Green tea catechin consumption enhances exercise-induced abdominal fat loss in overweight and obese adults.

This study evaluated the influence of a green tea catechin beverage on body composition and fat distribution in overweight and obese adults during exercise-induced weight loss. Participants (n = 132 with 107 completers) were randomly assigned to receive a beverage containing approximately 625 mg of catechins with 39 mg caffeine or a control beverage (39 mg caffeine, no catechins) for 12 wk. Participants were asked to maintain constant energy intake and engage in >or=180 min/wk moderate intensity exercise, including >or=3 supervised sessions per week. Body composition (dual X-ray absorptiometry), abdominal fat areas (computed tomography), and clinical laboratory tests were measured at baseline and wk 12. There was a trend (P = 0.079) toward greater loss of body weight in the catechin group compared with the control group; least squares mean (95% CI) changes, adjusted for baseline value, age, and sex, were -2.2 (-3.1, -1.3) and -1.0 (-1.9, -0.1) kg, respectively. Percentage changes in fat mass did not differ between the catechin [5.2 (-7.0, -3.4)] and control groups [-3.5 (-5.4, 1.6)] (P = 0.208). However, percentage changes in total abdominal fat area [-7.7 (-11.7, -3.8) vs. -0.3 (-4.4, 3.9); P = 0.013], subcutaneous abdominal fat area [-6.2 (-10.2, -2.2) vs. 0.8 (-3.3, 4.9); P = 0.019], and fasting serum triglycerides (TG) [-11.2 (-18.8, -3.6) vs. 1.9 (-5.9, 9.7); P = 0.023] were greater in the catechin group. These findings suggest that green tea catechin consumption enhances exercise-induced changes in abdominal fat and serum TG.

One-year ad libitum consumption of diacylglycerol oil as part of a regular diet results in modest weight loss in comparison with consumption of a triacylglycerol control oil in overweight Japanese subjects.

OBJECTIVE: The objective of this study was to investigate the effect of 1-year ad libitum consumption of diacylglycerol oil on body weight and serum triglyceride in Japanese men and women. DESIGN/SUBJECTS/INTERVENTION: In a 1-year double-blind, placebo-controlled parallel trial with clinic visits at month 0, 3, 6, 9, and 12, a total of 312 Japanese men (n=174) and women (n=138) (aged 22 to 73 years) with body mass index (calculated as kg/m(2)) > or =25 and/or fasting serum triglyceride level > or =150 mg/dL (1.70 mmol/L) (aged 22 to 73 years) were randomly assigned to the diacylglycerol (n=155) or triacylglycerol (n=157) group. Participants substituted their usual home cooking oil with the assigned test oils. MAIN OUTCOME MEASURES: Changes in anthropometrics and serum triglyceride level were monitored at 3-month intervals across a 12-month period. RESULTS: In the intention-to-treat analysis, body weight decreased significantly in the diacylglycerol group when compared to the triacylglycerol group (P=0.013). Changes in body weight and body mass index during the study period differed between the two groups by 0.87 kg (P=0.002) and 0.32 kg (P=0.002), respectively. Participants with higher initial body mass index or greater percentage of total fat intake as diacylglycerol exhibited greater reduction in body weight. Total energy intake and physical activity were not significantly different between the groups during the study. Serum triglyceride levels decreased significantly from values in individuals with hypertriglyceridemia, but did not differ between groups. CONCLUSIONS: Modest body weight reduction was observed after 1-year ad libitum consumption of diacylglycerol oil as part of a regular diet in comparison to that of triacylglycerol oil; weight loss was greatest in participants who were obese at baseline. The weight reduction observed in diacylglycerol group was attributed to the substitution of usual home cooking oil with diacylglycerol, because total energy intake and physical activity did not differ between groups.

Size-based distributions of postprandial lipoproteins in lymph and serum after oral administration of triacylglycerol and diacylglycerol oils in rats.

Several studies in humans and rodents suggest that postprandial serum triglyceride (TG) levels are decreased by a single oral administration of diacylglycerol (DAG) oil compared with administration of control triacylglycerol (TAG) oil. To gain further insight into the mechanisms underlying the metabolic properties of DAG in a postprandial state, we analyzed the size-based distributions of postprandial lipoproteins in the lymph and serum using gel filtration-based high-performance liquid chromatography. In thoracic duct lymph pooled for 3 h after oral administration of TAG or DAG, the size-based distributions of postprandial lymphatic lipoprotein-TG and -cholesterol levels did not differ significantly, suggesting that DAG did not affect the size of lipoprotein particles secreted from the small intestine. Serum lipoprotein-TG (60%) and -cholesterol levels (90%), however, were significantly different among fractions with a diameter of greater than 80 nm 1 to 2 h after the administration of DAG compared to TAG. In addition, there was a considerable, but nonsignificant, reduction in lipoprotein-TG levels (approximately 40%) in fractions with a diameter of 80 to 30 nm, suggesting that DAG-derived chylomicrons as well as DAG-derived chylomicron remnants were catabolized rapidly. In conclusion, dietary DAG reduced the amount of large-size lipoproteins in the serum, but did not affect the size distribution of lipoproteins produced in the small intestine. Thus, compared with TAG, dietary DAG may reduce the postprandial serum total TG levels.

