Effect of dietary fat level and sesamin on the polyunsaturated fatty acid metabolism in rats

In this study, we examined the effects of sesamin and vegetable oil on the concentrations of polyunsaturated fatty acid (PUFA) and lipids (triacylglycerol, free cholesterol, and phospholipid), and beta-oxidation enzyme activities in the rat liver. Rats were fed a diet containing 5% (low-fat diet) or 20% (high-fat diet) salad oil (rapeseed oil: soybean oil, 7:3) with or without sesamin (0.5% w/w) for 4 wk. As a result, the concentrations of linoleic acid (LA, n-6), alpha-linolenic acid (ALA, n-3), and total PUFA in the liver increased significantly as the result of the high-fat diet. In the high-fat diet groups, sesamin administration decreased the concentrations of LA, ALA, and total PUFA to almost the same level as the low-fat diet group, while it increased the concentrations of dihomo-gamma-linolenic acid (DGLA, n-6) and arachidonic acid (AA, n-6). The activities of carnitine acyltransferase and acyl-CoA dehydrogenase in liver mitochondria were enhanced by the intake of the high-fat diet, and were further enhanced by the administration of sesamin. Peroxisomal acyl-CoA oxidase activity was also enhanced by sesamin, while it was not affected by the dietary fat level. These results suggest that sesamin suppressed the increase of hepatic PUFA concentration caused by feeding the high-fat diet through enhancing the enzyme activities of fatty acid beta-oxidation and PUFA metabolism from LA and ALA.     

Snack chips fried in corn oil alleviate cardiovascular disease risk factors when substituted for low-fat or high-fat snacks

BACKGROUND: The perception that all high-fat snacks are unhealthy may be wrong. OBJECTIVE: We aimed to assess whether replacing low-fat and high-fat snacks with snacks rich in polyunsaturated fatty acids (PUFAs) and low in saturated and trans fatty acids would improve cardiovascular health. DESIGN: Thirty-three adults participated in a randomized crossover trial of 3 controlled feeding phases of 25 d each in which a different type of snack was provided: low-fat (30.8% of energy from fat, 5.2% of energy from PUFAs), high-PUFA (36.3% of energy from fat, 9.7% of energy from PUFAs), or high-fat (37.9% of energy from fat, 5.8% of energy from PUFAs) snack. RESULTS: Each diet reduced LDL- and total cholesterol concentrations, but reductions were greater with the low-fat and the high-PUFA diets than with the high-fat diet: LDL cholesterol (11.8% and 12.5% compared with 8.8%, respectively; P = 0.03 and 0.01), total cholesterol (10.5% and 10.7% compared with 7.9%, respectively; P = 0.03 and 0.02). The high-PUFA diet tended to reduce triacylglycerol concentrations (9.4%; P = 0.06), and this change was greater than that with the low-fat (P = 0.028) and high-fat (P = 0.0008) diets. CONCLUSIONS: These data show that snack type affects cardiovascular health. Consuming snack chips rich in PUFA and low in saturated or trans fatty acids instead of high-saturated fatty acid and trans fatty acid or low-fat snacks leads to improvements in lipid profiles concordant with reductions in cardiovascular disease risk.     

The effect of carbohydrate and fat variation in euenergetic diets on postabsorptive free fatty acid release

