A beverage of Asiatic plantain extracts alleviated postprandial oxidative stress in overweight hyperlipidemic subjects challenged with a high-fat meal: a preliminary study

There is emerging interest in the potential of the phenolic compounds of Asiatic plantain (Plantago asiatica L.) to attenuate in vitro and in vivo oxidative stress. We hypothesized that a single administration of Asiatic plantain beverage may exert protective effects against postprandial oxidative stress. This preliminary study was designed to compare the ability of different doses of Asiatic plantain beverage to mitigate the postprandial effects of a high-fat meal on the oxidation of lipids and DNA in overweight hyperlipidemic subjects. In a randomized, double-blind, placebo-controlled parallel design (n = 10/group), 40 subjects were administered a single high-fat meal with either a placebo or 1 of 3 Asiatic plantain extract beverages (low, intermediate, or high dose). Blood samples were obtained at fasting and 60, 120, 240, and 360 minutes (total of 5 samples) after intervention. The data showed a tendency for plasma free fatty acid levels to decrease in response to high-dose Asiatic plantain at all time points. Plasma oxidized low-density lipoprotein levels were significantly reduced with high-dose Asiatic plantain at 120 minutes (P = .0251 vs placebo). A comet assay revealed that DNA damage in lymphocytes was significantly decreased by Asiatic plantain at 360 minutes (P = .0225 vs placebo). There were no treatment differences in triglyceride or malondialdehyde levels. The maximum suppression was achieved with a high dose (20 g Asiatic plantain extract/80 mL). These results suggest that by protecting low-density lipoprotein and DNA, an Asiatic plantain beverage may be useful to enhance antioxidant.     

Effects of a leucine and pyridoxine-containing nutraceutical on fat oxidation, and oxidative and inflammatory stress in overweight and obese subjects

Leucine stimulates tissue protein synthesis and may also attenuate adiposity by increasing fatty acid oxidation and mitochondrial biogenesis in muscle and adipocytes. Accordingly, the effects of a nutraceutical containing 2.25 g leucine and 30 mg pyridoxine (Vitamin B6) (NuFit active blend) were tested in cell culture and in a clinical trial. 3T3L1 adipocytes were treated with leucine (0.25 mM or 0.5 mM) and/or Pyridoxal Phosphate (PLP) (50 nM or 100 nM) for 48 h. For the clinical trial, twenty overweight or obese subjects received the NuFit active blend or placebo three times/day for 4 weeks without energy restriction. Leucine decreased fatty acid synthase (FAS) expression and triglyceride content in adipocytes, and PLP addition significantly augmented this effect. Administration of NuFit active blend in the clinical trial increased fat oxidation by 33.6 g/day (p < 0.04), decreased respiratory quotient, improved HOMA(IR), reduced oxidative and inflammatory biomarkers (plasma MDA, 8-isoprostane-F(2α), TNF-α, C-reactive protein), and increased the anti-inflammatory marker adiponectin. These data indicate that the NuFit active blend significantly increased fat oxidation and insulin sensitivity, and reduced oxidative and inflammatory stress. Therefore, the NuFit active blend appears to be a useful nutraceutical in the management of obesity and associated co-morbidities.     

Effects of antioxidants on postprandial oxidative stress and endothelial dysfunction in subjects with impaired glucose tolerance and Type 2 diabetes

Aim

To compare changes in the oxidation–reduction balance and endothelial function before and after meal in patients with type 2 diabetes or impaired glucose tolerance and determine the effects of standard antioxidant supplementation.

Methods

Forty diabetics and 40 subjects with impaired glucose tolerance were compared with a control group. We assessed before and after a test meal (homogenized milkshake containing 80 g of saturated fat, amounting to 1,480 kcal), some reactive oxygen species, inflammation markers and flow-mediated vascular dilatation. These parameters were then reassessed after standard antioxidant treatment.

Results

After the meal, diabetics, subjects with impaired glucose tolerance and controls had higher levels of oxidant compounds compared to fasting levels. In subjects with diabetes and impaired glucose tolerance (IGT), Vascular Adhesion Molecule-1 and CRP were higher after the meal—diabetic subjects exhibited lower fasting flow-mediated dilatation, which deteriorated significantly after the meal. Antioxidant administration significantly improved the parameters investigated in all subjects.