Comparison of dietary triacylglycerol oil and diacylglycerol oil in protein kinase C activation.

The objective of the present study was to compare the effects of dietary diacylglycerol (DAG) oil with triacylglycerol (TAG) oil with a similar fatty acid composition (fatty acid chain range: C14-C22, C18 fatty acid chain: >90%) on protein kinase C (PKC) activation and on 1,2-DAG levels. Using male Wistar rats, no differences in cytosolic and membrane PKC activities in the lingual, esophageal, gastric, small intestinal, cecal, proximal colonic, and distal colonic mucosa were found between the 5% DAG and TAG oil groups, or between the 23% DAG and TAG oil groups after 1 month of feeding. The 1,2-DAG levels in the cecum and colon contents and in the feces and serum in male Wistar rats after a diet containing either 10% DAG or TAG oil feeding were similar between the groups. Moreover, exposure of Caco-2 cells to DAG and TAG oils had no effect on PKC activity in the membrane fraction, but 1,2-dioctanoyl glycerol composed of short-chain fatty acids (C8) did, suggesting the absence of an influence on PKC activity in DAG and TAG oils composed of long-chain fatty acids. In summary, the effects of DAG oil ingestion on PKC activity in the digestive tract and lingual mucosa, and on 1,2-DAG levels in the cecum and colon contents and in the feces and serum were similar to those observed for TAG oil ingestion.

WITHDRAWN: Combination of plant sterols and diacylglycerol oil lowers serum cholesterol and lipoprotein (a) concentrations in postmenopausal women with mild-to-moderate hypercholesterolemia.

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Effects of diacylglycerol oil on adiposity in obese children: initial communication.

Several studies have shown that diacylglycerol (DAG) oil may suppress accumulation of body fat in adults compared to triacylglycerol (TAG) oil. In this study, we investigated the effect of DAG oil as part of dietetic therapy in obese children. The participants were 11 male and female obese children who were under treatment at the outpatient clinic (four boys, seven girls, age: 7-17 years old). Daily-use cooking oil was changed to DAG oil, and the effects on abdominal fat areas, adipocytokines, and serum lipids were investigated. The total and subcutaneous fat areas significantly decreased in the 5th month after ingestion of DAG oil. Leptin was significantly lower than the initial level after ingestion of DAG oil. The ingestion of DAG oil decreased both the abdominal fat area and leptin in obese children, suggesting that DAG oil prevents obesity in children as well as in adults.

Effects of dietary diacylglycerol on the energy metabolism.

In the present study, we characterized diacylglycerol (DAG) oil in terms of energy metabolism by comparing oxygen consumption and respiratory quotient (RQ), as well as blood parameters, in rats after administration of emulsions containing either DAG or triacylglycerol (TAG) with similar fatty acid composition. Twelve male Wistar rats (250-280 g) were acclimatized, and then catheterized into the stomach, and held individually in Bollman restraining cages. After 24 hours fasting, each emulsion containing either DAG or TAG (10 g/kg body weight) was infused. Oxygen consumption and fat oxidation in the DAG group gradually increased after administration of the DAG emulsion and became significantly higher than those of the TAG group. RQ in both groups dropped after administration of emulsion, but the values of the DAG group were significantly lower than that of the TAG group. The postprandial serum triglyceride level was significantly increased from 60 minutes after administration in the TAG group, and 240 minutes in the DAG group, compared to the preprandial level. The serum triglyceride level tended to be lower in the DAG group than in the TAG group at 60 minutes and thereafter, and the statistical difference between the TAG and DAG groups was significant at 300 minutes after administration. These results suggest that DAG oil infusion might lead to higher energy expenditure and lipids oxidation compared to TAG oil with a similar fatty acid composition.

Effect of diacylglycerol on the development of impaired glucose tolerance in sucrose-fed rats.

