonate ratio was also found to be significantly decreased in the DAG group. Blood leptin level significantly reduced with DAG rich diet compared to the TAG rich dietary groups.

Postprandial lipid-related metabolites are altered in dogs fed dietary diacylglycerol and low glycemic index starch during weight loss

In this study, we investigated a combination of a low glycemic index starch (LGIS) and diacylglycerol (DAG) on lipid, lipoprotein (LP) metabolism, and weight management. Obese, intact female adult Beagle dogs were assigned to 1 of 4 starch/oil combination diets [LGIS/DAG (LD); LGIS/triacylglycerol (TAG); high glycemic index starch (HGIS)/DAG; and HGIS/TAG (HT)] and fed for 9 wk (n = 6/group) using an incomplete 4 × 4 Latin square design. Each dog was fed 1 of 2 opposite starch/oil combination diets (e.g. LD and HT). At wk 1 and 8, postprandial blood was collected for plasma triacylglycerol (TG), β-hydroxybutyrate (BHB), total cholesterol (TC), and LP analyses. During the same week, dogs were overnight feed-deprived and post-heparin blood was collected for LP lipase and hepatic lipase activity determinations. At wk 1, 4, and 8, blood was drawn from overnight feed-deprived dogs for plasma TG, BHB, TC, LP, leptin, and adiponectin measurements. Feces were collected at wk 3 for digestibility calculations. The LGIS diets resulted in lower carbohydrate, protein, total tract dry matter digestibilities, and metabolizable energy compared with the HGIS diet groups (P < 0.05). Thus, the LGIS groups lost more body weight (P = 0.001), which was positively correlated with plasma leptin concentrations (r(2) = 0.427; P < 0.001). Moreover, the LGIS diet lowered TC concentrations in combination with DAG. The DAG diet groups decreased postprandial TG and increased BHB concentrations (P < 0.05). Starch/oil types did not alter lipase activities or adiponectin concentrations. In conclusion, the LGIS diet demonstrated potential as a weight management tool in dogs by decreasing postprandial TG and increasing BHB in combination with DAG.

Structured triacylglycerol containing behenic and oleic acids suppresses triacylglycerol absorption and prevents obesity in rats

Background

Dietary 1(3)-behenoyl-2,3(1)-dioleoyl-rac-glycerol (BOO) has been reported to inhibit pancreatic lipase activity in vitro and suppress postprandial hypertriacylglycerolemia in humans. In the present study, the anti-obesity activities of BOO and its inhibitory effects on lymphatic triacylglycerol (TAG) absorption were investigated in rats.

Methods

In Experiment 1, rats were fed either BOO or soybean oil (SO) diet for 6 weeks. In the BOO diet, 20% of SO was replaced with an experimental oil rich in BOO. In Experiments 2 and 3, rats cannulated in the thoracic duct were administered an emulsions containing trioleoylglycerol (OOO) or an oil mixture (OOO:BOO, 9:1). Tri[1-¹⁴C]oleoylglycerol (¹⁴C-OOO) was added to the emulsions administered in Experiment 3.

Results

No observable differences were detected in food intake or body weight gain between the BOO and SO groups in Experiment 1. Plasma and liver TAG concentrations and visceral fat weights were significantly lower in the BOO group than in the SO group. The apparent absorption rate of fat was significantly lower in the BOO group than in the SO group. In Experiment 2, the lymphatic recovery of oleic and behenic acids was significantly lower at 5 and 6 h after BOO administration than after OOO administration. In Experiment 3, the lymphatic recovery of ¹⁴C-OOO was significantly lower at 5 and 6 h after BOO administration than after OOO administration.

Conclusions

These results suggest that BOO prevents deposition of visceral fat and hepatic TAG by lowering and delaying intestinal absorption of TAG.