Diet composition and energy content modulate free fatty acid (FFA) release. The aim of this study was to evaluate the dose-response effects of euenergetic variations in dietary carbohydrate and fat content on postabsorptive FFA release. The rate of appearance (Ra) of palmitate was measured by infusion of [2,2-2H2]palmitate after an overnight fast in six healthy men on three separate occasions, i.e. after 7 d on euenergetic control, high-carbohydrate and high-fat diets. The protein content and composition was identical for each diet. Postabsorptive plasma fatty acid concentrations were not different between the high-carbohydrate and control diets (0.36 (se 0.07) v. 0.43 (se 0.04) mmol/l), but were increased after the high-fat diet (0.75 (se 0.09) mmol/l, (P<0.01 compared with the other diets). Ra palmitate was not different between the high-carbohydrate and control diets (1.36 (se 0.20) v. 1.47 (se 0.15) micromol/kg per min). However, Ra palmitate was increased to 2.36 (se 0.26) micromol/kg per min after the high-fat diet (P<0.01 compared with the other diets). The fatty acid flux and whole-body fat oxidation were not affected by the high-carbohydrate diet compared with the control diet, but were increased by 67 and 47 % respectively, on the high-fat diet (P<0.01 compared with the other diets). A euenergetic high-fat diet results in increased postabsorptive FFA release and fat oxidation, whereas a euenergetic high-carbohydrate diet does not affect these variables of fat metabolism.     

Effects of cysteine-containing compounds on biosynthesis of triacylglycerol and cholesterol and anti-oxidative protection in liver from mice consuming a high-fat diet

Effects of n-acetyl cysteine (NAC), s-ethyl cysteine (SEC), s-propyl cysteine (SPC) and cysteine on enzymes participating in biosynthesis of TAG and cholesterol, and antioxidant protection in liver from mice consuming a high-saturated fat diet was examined. The high-fat diet provided 70 % fat energy, in which saturated fat was 55 % of total fat. NAC, SEC, SPC or cysteine, each agent at 1 g/l, was directly added into the drinking water as a supplement for 4 weeks. Results showed high saturated fat significantly increased hepatic TAG and total cholesterol contents (P < 0.05) via enhancing the activity and mRNA expression of malic enzyme, fatty acid synthase and 3-hydroxy-3-methylglutaryl coenzyme A reductase (P < 0.05). The intake of NAC, SEC or SPC significantly decreased TAG and total cholesterol levels (P < 0.05) via lowering the activity and mRNA expression of these three lipogenic-related enzymes (P < 0.05). NAC, SEC or SPC treatment also significantly suppressed high saturated fat-induced hepatic mRNA expression of sterol regulatory element-binding protein (SREBP)-1c and SREBP-2 (P < 0.05). High saturated fat decreased hepatic content of glutathione, and the activity of catalase and glutathione peroxidase (P < 0.05). The intake of NAC, SEC or SPC significantly increased hepatic glutathione content (P < 0.05), restored the activity and mRNA expression of glutathione peroxidase, and alleviated the high saturated fat-induced oxidative stress (P < 0.05). These results support that NAC, SEC and SPC are potent agents for affecting hepatic biosynthesis of TAG and cholesterol, and protecting liver against high saturated fat-associated oxidative damage.     

Gender influence on plasma triacylglycerol response to meals with different monounsaturated and saturated fatty acid content

OBJECTIVE: Both gender and meal fatty acid composition modulate postprandial triacylglycerol (TAG) metabolism, but little information exists on their interaction. We compared postprandial TAG concentrations in men and women after test meals differing in the proportion of monounsaturated (MUFA) and saturated fatty acids (SFA). SUBJECTS: Nine men (body mass index, BMI: 24.5+/-2.3 kg/m(2)) (mean+/-s.d.) and 10 premenopausal women (BMI: 21.2+/-1.7 kg/m(2)), young and healthy, habituated to a relatively high MUFA diet. DESIGN: Plasma responses were studied after subjects consumed two meals, each providing 60 g of fat and 4.7 MJ, on different occasions: one meal was rich in MUFA (MUFA meal: 40 g MUFA; 12 g SFA) and the other meal was rich in SFA (SFA meal: 20 g MUFA; 32 g SFA). The total body and abdominal fat mass were assessed by dual energy X-ray absorptiometry. RESULTS: Fasting plasma TAG concentration did not differ between meals or genders. No gender differences were observed in either total body or abdominal fat mass. The area under the plasma concentration vs time curve was on average 60% higher (P<0.001) in men than women. Repeated measures ANOVA showed a significant effect of meal x time interaction in men (P<0.001) but not in women (P=0.84). In men, maximal plasma TAG occurred at 4 h and was significantly greater after the MUFA meal (2.10+/-0.20 mmol/l) (mean+/-s.e.m.) than after the SFA meal (1.66+/-0.19 mmol/l) (P=0.01). TAG concentration at 5 h was also significantly greater after the MUFA meal. In women, the patterns of TAG responses were identical after the MUFA and SFA meals. CONCLUSIONS: This study provides evidence that gender influences postprandial TAG concentrations when meal fatty acid composition is altered.     