Conclusions

In diabetic subjects, altered glycaemia and lipaemia are closely correlated with markers of systemic oxidative stress. Our results show that the abnormal changes in oxidative-reductive balance parameters are paralleled by similar changes in markers of endothelial dysfunction and inflammation at 4 h after ingestion of a fatty meal. Supplementation with a pool of antioxidants can reduce oxidative stress and inflammation in healthy subjects and, more importantly, in IGT patients. This previous aspect suggests that the timing of antioxidant supplementation has an important role in endothelium protection in healthy and pre-diabetic subjects, and along with prompt antioxidant treatment before irreversible endothelial damage has occurred, may have an important protective role in subjects with IGT—patients who require administration of adequate dietary antioxidants.     

Exercise and postprandial lipaemia: effects on peripheral vascular function,oxidative stress and gastrointestinal transit

Postprandial lipaemia may lead to an increase in oxidative stress, inducing endothelial dysfunction. Exercise can slow gastric emptying rates, moderating postprandial lipaemia. The purpose of this study was to determine if moderate exercise, prior to fat ingestion, influences gastrointestinal transit, lipaemia, oxidative stress and arterial wall function. Eight apparently healthy males (age 23.6 ± 2.8 yrs; height 181.4 ± 8.1 cm; weight 83.4 ± 16.2 kg; all data mean ± SD) participated in the randomised, crossover design, where (i) subjects ingested a high-fat meal alone (control), and (ii) ingested a high-fat meal, preceded by 1 h of moderate exercise. Pulse Wave Velocity (PWV) was examined at baseline, post-exercise, and in the postprandial period. Gastric emptying was measured using the¹³C-octanoic acid breath test. Measures of venous blood were obtained prior to and following exercise and at 2, 4 and 6 hours post-ingestion. PWV increased (6.5 ± 1.9 m/sec) at 2 (8.9 ± 1.7 m/sec) and 4 hrs (9.0 ± 1.6 m/sec) post-ingestion in the control group (time × group interaction, P < 0.05). PWV was increased at 2 hrs post-ingestion in the control compared to the exercise trial; 8.9 ± 1.7 vs. 6.2 ± 1.5 m/sec (time × group interaction, P < 0.05). Lipid hydroperoxides increased over time (pooled exercise and control data, P < 0.05). Serum triacylglycerols were elevated postprandially (pooled exercise and control data, P < 0.05). There were no changes in gastric emptying, cholesterol, or C-reactive protein levels. These data suggest that acute exercise prior to the consumption of a high-fat meal has the potential to reduce vascular impairments.     

Effects of diacylglycerol on postprandial energy expenditure and respiratory quotient in healthy subjects

OBJECTIVE: This study examined the effects of a diacylglycerol (DAG)-containing diet on postprandial energy expenditure and respiratory quotient. METHODS: A randomized, double-blind, crossover, placebo-controlled study with a washout period was performed in 13 healthy male subjects. A 4240-kJ diet containing 30 g of triacylglycerol (TAG) or DAG (TAG meal or DAG meal, containing 34.5% lipids, 52.1% carbohydrates, and 14.1% proteins) was administered after a fasting period of 15 to 16 h. Breath and serum were analyzed for up to 5 h after ingestion of the meal. RESULTS: The amount of change in energy expenditure 3 h after loading with the DAG meal tended to be higher than that after loading with the TAG meal (P < 0.1). Changes in respiratory quotient 2 and 5 h after loading with the DAG meal were significantly lower than those after loading with the TAG meal, suggesting high lipid oxidation activity after the meal. The serum insulin level 0.5 h after loading with the DAG meal was significantly lower than that after loading with the TAG meal. This result suggests that there is a smaller stimulus in the direction of fat storage after loading with the DAG meal. CONCLUSIONS: Compared with the TAG-containing meal, the DAG-containing meal tended to produce a higher postprandial energy expenditure and a significantly lower postprandial respiratory quotient. These results suggest that the DAG-containing meal has high postprandial lipid oxidation activity and a potential effect on high diet-induced thermogenesis.     