Diacylglycerol oil reduces body fat but does not alter energy or lipid metabolism in overweight, hypertriglyceridemic women

Diacylglycerol (DAG) may undergo differential metabolism compared with triacylglycerol (TAG) in humans, possibly resulting in decreased serum TAG concentration and TAG synthesis and increased energy expenditure (EE), thus reducing fat accumulation. Our objective was to examine the efficacy of DAG oil (Enova oil) consumption on serum lipid profiles, hepatic lipogenesis, EE, and body weight and composition compared with a control oil-blend composed of sunflower, safflower, and rapeseed oils at a 1:1:1 ratio. Twenty-six overweight (78.3 +/- 3.6 kg body weight and BMI 30.0 +/- 0.7 kg/m(2)) mildly hypertriglyceridemic (1.81 +/- 0.66 mmol/L) women underwent 2 treatment phases of 28 d separated by a 4-wk washout period using a randomized crossover design. They consumed 40 g/d of either DAG or control oil during treatment phases. The baseline, EE, fat oxidation, body composition, and lipid profiles did not differ between the DAG and control oil intervention periods. Relative to control oil, DAG oil did not alter endpoint postprandial EE, fat oxidation, serum lipid profiles, or hepatic lipogenesis. However, DAG oil consumption reduced (P < 0.05) accumulation of body fat within trunk, android, and gynoid regions at the endpoint compared with control oil, although neither DAG nor control oil altered any of these variables during the 4-wk intervention period compared with their respective baseline levels. We conclude that although DAG oil is not effective in lowing serum lipids over a 4-wk intervention, it may be useful for reducing adiposity.

Effects of simultaneous intake of soybean protein and diacylglycerol on lipid profiles and body fat accumulation in rats

Soybean protein (SPI) and diacylglycerol (DAG) are functional components with benefits for lipid metabolism. Since simultaneous intake of such components is expected to exert effects additively and/or synergistically in lifestyle-related diseases, we examined the effects of simultaneous intake of SPI and DAG on lipid profiles. Five-week-old male Wistar rats were fed experimental diets with and without cholesterol for 28 d. In the rats fed cholesterol-free diets, significant interactions between dietary oil and protein were observed in the serum triacylglycerol (TG), hepatic cholesterol, and TG concentrations, whereas in the rats fed cholesterol diets, the serum and hepatic lipid concentrations were significantly lower in rats fed SPI than in those fed casein. Although our results suggest that simultaneous intake of SPI and DAG has slightly ameliorating effects on lipid profiles in rats, simultaneous intake of foods or foods components with similar functions are not necessarily effective.

Genes are differentially expressed in the epididymal fat of rats rendered obese by a high-fat diet

The aim of present study was to identify the visceral adipose tissue genes differentially expressed in a well-characterized rat model of high-fat diet (HFD)-induced obesity. Male Sprague-Dawley rats were fed either the HFD (17 g lard + 3 g corn oil/100 g) or the normal diet (5 g corn oil/100 g) for 9 weeks. The HFD rats weighed 55% more and accumulated 85% to 133% greater visceral fats than did the normal-diet rats (P < .05). Animals given the HFD for 9 weeks acquired dyslipidemia, fatty liver, insulin resistance, and hyperleptinemia along with the overexpression of several obesity-related genes, such as leptin, tumor necrosis factor alpha, resistin, peroxisome proliferator-activated receptor gamma2, CCAAT/enhancer-binding protein alpha, and sterol regulatory element-binding protein-1c, in the epididymal adipose tissue. The differential gene expression profile obtained from the cDNA microarray analysis followed by the real-time polymerase chain reaction confirmation led to a recruitment of several uncharacterized adipose tissue genes responding to the HFD. We report herein, for the first time, that a series of genes which might be implicated in the insulin-stimulated glucose transporter 4 translocation, such as protein phosphatase 2 (formerly 2A), cell division cycle 42-interacting protein 4, syntaxin 6, linker of T-cell receptor pathways 10, as well as the genes which might be involved in cancer development, such as heat shock 10-kd protein 1, and ras-related C3 botulinum toxin substrate 1, were differentially expressed in the epididymal adipose tissue of rats rendered obese by an HFD.