Total dietary fat and fatty acid content modifies plasma phospholipid fatty acids,desaturase activity indices,and urinary prostaglandin E in women

Compared with diets high in fat, low-fat diets are associated with reduced risk of cardiovascular disease. We hypothesized that a low-fat (LF) (20% fat) and an LF high–omega-3 (n-3) fatty acid diet (LFn3) (23% fat with 3% as α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid [DHA]) would enhance n-3 composition of plasma phospholipid fatty acid and reduce urinary prostaglandin E₂ (PGE₂) relative to a high-fat diet (HF) (40% fat) and that these changes would be associated with alterations in δ5 desaturase (D5D) and δ6 desaturase (D6D) activity. Phospholipid fatty acids and urinary PGE₂ were measured, and D5D and D6D activity indices calculated in a crossover trial in 17 postmenopausal women fed each of 3 test diets (HF, LF, and LFn3) for 8-week feeding periods. Desaturase activity indices were calculated as D5D, 20:4n-6/20:3n-6, and D6D, 20:3n-6/18:2n-6. Plasma phospholipid fatty acid, α-linolenic acid, eicosapentaenoic acid, docosapentaenoic acid (DPA), DHA, and total n-3 fatty acids increased, whereas linoleic acid and arachidonic acid decreased with consumption of LFn3. The LF resulted in enhanced arachidonic acid and DHA. High fat reduced D6D, whereas both HF and LF increased D5D. Urinary PGE₂ was reduced in response to both the LF and LFn3 diets. Low-fat diets, with or without long-chain n-3 fatty acids, promote positive health effects due in part to favorable alteration of plasma phospholipid fatty acid profiles and modification in desaturase activity indices, suggesting that the type and amount of fat consumed are modifiable risk factors for the prevention of cardiovascular disease.     

Effects of trans-10,cis-12 CLA on liver size and fatty acid oxidation under energy restriction conditions in hamsters

Objective

Little evidence exists concerning the effects of trans-10,cis-12 conjugated linoleic acid (CLA) under energy restriction. Thus, the effects of this CLA isomer on adipose tissue size, liver composition, as well as on expression and activity of carnitine-palmitoyl transferase I (CPT-I) and acyl CoA oxidase (ACO), in hamsters fed an energy-restricted diet were analyzed.

Methods

Hamsters were fed a high-fat diet for 7 wk and then subjected to 25% energy-restricted diets supplemented with 0.5% linoleic acid or 0.5% trans-10,cis-12 CLA for 3 wk. Serum insulin, free-triiodothyronine and non-esterified fatty acid levels, liver triacylglycerol, protein and water contents, and CPT-I, ACO, and Peroxisome proliferator-activated receptor alpha (PPARα) expressions and enzyme activities were assessed.

Results

Energy restriction reduced liver size, serum levels of insulin, free-triiodothyronine, and non-esterified fatty acid and increased CPT-I activity. Liver composition was not modified. No differences were found between both restricted groups, with the exception of CPT-I and ACO oxidative enzyme activities, which were greater in hamsters fed the CLA diet.

Conclusions

Energy restriction does not cause trans-10,cis-12 CLA to induce liver hyperplasia. Although this CLA isomer increases liver CPT-I and ACO activities, this effect does not result in reduced hepatic triacylglyerol content or decreased adipose tissue size. Consequently, this CLA isomer seems not to be a useful tool for inclusion in body weight loss strategies followed during obesity treatment.     