Effect of prior exercise on postprandial triglycerides in overweight young women after ingesting a high-carbohydrate meal

To examine the effect of prior exercise on the postprandial lipid response to a high-carbohydrate meal in normal-weight (NW=BMI <25) and overweight (OW=BMI >or= 25) women (age 18-25), 10 NW and 10 OW participants completed 2 conditions separated by 1 month. In the morning, the day after control (CT=no exercise) or exercise conditions (EX=60 min cycling at 60% VO(2peak)), participants consumed a high-carbohydrate meal (80% CHO, 15% protein, 5% fat; 75 kJ/kg BM) followed by 6 hr of hourly blood sampling. Blood was analyzed for triglycerides (TG), blood glucose (BG), and insulin (IN). TG levels over the 6-hr period were lower in NW than OW (p= .021) and lower in EX than in CT (p= .006). Area under the curve (AUC) for TG was lower in NW than OW (p= .016) and EX than CT (p= .003). There were nonsignificant tendencies for reduced BG over time (p= .053) and AUC (p= .083), and IN AUC was lower in EX than in CT (p= .040) for both groups and lower in NW than in OW (p= .039). Prior exercise improved TG levels after a high-carbohydrate meal in both groups, and OW women demonstrated a greater postprandial lipemic response than NW regardless of condition. There were tendencies for improved glucose removal with prior exercise in NW vs. OW. Acute exercise can improve postprandial TG responses and might also improve postprandial BG and IN after a large meal in NW and OW young women.     

The acute effects of psyllium on postprandial lipaemia and thermogenesis in overweight and obese men

Overweight and obesity is one of the risk factors for developing CVD. At present, very little is known about the acute effects of dietary fibre on lipids, glucose and insulin, resting energy expenditure and diet-induced thermogenesis in overweight and obese individuals. This study examined the postprandial metabolic effects of dietary fibre in overweight and obese men. Ten overweight and obese men consumed a mixed meal accompanied by either a high-fibre or low-fibre supplement on two separate visits, in a random order, 1 week apart. Two isoenergetic breakfast meals with similar composition were consumed by ten overweight/obese men. The meals contained either a low (3 g) or high (15 g) amount of fibre, low-fibre meal (LFM) and high-fibre meal (HFM) respectively. Analysis was carried out using paired t test and ANOVA. Serum TAG incremental area under the curve during 6 h of the postprandial period was significantly lower after the consumption of HFM compared with LFM. At the first hour of the postprandial period, plasma apo B48 concentration after consumption of HFM was significantly lower compared with LFM. The resting energy expenditure and diet-induced thermogenesis after both meals was similar during 6 h of the postprandial period. Collectively, these findings suggest that a single acute dose of dietary fibre in the form of psyllium supplement can decrease arterial exposure to TAG and modify chylomicron responses in the postprandial period.     

Daily intake of conjugated linoleic acid-enriched yoghurts: effects on energy metabolism and adipose tissue gene expression in healthy subjects

Conjugated linoleic acid (CLA) is a group of positional and geometric isomers of conjugated dienoic derivatives of linoleic acid. The present study was designed to determine whether 14-week CLA supplementation as triacylglycerols (3.76 g) with a 50 : 50 combination of the two main isomers (35 % cis-9, trans-11 and 35 % trans-10, cis-12) added to flavoured yoghurt-like products was able to alter body composition in healthy subjects and to alter the expression of several key adipose tissue genes (PPAR gamma, lipoprotein lipase (LPL), hormone-sensitive lipase (HSL) and uncoupling protein 2 (UCP-2)). Forty-four healthy subjects were randomly assigned to consume daily either a CLA-supplemented yoghurt-like product or a placebo yoghurt for 98 d. There were no significant effects of CLA supplementation on body weight, fat mass or free fat mass. Basal energy expenditure expressed as kg free fat mass increased significantly in the CLA group (123.3 (SEM 2.5) kJ/kg free fat mass per d on day 98 v. 118.7 (SEM 2.3) kJ/kg free fat mass per d on day 0, P = 0.03). PPAR gamma mRNA gene expression increased significantly with CLA supplementation (53 (SEM 20) %, P < 0.01) and a significant reduction in mRNA levels of HSL was observed ( - 42 (SEM 7) %, P = 0.01). The levels of UCP-2 and LPL mRNA were not affected. The present results suggest that a 98 d supplementation diet with a 50 : 50 mixture of the two CLA isomers cis-9, trans-11 and trans-10, cis-12 in a dairy product was unable to alter body composition, although a significant increase in the RMR has been induced. Moreover, changes in mRNA PPAR gamma and HSL in adipose tissue were recorded.     