The effects of diacylglycerol oil on fat oxidation and energy expenditure in humans and animals

Studies in animals and humans indicate that diets containing diacylglycerol (DAG) oil (containing >80% DAG) decrease body weight gain and body fat accumulation, especially visceral fat. Body weight and body fat are controlled by energy expenditure, fat oxidation, fat storage capacity, and appetite control. Recent researches indicate that DAG oil, compared with conventional oils, has distinct metabolic effects. We review the evidence concerning the effects of DAG oil intake on fat oxidation and energy expenditure. In humans, dietary DAG is more susceptible to oxidation, and in animals 1,3-DAG, a major component of DAG oil, is rapidly oxidized. Short-term human studies with indirect calorimetry demonstrate greater fat oxidation with DAG oil consumption compared with triacylglycerol (TAG) oil consumption. Furthermore, DAG oil consumption for 14 days stimulates energy expenditure. Based on these reports, enhanced fat oxidation and energy expenditure by daily DAG oil intake could contribute to long-term reductions in body weight and fat accumulation. The literature provides support for the notion that dietary DAG is more rapidly oxidized than dietary TAG, and that, compared with TAG oil, DAG oil consumption increases whole body fat oxidation. The effects of DAG oil consumption on energy expenditure, however, remain inconclusive. (c) 2009 International Union of Biochemistry and Molecular Biology, Inc.

Dietary docosahexaenoic acid-rich diacylglycerols ameliorate hepatic steatosis and alter hepatic gene expressions in C57BL/6J-Lep(ob/ob) mice

We examined the effect of docosahexaenoic acid (DHA)-enriched structured lipids-diacylglycerol (SL-DG), which were synthesized using soybean oil (SO) and algae oil (AO), on hepatic lipid metabolism and the mRNA expression of genes involved in hepatic steatosis of C57BL/6J-Lep(ob/ob) compared to the SL-triacylglycerol (TG). The animals were fed a high-fat (10% lard and 10% test oils) and high-cholesterol (0.2% cholesterol) diet for 12 weeks. Mice fed SL-DG showed a lower total white adipose tissue weight and plasma triglyceride concentration than the SO group. Reduction of hepatic triglyceride content in the SL-DG group was related with the suppression of hepatic enzyme activities for fatty acid and triglyceride synthesis along with fecal triglyceride excretion compared to the SL-TG. SL-DG also lowered hepatic cholesterol levels by suppressing cholesterol regulating enzyme activity compared to the SO group. Moreover, SL-DG lowered the mRNA expressions of sterol regulatory element binding protein-1 and its target genes than TG-form oils (SO, AO and SL-TG) in the liver. Thus, the current results suggest that DHA-enriched SL-DG oil used in this study is beneficial for ameliorating hepatic steatosis in obese animal model by improving hepatic fatty acid and cholesterol metabolic enzyme activity and their gene expression.

Greater fat oxidation with diacylglycerol oil consumption for 14 days compared with triacylglycerol oil consumption in overweight men and women

BACKGROUND

Several studies have reported increased fat oxidation with diacylglycerol (DAG) oil consumption. However, the effects of long-term DAG oil consumption on energy metabolism remain to be investigated.

OBJECTIVE

The objective of this study was to compare the effects of 14 days of either DAG or triacylglycerol (TAG) oil consumption on substrate oxidation, energy expenditure (EE) and dietary fat oxidation.

DESIGN

Eight males and six females participated in this randomized, double-blind, crossover feeding study. Each patient consumed the 14-day controlled test diet containing either 10 g day(-1) of DAG or TAG oil for acclimatization before a respiratory chamber measurement, followed by a 2-week washout period between diet treatments. Substrate oxidation and EE were measured in the respiratory chamber at the end of each dietary treatment. The patients consumed test oil as 15% of total caloric intake in the respiratory chamber (mean test oil intake was 36.1+/-6.6 g day(-1)).

RESULTS

Twenty-four hour fat oxidation was significantly greater with 14 days of DAG oil consumption compared with TAG oil consumption (78.6+/-19.6 and 72.6+/-14.9 g day(-1), respectively, P<0.05). There were no differences in body weight or body composition between diet treatments. Dietary fat oxidation was determined using the recovery rate of (13)CO(2) in breath, and was significantly enhanced with DAG oil consumption compared with TAG oil consumption, measured over 22 h after ingestion of (13)C-labelled triolein. Resting metabolic rate (RMR) was significantly greater with DAG oil consumption compared with TAG oil consumption (1766+/-337 and 1680+/-316 kcal day(-1), respectively, P<0.05).