Is the effect of prior exercise on postprandial lipaemia the same for a moderate-fat meal as it is for a high-fat meal?

Moderate-intensity exercise can lower the TAG response to a high-fat meal; however, the British diet is moderate in fat, and no study to date has compared the effect of such exercise on responses to high-fat and moderate-fat meals. The present work investigated the effect of brisk walking performed 13?h before intake of both high-fat and moderate-fat meals on postprandial plasma TAG concentrations. Eight inactive, overweight men completed four separate 2?d trials, i.e. rest (Con) or a 90-min treadmill walk (Ex) on the evening of day 1, followed by the ingestion of a moderate-fat (Mod) or high-fat (High) meal on the morning of day 2. High-fat meals contained 66?% of total energy as fat, while the percentage was 35?% for moderate-fat meals; both the meals were, however, isoenergetic. On day 2, venous blood was sampled in the fasted state, 30 and 60?min after ingesting the test meal and then hourly until 6?h post-meal. Exercise reduced plasma TAG concentrations significantly (P?相似文献   

Short-term, high-fat diets lower circulating leptin concentrations in rats

BACKGROUND: Leptin is produced in proportion to body fat mass and can act on the brain to induce satiety and regulate adipose tissue mass; factors other than adipose tissue mass may influence circulating leptin concentrations. OBJECTIVE: We explored the possibility that short-term, moderately high-fat diets induce weight gain by producing inappropriately low circulating leptin concentrations. DESIGN: Female Hooded Wistar rats were fed either a moderately high-fat diet or control diet. Body weight, energy intake, body composition, and fasting plasma leptin were compared after 4 and 14 wk of dietary treatment. RESULTS: After 4 wk, abdominal fat mass was 38% greater in rats fed the high-fat diet than in those fed the control diet (P < 0.01). However, plasma leptin concentrations were 24% lower in animals fed the high-fat diet (P < 0.05), resulting in significantly lower plasma leptin concentrations per unit abdominal fat mass than in control animals (P < 0.005). From 4 to 14 wk, animals fed the high-fat diet gained twice as much weight and consumed 32 kJ/d more than controls (both P < 0.05). At 14 wk, plasma leptin concentrations per unit abdominal fat mass were 27% lower in rats fed the high-fat diet (P = 0.058) and there was a significant negative association between leptin concentrations per unit abdominal fat mass and body weight (r = 0.44, P < 0.05). CONCLUSIONS: In the short term, a moderately high-fat diet is associated with lower than expected circulating leptin concentrations, which correlate with a higher body weight. A high-fat diet may therefore contribute to weight gain by reducing leptin secretion in adipose tissue.     

Dietary marine algae (Schizochytrium sp.) increases concentrations of conjugated linoleic, docosahexaenoic and transvaccenic acids in milk of dairy cows.

Modification of milk fat to contain long-chain (n-3) fatty acids and increased concentrations of conjugated linoleic acid has potential for improving health of consumers. Natural modification of milk through nutritional manipulation of diets for dairy cows is preferable to post-harvest modification. The objectives of this study were to increase the concentrations of beneficial fatty acids in milk fat by feeding a diet rich in (n-3) fatty acids from algae to dairy cows. Cows were fed a control diet, a diet containing algae (Schizochytrium sp.) protected against ruminal biohydrogenation, or a diet containing unprotected algae for 6 wk. Feed intake and milk production were recorded daily. Milk samples were obtained weekly for analysis of milk composition and profile of fatty acids. Percentage of fat in milk of cows fed algae was lower (P < 0.01) than in milk from cows fed the control diet; however, energy-corrected milk production did not differ (P > 0.05). Inclusion of algae in diets decreased (P < 0.01) feed intake. Milk fat from cows fed algae contained greater (P < 0.01) concentrations of conjugated linoleic acid, (n-3) fatty acids (particularly docosahexaenoic acid), and transvaccenic acid. Concentrations of docosahexaenoic acid were greater (P < 0.01) in milk fat from cows fed protected algae compared to milk fat from cows fed unprotected algae. Milk fat from cows fed algae contained lower (P < 0.05) concentrations of total saturated fatty acids compared to cows fed the control diet. In conclusion, milk fat can be modified through nutritional management of dairy cows to provide more favorable fatty acids for consumers.     