The effects of DAG oil and TAG oil on impaired glucose tolerance in rats that were fed a diet containing high levels of sucrose were compared. Male Wistar rats (8 wk old and 32 wk old) were fed either high-sucrose (57.5% sucrose w/w) or control diets containing either 10% (w/w) DAG or TAG oil with a similar FA composition for 48 wk in 8-wk-old rats and for 24 wk in 32-wk-old rats. Plasma lipids, the size of the islets of Langerhans, and insulin, glucose, and adipocytokine levels were measured. An oral glucose tolerance test (OGTT) was carried out during the study period. For rats in both age groups that were fed a high-sucrose diet, the DAG oil group had lower plasma glucose and insulin response in an OGTT, and lower homeostasis model assessment-R levels, than the TAG oil group. Furthermore, in 8-wk-old rats that were fed a high-sucrose diet, the DAG oil group accumulated less visceral fat and showed suppressed decreases [corrected] of plasma adiponectin and [corrected] increases of plasma insulin, leptin, and the size of islet of Langerhans compared with the TAG oil group. No difference in the OGTT was found between the DAG and TAG oil groups in either age group of rats fed a control diet. In conclusion, these results suggest that DAG oil ingestion prevents the high-sucrose-diet-induced development of impaired glucose tolerance compared with TAG oil ingestion.

Metabolites of dietary triacylglycerol and diacylglycerol during the digestion process in rats.

The present study investigated the metabolic fate of dietary TAG and DAG and also their digestion products in the stomach and small intestine. A diet containing 10% TAG or DAG oil, enriched in 1,3-DAG, was fed to Wistar rats ad libitum for 9 d. After 18 h of fasting, each diet was re-fed ad libitum for 1 h. The weights of the contents of the stomach and small intestine were measured, and the acylglycerol and FFA levels were analyzed by GC at 0, 1, and 4 h after the 1-h re-feeding. The amounts of re-fed diet ingested and the gastric and small intestinal content were not different between the two diet groups. In the TAG diet group, the main products were TAG and DAG, especially 1(3),2-DAG. In addition, 1,3-DAG and 1(3)-MAG were present in the stomach, and the 1,3-DAG levels increased over time after the re-feeding period. In the DAG diet group, the main products in the stomach were DAG, MAG, FFA, and TAG. There were significantly greater amounts of 1,3-DAG, 1(3)-MAG, and FFA in the DAG diet group in the stomach compared with the TAG diet group. The amount of FFA in the stomach relative to the amount of ingested TAG plus DAG in the DAG diet group was higher than that in the TAG diet group. Acylglycerol and FFA levels were considerably lower in the small intestine than in the stomach. These results indicate that, in the stomach, where acyl migration might occur, the digestion products were already different between TAG and DAG oil ingestion, and that DAG might be more readily digested by lingual lipase compared with TAG. Furthermore, almost all of the dietary lipid was absorbed, irrespective of the structure of the acylglycerol present in the small intestine.

Effects of diacylglycerol ingestion on postprandial hyperlipidemia in diabetes.

BACKGROUND: We previously reported that diacylglycerol (DAG) as compared with triacylglycerol (TAG) suppressed increases in postprandial lipids in healthy volunteers. This study was to investigate the effects of DAG on postprandial lipids, particularly remnant lipoproteins in diabetics. METHODS: Emulsified DAG oil or TAG oil with a fatty acid composition similar to DAG oil was orally administered (30 g fat/m2 of body surface) to moderately controlled six diabetics, with hemoglobin A1c (HbA1c) below 8%, after fasting for at least 12 h in a randomized crossover manner. Serum cholesterol and TAG, lipids in remnant-like particles (RLP), and other lipid parameters including serum ketone bodies were measured prior to and 2, 4, and 6 h after fat loading. RESULTS: DAG loading significantly suppressed increases in postprandial serum TAG and lipids in RLP as compared with TAG loading. The incremental area under the curve (IAUC) for serum TAG and that for lipids in RLP with DAG loading were also significantly smaller than those with TAG loading. However, changes in serum levels of insulin, free fatty acids, and ketone bodies during fat loading were essentially the same for DAG and TAG. CONCLUSIONS: This pilot study suggests that substituting DAG intake for TAG may be beneficial to moderately controlled diabetics due to its effect in reducing postprandial hyperlipidemia.

Biosynthesis of acylceramide in murine epidermis: characterization by inhibition of glucosylation and deglucosylation, and by substrate specificity.