CONCLUSION

Consumption of DAG oil for 14 days stimulates both fat oxidation and RMR compared with TAG oil consumption, which may explain the greater loss of body weight and body fat with DAG oil consumption that has been observed in weight-loss studies.

Lipase catalyzed synthesis of neutral glycerides rich in micronutrients from rice bran oil fatty acid distillate

Neutral glycerides with micronutrients like sterols, tocopherols and squalene may be prepared from cheap raw material like rice bran oil fatty acid distillate (RBO FAD). RBO FAD is an important byproduct of vegetable oil refining industries in the physical refining process. Glycerides like triacylglycerols (TAG), diacylglycerols (DAG) and monoacylglycerols (MAG) containing significant amounts of unsaponifiable matter like sterols, tocopherols and hydrocarbons (mainly squalene) may certainly be considered as novel functional food ingredients. Fatty acids present in RBO FAD were esterified with glycerol of varying amount (1:0.33, 1:0.5, 1:1 and 1:1.5 of FAD : glycerol ratio) for 8 h using non-specific enzyme NS 40013 (Candida antartica). After esterification the product mixture containing mono, di- and triglycerides was purified by molecular distillation to remove excess free fatty acids and also other volatile undesirable components. The purified product containing sterols, tocopherols and squalene can be utilized in various food formulations.

Diacylglycerol-induced improvement of whole-body insulin sensitivity in type 2 diabetes mellitus: a long-term randomized, double-blind controlled study

BACKGROUND & AIMS

Diacylglycerol oil has been shown to lower postprandial and fasting serum triacylglycerol levels and reduce body fat. The aim of this study was to investigate the effect of diacylglycerol oil on risk factors of type 2 diabetes mellitus (DM) and cardiovascular disease in type 2 DM patients.

METHODS

This was a double-blind controlled parallel study with 127 type 2 DM patients (aged 40-65) recruited in Hangzhou, China. All subjects consumed triacylglycerol oil in the lead-in period (14 days), then they were randomly divided into two groups and consumed diacylglycerol or triacylglycerol oil with a similar fatty acid composition (25 g/day) for 120 days. Blood samples were collected on days 0, 60 and 120 and risk factors of type 2 DM and cardiovascular disease and biochemical parameters were measured by standard methods.

RESULTS

There were a total of 112 subjects who completed the study. Diet intake did not differ significantly between groups. Body weight, BMI, waist circumference, HOMA-IR, serum insulin and leptin levels were significantly reduced from baseline in the diacylglycerol oil group but not in the triacylglycerol oil group. Serum glucose was also significantly improved in patients with higher glucose levels at baseline (>7.00 mmol/L) in the diacylglycerol oil group. Parameters of liver and kidney functions and essential fatty acids in serum phospholipids did not differ between groups.

CONCLUSIONS

Diacylglycerol oil consumption improved biomarkers and anthropometric parameters of type 2 DM compared with triacylglycerol oil. No adverse reactions were observed with diacylglycerol oil consumption for type 2 DM patients. Diacylglycerol oil has an equivalent bioavailability as triacylglycerol oil in relation to providing essential fatty acids.

Effects of a 1,3-diacylglycerol oil-enriched diet on postprandial lipemia in people with insulin resistance

Postprandial hypertriglyceridemia is common in individuals with insulin resistance, and diets enriched in 1,3-diacylglycerol (DAG) may reduce postprandial plasma triglycerides (PPTGs). We enrolled 25 insulin-resistant, nondiabetic individuals in a double-blind, randomized crossover trial to test the acute and chronic effects of a DAG-enriched diet on PPTG. Participants received either DAG or triacylglycerol (TAG) oil, in food products, for 5 weeks. Fasting lipids, and two separate postprandial tests, one with DAG oil and one with TAG oil, were performed at the end of each 5 week diet period. We found no acute or chronic effects of DAG oil on PPTG. Thus, neither the DAG oil PPTG (h/mg/dl) on a chronic TAG diet [area under the curve (AUC) = 503 +/- 439] nor the TAG oil PPTG on a chronic DAG diet (AUC = 517 +/- 638) was different from the TAG oil PPTG on a chronic TAG diet (AUC = 565 +/- 362). Five weeks of a DAG-enriched diet had no acute or chronic effects on PPTG in insulin-resistant individuals. We suggest further studies to evaluate the effects of DAG on individuals with low and high TG levels.