Low-fat and high-monounsaturated fatty acid diets decrease plasma cholesterol ester transfer protein concentrations in young, healthy, normolipemic men

BACKGROUND: Cholesterol ester transfer protein (CETP) mediates the transfer of cholesteryl esters from HDL to apolipoprotein (apo) B-containing lipoproteins. The possible atherogenic role of this protein is controversial. Diet may influence plasma CETP concentrations. OBJECTIVE: The objective was to determine whether the changes in plasma lipids observed after consumption of 2 lipid-lowering diets are associated with changes in plasma CETP concentrations. DESIGN:: We studied 41 healthy, normolipidemic men over 3 consecutive 4-wk dietary periods: a saturated fatty acid-rich diet (SFA diet: 38% fat, 20% saturated fat), a National Cholesterol Education Program Step I diet (NCEP Step I diet: 28% fat, 10% saturated fat), and a monounsaturated fatty acid-rich diet (MUFA diet: 38% fat, 22% monounsaturated fat). Cholesterol content (27.5 mg/MJ) was kept constant during the 3 periods. Plasma concentrations of total, LDL, and HDL cholesterol; triacylglycerol; apo A-I and B; and CETP were measured at the end of each dietary period. RESULTS: Compared with the SFA diet, both lipid-lowering diets significantly decreased plasma total and LDL cholesterol, apo B, and CETP. Only the NCEP Step I diet lowered plasma HDL cholesterol. Positive, significant correlations were found between plasma CETP and total (r = 0.3868, P < 0.0001) and LDL (r = 0.4454, P < 0.0001) cholesterol and also between changes in CETP concentrations and those of total (r = 0.4543, P < 0.0001) and LDL (r = 0.4554, P < 0.0001) cholesterol. CONCLUSIONS: The isoenergetic substitution of a high-saturated fatty acid diet with an NCEP Step I or a high-monounsaturated fatty acid diet decreases plasma CETP concentrations.     

Indirect measurement of the production of plasma triacylglycerols by horses given a high-fat diet

The hypothesis tested was that the feeding of extra fat to horses would raise the production of plasma triacylglycerols (TAG). To measure TAG secretion, the indirect Triton method was used. Six adult horses were given a low-fat control or a high-fat diet according to a crossover design. In keeping with our earlier work, the high-fat diet lowered fasting plasma TAG concentrations by an average of 42% and raised post-heparin total lipoprotein lipase activity by 79%. The rate of increase in plasma TAG concentration after Triton administration was 49% lower when the horses were fed the high-fat diet instead of the low-fat control diet. Thus, the hypothesis is rejected. It is suggested that the dose of Triton used in the study might have been too low to fully depress lipoprotein lipase activity, leading to an outcome of the study that was opposite to that expected.     

Baseline plasma C-reactive protein concentrations influence lipid and lipoprotein responses to low-fat and high monounsaturated fatty acid diets in healthy men