Influence of moderate energy restriction and seafood consumption on bone turnover in overweight young adults

BACKGROUND: Overweight and obesity are increasing in young adults. However, moderate energy restriction aimed at lowering body weight may promote bone turnover and bone loss. Inclusion of fish or fish oils in a weight-loss diet may attenuate these adverse skeletal effects. OBJECTIVE: We examined the effects of incorporating fish or fish oil into an energy-restricted diet on bone turnover markers in young overweight adults. DESIGN: While following a strict hypoenergetic (-30% relative to estimated requirements) diet for 8 wk, 276 overweight men and women [body mass index (in kg/m(2)): 27.5-32.5; age: 20-40 y) were randomly assigned to 1 of 4 dietary groups: sunflower-oil capsules (3 g/d; control), cod (3 x 150 g/wk), salmon (3 x 150 g/wk), and fish-oil capsules (3 g/d). Body weight, bone biomarkers, and 25-hydroxyvitamin D were measured at baseline and endpoint. Data were analyzed with repeated-measures analysis of variance and general linear models. RESULTS: The mean (+/-SD) weight loss was 5.14 +/- 3.0 kg (5.8% +/- 3.2% body weight) during the 8 wk in the 4 dietary groups combined. Urinary N-telopeptides of type I collagen and serum C-terminal telopeptide of type I collagen increased (P < 0.05), whereas serum osteocalcin (but not bone-specific alkaline phosphatase) decreased (P < 0.05) from baseline to endpoint. Increased fish or fish-oil consumption had no effect (P > 0.1) on the changes in bone markers induced by weight loss. In contrast, increased salmon consumption increased serum 25-hydroxyvitamin D (P < 0.01). CONCLUSIONS: A nutritionally adequate but energy-restricted diet, with different contents of n-3 fatty acids, which resulted in modest weight loss, unfavorably altered bone turnover markers in young overweight adults. Such changes were not prevented by increased fish or fish-oil consumption.     

Natto and viscous vegetables in a Japanese-style breakfast improved insulin sensitivity, lipid metabolism and oxidative stress in overweight subjects with impaired glucose tolerance

We previously suggested that the consumption of natto and viscous vegetables as part of a Japanese-style meal based on white rice (WR) reduced postprandial glucose and insulin levels in healthy subjects. The aim of the present study was to assess whether a single breakfast of natto and viscous vegetables or the same breakfast consumed for 2 weeks could improve glucose control, insulin sensitivity, lipid metabolism and oxidative stress in overweight subjects with impaired glucose tolerance (IGT). A total of eleven free-living subjects with IGT followed a randomised, crossover breakfast intervention for 2 weeks. The test meal included boiled WR with natto (viscous fermented soyabeans), Japanese yam and okra. The control meal included WR with non-viscous boiled soyabeans, potatoes and broccoli. Both meals contained comparable amounts of carbohydrate, fat, protein and fibre. The test meal reduced acute glucose and insulin responses compared to the control meal in the study participants. Insulin sensitivity was assessed using the composite insulin sensitivity index (CISI) after both the test and control meal periods. The test meal resulted in improvements in CISI compared to the baseline, whereas no significant changes were observed after the control meal period. Serum levels of both total and LDL-cholesterol were assessed before and after the test meal period and found to decrease significantly. There was also a tendency towards reduced serum malondialdehyde-modified LDL and N(?)-carboxymethyllysine. No differences were observed in the measures of chronic glycaemic control. Thus, we conclude that a breakfast of natto and viscous vegetables consumed for 2 weeks improves insulin sensitivity, serum lipid and oxidative stress.     

海藻酸钠在生物医药领域的应用与研究进展

肥胖症是引起很多疾病的危险因素,能量摄入在肥胖发生过程中具有重要作用。研究表明饮食中增加膳食纤维的摄入量可以促进肠道蠕动,增加饱腹感,减少能量摄入。褐藻膳食纤维（alginate）是从褐藻细胞壁中提取出来的海洋纤维,其在控制膳食能量的作用及机理近来引起研究者的广泛关注。本文对褐藻膳食纤维调控能量产生、储存和消耗的影响因素和机制进行综述。     

Energy-intake restriction and diet-composition effects on energy expenditure in men