We have investigated the physiological significance of the glucosylation of ceramides and the subsequent deglucosylation of glucosylceramide in the synthetic pathway of acylceramide. In this metabolic pathway using [14C]-serine in organ culture, newborn murine (BALB/c) epidermis synthesizes several types of ceramides, including acylceramide, as analyzed by thin-layer chromatography. When conduritol-B-epoxide, a specific inhibitor of beta-glucocerebrosidase, was added to the culture medium, the synthesis of acylceramide was significantly suppressed in concert with a significant increase in acylglucosylceramide. Furthermore, addition of d-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol, an inhibitor of glucosyltransferase, also specifically abolished the synthesis of acylceramide whereas non-acylated ceramides were relatively less affected. We further determined whether the physiological substrate of glucosyltransferase is omega-hydroxyceramide (C30) or non-omega-hydroxylated ceramides. Of those, only non-omega-hydroxylated ceramides proved to be good substrates for glucosyltransferase in vitro. Our parallel in vitro study also demonstrated that murine epidermis contains enzymatic activity by which omega-hydroxyglucosylceramide or omega-hydroxyceramide can be converted to acylglucosylceramide or acylceramide. Collectively, these findings indicate that the majority of acylceramides found in the stratum corneum may be synthesized through a distinct sequence of enzymatic reactions consisting of the glucosylation of ceramides by glucosyltransferase, omega-hydroxylation of glucosylceramide, the acylation of omega-hydroxyglucosylceramide (possibly by an omega-acyltransferase), and the deglucosylation of acylglucosylceramide by beta-glucocerebrosidase.

Nutritional characteristics of DAG oil.

Excess calorie intake in industrialized countries has prompted development of fat substitutes and other lower-calorie dietary items to enhance health. DAG cooking oils, with a 1,3 configuration, taste and have the texture of commonly used TAG cooking oils. Because they are not hydrolyzed to 2-MAG in the gut, the absorption and metabolism of DAG oil differs from that of TAG. Among the physiological differences are lower postprandial lipemia and an increased proportion of FA being oxidized instead of stored. Preliminary studies suggest that these differences in energy partitioning between DAG and TAG may be usefully exploited to reduce the amount of fat stored from cooking oil and oil components of food items. Over 70 million bottles of DAG oil have been sold in Japan since its introduction in February 1999, and the product is being test-marketed in the United States. It is hoped that wider use of DAG oil may provide one additional means of preventing obesity.

Consumption of diacylglycerol oil as part of a reduced-energy diet enhances loss of body weight and fat in comparison with consumption of a triacylglycerol control oil.

BACKGROUND: Diacylglycerol is a natural component of edible oils that has metabolic characteristics that are distinct from those of triacylglycerol. OBJECTIVE: We assessed the efficacy of an oil containing mainly 1,3-diacylglycerol in reducing body weight and fat mass when incorporated into a reduced-energy diet. DESIGN: The study was a randomized, double-blind, parallel intervention trial that was conducted at an outpatient clinical research center. The subjects (n = 131) were overweight or obese men (waist circumference > or = 90 cm) and women (waist circumference > or = 87 cm). Food products (muffins, crackers, soup, cookies, and granola bars) containing diacylglycerol or triacylglycerol oil and having the same fatty acid composition were incorporated into a reduced-energy diet (2100-3350-kJ/d deficit) for 24 wk. Percentages of change in body weight, fat mass, and intraabdominal fat area were assessed. RESULTS: In an intention-to-treat analysis, body weight and fat mass decreased significantly more in the diacylglycerol group than in the triacylglycerol group (P = 0.025 and 0.037, respectively). By the end of the trial, mean body weight had decreased 3.6% and 2.5% in the diacylglycerol and triacylglycerol groups, respectively. Fat mass decreased 8.3% and 5.6% in the diacylglycerol and triacylglycerol groups, respectively. CONCLUSION: Foods containing diacylglycerol oil promoted weight loss and body fat reduction and may be useful as an adjunct to diet therapy in the management of obesity.

Dietary diacylglycerol suppresses high fat diet-induced hepatic fat accumulation and microsomal triacylglycerol transfer protein activity in rats.

We have recently shown that the long-term ingestion of dietary diacylglycerol (DAG) mainly containing 1,3-isoform reduces body fat accumulation in humans as compared to triacylglycerol (TAG) with the same fatty acid composition. The fat reduction in this human experiment was most pronounced in visceral fat and hepatic fat. Recent animal studies have also indicated that dietary DAG induces alteration of lipid metabolism in the rat liver. In the present study, the dietary effects of DAG on high fat diet-induced hepatic fat accumulation and hepatic microsomal triglyceride transfer protein (MTP) activity were examined in comparison with those of TAG diet in rats. When the TAG oil content was increased from 10 to 30 g/100 g diet, hepatic TAG concentration, hepatic MTP activity and MTP large subunit mRNA levels were significantly increased after 21 days. However, when the dietary TAG oil (30 g/100 g diet) was replaced with the same concentration of DAG oil with the same fatty acid composition, the increase of the TAG concentration and the MTP activity in the liver were significantly less and the mRNA levels remained unchanged. The MTP activity levels correlated significantly with hepatic TAG concentration.These results showed that dietary DAG may suppress high fat diet-induced MTP activity in the liver, and indicated the possibility that hepatic TAG concentration may regulate hepatic MTP activity.