To date, no studies have compared the effects of consuming a low-fat diet and a high monounsaturated fatty acid (MUFA) diet, under unrestricted energy intake conditions, on plasma C-reactive protein (CRP) concentrations. Men [n = 61; 37.5 +/- 11.5 y old (mean +/- SD), mean BMI 29.0 +/- 5.0 kg/m2] were randomly assigned to consume ad libitum a moderately low-fat diet (25.8% of energy intake from fat) or a high-fat diet rich in MUFA (40.1% of energy intake from fat, 22.5% from MUFA) for 6-7 wk. Plasma CRP concentrations were measured using a highly sensitive assay. Neither diet affected the plasma CRP concentration. However, baseline CRP concentrations predicted lipoprotein/lipid responsiveness to the experimental diets. After intake of the low-fat diet, plasma total and VLDL-triglyceride (TG) concentrations were increased in the subgroup with high CRP concentrations (P < 0.05 and P < 0.01, respectively) whereas they were reduced in the subgroup with low CRP concentrations at baseline (P < 0.01 for both). The high-MUFA diet reduced plasma TG, VLDL-TG, and VLDL cholesterol only in the subgroup with low CRP at baseline (P < 0.0001). In conclusion, the low-fat diet and the high-MUFA diet did not affect plasma CRP concentrations. However, baseline plasma CRP concentrations may modulate the diet-induced changes in plasma lipid and lipoprotein concentrations.     

Effects of diets high in saturated fatty acids, canola oil, or safflower oil on platelet function, thromboxane B2 formation, and fatty acid composition of platelet phospholipids.

Platelet function and fatty acid composition were investigated in 30 healthy male subjects who ate a controlled-saturated-fatty-acid (baseline) diet for 3 wk and then consumed either safflower oil or canola oil as a major fat source for 8 wk. Fatty acid composition of platelet phospholipids reflected changes in dietary fatty acid composition. Compared with baseline a 35% decrease (P less than 0.05) in arachidonic acid was observed in platelet phospholipids of the canola-oil diet group while long chain n-3 fatty acids rose 7-26% (P greater than 0.05). Compared with baseline both unsaturated-fatty-acid diets reduced platelet aggregation at 3 wk of oil-based diet feeding (P less than 0.01) whereas only canola oil influenced platelet function (lowered ATP secretion) at 8 wk (P less than 0.01). No significant difference was observed in thromboxane B2 concentrations between oil-treatment groups at 8 wk. Both oil-based diets had short-term beneficial effects on platelet function but the effect of canola oil persisted longer.     

Effect of dietary fatty acids on the postprandial fatty acid composition of triacylglycerol-rich lipoproteins in healthy male subjects

OBJECTIVE: The aim of the present study was to investigate the effect of trans-18:1 isomers compared to other fatty acids, especially saturates, on the postprandial fatty acid composition of triacylglycerols (TAG) in chylomicrons and VLDL. DESIGN: A randomised crossover experiment where five interesterified test fats with equal amounts of palmitic acid (P fat), stearic acid (S fat), trans-18:1 isomers (T fat), oleic acid (O fat), or linoleic acid (L fat) were tested. SUBJECTS: A total of 16 healthy, normolipidaemic males (age 23+/-2 y) were recruited. INTERVENTIONS: The participants ingested fat-rich test meals (1 g fat per kg body weight) and the fatty acid profiles of chylomicron and VLDL TAG were followed for 8 h. RESULTS: The postprandial fatty acid composition of chylomicron TAG resembled that of the ingested fats. The fatty acids in chylomicron TAG were randomly distributed among the three positions in accordance with the distributions in test fats. Calculations of postprandial TAG concentrations from fatty acid data revealed increasing amounts up to 4 h but lower response curves (IAUC) for the two saturated fats in accordance with previous published data. The T fat gave results comparable to the O and L fats. The test fatty acids were much less reflected in VLDL TAG and there was no dietary influence on the response curves. CONCLUSIONS: The fatty acid composition in the test fats as well as the positional distributions of these were maintained in the chylomicrons. No specific clearing of chylomicron TAG was observed in relation to time.     