Eight men were fed at maintenance for 2 wk, followed by 4 wk at 50% of maintenance, then 1 wk at maintenance. The diets were formulated to contain either 40% or 20% of energy from fat. Daily energy expenditure (24-h EE) was determined by indirect calorimetry at the end of the 2-wk maintenance period; on days 1, 7, and 28 of reduced energy intake; and on days 1 and 7 of refeeding. During the reduced-energy period, body weight decreased from 96.6 to 91.5 kg and body fat decreased from 30.4% to 27.7%. There were no significant differences in 24-h EE or energy requirements per unit body weight due to diet composition or weight loss. Maintenance metabolizable-energy (ME) requirement averaged 31.0 kcal/kg body wt. Overall, the efficiency of ME use relative to body stores was 0.87 and was greater for high-fat than for low-fat diets. There was some evidence of an increase in the efficiency of energy use of body stores after weight loss. Substrate use reflected diet composition and energy-balance status independent of changes in body composition.     

Dietary restriction of lycopene for a period of one month resulted in significantly increased biomarkers of oxidative stress and bone resorption in postmenopausal women

Background and Objectives  

Lycopene is a carotenoid commonly found in tomatoes and tomato products which acts as an antioxidant to decrease oxidative stress and osteoporosis risk. We wanted to determine the effects of a lycopene-restricted diet on oxidative stress parameters and bone turnover markers in postmenopausal women.     

Acute effects of ingestion of black tea on postprandial platelet aggregation in human subjects

Results of population studies suggest that black tea can reduce cardiovascular risk. Effects of black-tea polyphenols to reduce platelet aggregability may help to explain any benefits. Given that black tea is often consumed with and after meals, and man spends much of his life in the postprandial state, the objective of the present study was to investigate the acute effects of ingestion of black tea on postprandial platelet aggregation ex vivo. Twenty healthy participants had platelet aggregation and blood lipids assessed before and 4 h after the ingestion of 50 g dairy fat on two occasions in random order, corresponding to black tea or hot water. Black tea or hot water (one cup) was consumed immediately following the dairy fat, then after 15 and 30 h. Platelet aggregation ex vivo was assessed in platelet-rich plasma in response to three concentrations of collagen (0.2, 0.6, 20 microg/ml) and ADP (2, 4, 8 microM). Urinary concentrations of 4-O-methylgallic acid were used as an indicator that tea polyphenols were absorbed. Serum total cholesterol and triacylglycerol concentrations increased significantly 4 h after ingesting the dairy fat, but there was no significant difference between black tea and hot-water treatments on the cholesterol or triacylglycerol responses. Urinary 4-O-methylgallic acid concentrations were significantly increased following ingestion of black tea (P=0.0001) but not water. Black tea in comparison to hot water did not inhibit collagen or ADP-induced postprandial platelet aggregation. The results of this study do not support the suggestion that reduced postprandial platelet aggregability contributes to any benefits of black tea on cardiovascular risk.     

Acute differential effects of dietary protein quality on postprandial lipemia in obese non-diabetic subjects

Non-fasting triglyceridemia is much closer associated to cardiovascular risk compared to fasting triglyceridemia. We hypothesized that there would be acute differential effects of four common dietary proteins (cod protein, whey isolate, gluten, and casein) on postprandial lipemia in obese non-diabetic subjects. To test the hypothesis we conducted a randomized, acute clinical intervention study with crossover design. We supplemented a fat rich mixed meal with one of four dietary proteins i.e. cod protein, whey protein, gluten or casein. Eleven obese non-diabetic subjects (age: 40-68, body mass index: 30.3-42.0 kg/m²) participated and blood samples were drawn in the 8-h postprandial period. Supplementation of a fat rich mixed meal with whey protein caused lower postprandial lipemia (P = .048) compared to supplementation with cod protein and gluten. This was primarily due to lower triglyceride concentration in the chylomicron rich fraction (P = .0293). Thus, we have demonstrated acute differential effects on postprandial metabolism of four dietary proteins supplemented to a fat rich mixed meal in obese non-diabetic subjects. Supplementation with whey protein caused lower postprandial lipemia compared to supplementation with cod and gluten. As postprandial lipemia is closely correlated to cardiovascular disease, long-term dietary supplementation with whey protein may prove beneficial in preventing cardiovascular disease in obese non-diabetic subjects.