Suppressive effects of diacylglycerol oil on postprandial hyperlipidemia in insulin resistance and glucose intolerance

The diacylglycerol (DAG), a commonly used as a cooking oil in Japan, results in a lower elevation of serum triglyceride (TG) after ingestion compared to triacylglycerol (TAG). Postprandial hyperlipidemia (PPHL) and an increase in remnant lipoproteins (RLP) levels are risk factors for CAD, and a close relationship between PPHL and type 2 diabetes and/or insulin resistance has been reported. To evaluate the effect of DAG on PPHL in insulin resistance and glucose intolerance, 11 subjects with a normal glucose tolerance (NGT) and 14 subjects with IGT received oral fat tolerance test (OFTT) twice. They ingested emulsified test oils prepared with either DAG or TAG. In the IGT subjects, after the DAG and TAG load, the serum concentrations of TG, RLP-TG, and RLP-cholesterol increased throughout the 4-h study. The responses of these variables above baseline after the DAG load were significantly smaller than those after the TAG load (p<0.05). In contrast, in the NGT subjects, changes in these parameters were much smaller than those observed for IGT subjects. The difference in the integrated responses for serum RLP-cholesterol concentration during OFTT between DAG and TAG in all subjects can be easily explained by the integrated response of insulin rather than glucose during oral glucose tolerance test (r=0.7, p<0.01). DAG was more effective in insulin resistant and hyperinsulinemic participants regardless of glucose intolerance, and may be beneficial in reducing the extent of CAD risk in such individuals.

Dietary 1,3-diacylglycerol protects against diet-induced obesity and insulin resistance

To investigate the effect of dietary 1,3-diacylglycerol (DAG) on the development of insulin resistance (IR) and obesity, brown adipose tissue-deficient mice, a model of high-fat diet-induced IR and obesity, were fed Western-type diets (WTD) containing either DAG oil (n = 8) or standard triacylglycerol (TAG) oil (n = 9) for 15 weeks, beginning at 8 weeks of age. Although brown adipose tissue-deficient mice became obese on both TAG- and DAG-enriched WTD (TAG-WTD and DAG-WTD), the mice eating DAG-WTD gained less weight and had less body fat accumulation. The results of glucose tolerance tests conducted after 5 weeks of each WTD were not different. However, after 10 weeks of each WTD, impaired glucose tolerance developed in the TAG-WTD group but was prevented by DAG-WTD. Exploratory analyses of gene expression suggested that consumption of DAG-WTD was associated with reduced phosphoenolpyruvate carboxykinase gene expression in liver and increased expression of the genes for peroxisome proliferator-activated receptor alpha, lipoprotein lipase, and uncoupling proteins 2 and 3 in skeletal muscle. There were no effects of the DAG-WTD on fasting and postprandial plasma triglyceride (TG) levels, hepatic TG content, or the rate of secretion of TG from the liver. These findings suggest that diets enriched in 1,3-DAG oil may reduce WTD-induced IR and body fat accumulation by suppressing gluconeogenesis in liver and stimulating fat oxidation in skeletal muscle.