Reduced adiposity in bitter melon (Momordica charantia) fed rats is associated with lower tissue triglyceride and higher plasma catecholamines

Slower weight gain and less visceral fat had been observed when rats fed a high-fat diet were supplemented with freeze-dried bitter melon (BM) juice; the metabolic consequences and possible mechanism(s) were further explored in the present study. In a 4-week experiment, rats were fed a low-fat (70 g/kg) or a high-fat (300 g/kg) diet with or without BM (7.5 g/kg or 0.75%). BM-supplemented rats had lower energy efficiency, visceral fat mass, plasma glucose and hepatic triacylglycerol, but higher serum free fatty acids and plasma catecholamines. In the second experiment, 7-week BM supplementation in high-fat diet rats led to a lowering of hepatic triacylglycerol (P<0.05) and steatosis score (P<0.05) similar to those in rats fed a low-fat diet. BM supplementation did not affect serum and hepatic cholesterol. However, plasma epinephrine and serum free fatty acid concentrations were increased (P<0.05). In the third experiment, BM(7.5 and 15 g/kg) and 1.5 % BM lowered triacylglycerol concentration in red gastrocnemius and tibialis anterior (P<0.05) muscle, but a dose-response effect was not observed. These data suggest that chronic BM feeding leads to a general decrease in tissue fat accumulation and that such an effect is mediated in part by enhanced sympathetic activity and lipolysis. BM or its bioactive ingredient(s) could be used as a dietary adjunct in the control of body weight and blood glucose.     

The major green tea polyphenol, (-)-epigallocatechin-3-gallate, inhibits obesity, metabolic syndrome, and fatty liver disease in high-fat-fed mice

In this study, we investigated the effects of the major green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), on high-fat-induced obesity, symptoms of the metabolic syndrome, and fatty liver in mice. In mice fed a high-fat diet (60% energy as fat), supplementation with dietary EGCG treatment (3.2 g/kg diet) for 16 wk reduced body weight (BW) gain, percent body fat, and visceral fat weight (P < 0.05) compared with mice without EGCG treatment. The BW decrease was associated with increased fecal lipids in the high-fat-fed groups (r(2) = 0.521; P < 0.05). EGCG treatment attenuated insulin resistance, plasma cholesterol, and monocyte chemoattractant protein concentrations in high-fat-fed mice (P < 0.05). EGCG treatment also decreased liver weight, liver triglycerides, and plasma alanine aminotransferase concentrations in high-fat-fed mice (P < 0.05). Histological analyses of liver samples revealed decreased lipid accumulation in hepatocytes in mice treated with EGCG compared with high-fat diet-fed mice without EGCG treatment. In another experiment, 3-mo-old high-fat-induced obese mice receiving short-term EGCG treatment (3.2 g/kg diet, 4 wk) had decreased mesenteric fat weight and blood glucose compared with high-fat-fed control mice (P < 0.05). Our results indicate that long-term EGCG treatment attenuated the development of obesity, symptoms associated with the metabolic syndrome, and fatty liver. Short-term EGCG treatment appeared to reverse preexisting high-fat-induced metabolic pathologies in obese mice. These effects may be mediated by decreased lipid absorption, decreased inflammation, and other mechanisms.     

Effects of conjugated linoleic acid on skeletal muscle triacylglycerol metabolism in hamsters

OBJECTIVE: The present work evaluated the effects of conjugated linoleic acid (CLA) on various aspects of triacylglycerol metabolism in skeletal muscle to determine the potential involvement of this tissue in the effect of CLA to decrease body fat. METHODS: Animals were randomized to three groups that were fed atherogenic diets that provided different amounts of trans-10,cis-12 CLA (0%, 0.5%, or 1%) for 6 wk. Muscle triacylglycerol, protein, water, glycogen, and DNA contents and fatty acid profile in triacylglycerols were analyzed. Lipoprotein lipase and carnitine palmitoyltransferase-I (CPT-I) activities were assessed. Triacylglycerol, glucose, and insulin concentrations were evaluated in serum. RESULTS: The high dose of CLA increased food efficiency and gastrocnemius muscle weight. CLA feeding resulted in decreased muscle triacylglycerol content without changes in protein, water, glycogen, and DNA contents or in cell size (protein/DNA ratio) and produced decreased lipoprotein lipase activity and increased CPT-I activity. No differences were found between CLA doses. CLA feeding led to the saturation of stored triacylglycerols. CONCLUSIONS: Decreased fatty acid uptake and increased fatty acid oxidation can contribute to the decreased muscle triacylglycerol content observed in hamsters fed the CLA diets. The increase in muscle fatty acid beta-oxidation might ultimately prevent storage of triacylglycerols in adipose tissue. Nevertheless, the lack of matching of lipoprotein lipase and CPT-I modifications makes it difficult to ensure that skeletal muscle is responsible, at least in part, for the effect of CLA on decreasing body fat; thus, further research is needed.     

Total fat intake modifies plasma fatty acid composition in humans

Plasma fatty acid composition reflects dietary fatty acids. Whether the total fat content of the diet alters the fatty acid composition of plasma phospholipid, cholesteryl ester, triacylglycerol and free fatty acids is unknown. To evaluate the effects of low versus high fat diets on plasma fatty acids, a 12-wk, randomized, crossover, controlled feeding trial was conducted in healthy men and women with isoenergic low fat (20% energy) and high fat (45% energy) diets containing constant proportions of fatty acids. Ten subjects consumed one experimental diet for 28 d, their usual diet for 4 wk and the alternate experimental diet for 28 d. Endpoint measures of plasma fatty acids were determined at the end of each experimental period. The effects of the two diets were compared within subjects by analysis of variance. Plasma fatty acids (%) varied in response to total dietary fat with significantly greater total polyunsaturated fat, (n-6) and 18:2(n-6) levels in phospholipids and cholesteryl esters after high fat dietary consumption. The low fat diet was associated with significantly greater total (n-3) fatty acids, 20:5(n-3) and 22:6(n-3) levels in plasma phospholipid fatty acids and cholesteryl esters. Consumption of a low fat diet alters fatty acid patterns in a manner similar to that observed with feeding of (n-3) long-chain fatty acids. This change is likely related to decreased competition for the enzymes of elongation and desaturation, with reduced total intake of 18:2(n-6) favoring elongation and desaturation of available (n-3) fatty acids.     

Exercise of low energy expenditure along with mild energy intake restriction acutely reduces fasting and postprandial triacylglycerolaemia in young women

A single bout of prolonged, moderate-intensity endurance exercise lowers fasting and postprandial TAG concentrations the next day. However, the TAG-lowering effect of exercise is dose-dependent and does not manifest after light exercise of low energy cost ( < 2 MJ). We aimed to investigate whether superimposing mild energy intake restriction to such exercise, in order to augment total energy deficit, potentiates the hypotriacylglycerolaemic effect. Eight healthy, sedentary, premenopausal women (age 27.1 (sem 1.3) years; BMI 21.8 (sem 0.9) kg/m2) performed two oral fat tolerance tests in the morning on two different occasions: once after a single bout of light exercise (100 min at 30 % of peak oxygen consumption; net energy expenditure 1.04 (sem 0.01) MJ) coupled with mild energy intake restriction (1.39 (sem 0.22) MJ) on the preceding day, and once after resting coupled with isoenergetic feeding on the preceding day (control). Fasting plasma TAG, TAG in the TAG-rich lipoproteins (TRL-TAG) and serum insulin concentrations were 18, 34 and 30 % lower, respectively, after exercise plus diet compared with the control trial (P < 0.05). Postprandial concentrations of plasma TAG and TRL-TAG were 19 and 27 % lower after exercise plus diet compared with the control condition (P < 0.01), whereas postprandial insulin concentrations were not different. It is concluded that a combination of light exercise along with mild hypoenergetic diet may be a practical and feasible intervention to attenuate fasting and postprandial triacylglycerolaemia, especially for people who cannot exercise for prolonged periods of time at moderate-to-high intensities, such as many sedentary individuals.