Hypolipidemic effect of dietary diacylglycerol oil in Sprague-Dawley rats fed a normal diet

The present study compared the effects of dietary diacylglycerol (DG) and triacylglycerol (TG) oil on lipid metabolism in rats fed a 5% fat (AIN-76) diet for 6 weeks. The plasma and hepatic lipids, hepatic cholesterol-regulating enzyme activity, and hepatic and adipose tissue fatty acid metabolism enzyme activities were determined. Among plasma lipids, triglyceride, free fatty acid, and phospholipid concentrations were significantly lower in the DG group than in the TG group. A lower plasma TG level was accompanied by an increase in adipocyte lipoprotein lipase activity. The hepatic triglyceride level was significantly (P < .001) lowered in the DG group, which was attributable to an increased fatty acid oxidation enzyme (beta-oxidation) activity and a reduced fatty acid synthesis enzyme (glucose-6-phosphate dehydrogenase) activity. The plasma cholesterol concentration was significantly lower in the DG group and was accompanied by a lower hepatic 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity. The DG oil used in this study was beneficial for enhancing lipid metabolism with apparent hypolipidemic effects.

Respective hydrolysis and esterification of esterified and free plant stanols occur rapidly in human intestine after their duodenal infusion in triacyl- or diacylglycerol

Esterification of dietary phytosterols and glycerols may affect intestinal absorption of cholesterol and non-cholesterol sterols. We infused plant stanol esters in triacylglycerol (TAG) (F1) and diacylglycerol (DG) (F2) oils, and free plant stanols in F1 and F2 (F3) to the duodenum of healthy human subjects and sampled the contents from the proximal jejunum (PJ). Free and ester sterols were analysed from the infusates, and intestinal contents before and after ultracentrifuge separation of oil, micelle and sediment phases. During the 60-cm intestinal passage, over 40% of plant stanol esters were hydrolysed (P < 0.05) but around 30% of the infused free plant stanols (P < 0.05) and up to 40% of cholesterol (P < 0.05) were esterified in PJ after infusions. TAG in F1 favoured accumulation of plant stanol esters in the oil phase of the PJ aspirates as compared with respective values of F2 and F3 (P < 0.05 for both). About one third of free plant stanols of F3 had been esterified (P < 0.05) and 17% precipitated mainly in free form in the PJ aspirates (P < 0.05 compared with F1 and F2). In conclusion, DG- and TAG-oils had no profound superiority over each other as intestinal carriers regarding hydrolysis/esterification of administered plant stanol esters and cholesterol and their partition in oil, micellar and sediment phases in the PJ. The unesterified plant stanols experienced partial esterification and sedimentation during their intestinal passage, which might influence their biochemical properties in that segment of the gut where cholesterol is absorbed.

Dietary diacylglycerol induces the regression of atherosclerosis in rabbits

Recent studies of the relation between serum triacylglycerol concentration and the risk for coronary artery disease suggest that inefficient clearance of postprandial triacylglycerols promotes atherogenesis. We recently demonstrated that dietary diacylglycerol (DAG), rich in the 1,3-species, suppresses the postprandial increase in serum triacylglycerol levels compared with dietary triacylglycerol (TAG). Here, we investigated the effects of dietary DAG on atherosclerosis in rabbits with cholesterol-induced atherosclerosis. New Zealand White rabbits (n = 20) were fed a diet containing 3% lard and 1.3% cholesterol for 50 d to induce atherosclerotic lesions. Thereafter, the rabbits were assigned to 2 groups and fed 90 g/d nonpurified diet and orally administered 5 g DAG or TAG for an additional 34 d. Reference rabbits (n = 5) were fed only the nonpurified diet throughout the 84-d study. The area of atherosclerotic lesions and aortic lipid concentrations were significantly lower in DAG-fed rabbits compared with TAG-fed rabbits. The VLDL receptor and macrophage antigen-1 mRNA expression levels were significantly lower in DAG-fed rabbits than in TAG-fed rabbits. In the liver of DAG-fed rabbits, the triacylglycerol concentration was lower and the carnitine palmitoyltransferase activity higher than in TAG-fed rabbits. Stimulation of hepatic lipid catabolism might be related to the reduced lipid accumulation in the liver and aorta by reducing the release of triacylglycerol into the circulation. Thus, long-term consumption of DAG, which reduces postprandial lipemia, might be useful for the regression of atherosclerosis by stimulating hepatic lipid catabolism and thereby modulating monocyte/macrophage migration and aortic lipid accumulation.