三酰甘油对代谢综合征患者餐后脂代谢的影响

目的 探讨空腹TG水平对代谢综合征患者餐后脂代谢的影响.方法 将40例代谢综合征患者分为空腹TG水平升高(≥1.70 mmol/L)组(MS+HTG组,24例)和空腹TG水平正常(＜1.70 mmol/L)组(MS-HTG组,16例),同时将20例健康者作为对照组.三组受试者分别进行口服脂肪容许量测试,于餐后2、4、6、8、10 h测定TG水平,并计算其餐后TG代谢的曲线下面积(AUC).结果 MS+HTG组餐后TG的高峰水平和餐后TG代谢的AUC[(6.83±2.81)mmol/L和(26.08±16.40)mmol/(L·10 h)]均显著高于MS-HTG组[(4.12±1.14)mmol/L和(12.71±7.05)mmol/(L·10 h)]及对照组[(3.14±1.26)mmol/L和(10.28±6.09)mmol/(L·10 h)].MS+HTG组餐后TG的高峰水平较其他两组延迟2 h.MS-HTG组餐后TG的高峰水平高于对照组(P＜0.05),MS-HTG组餐后TG代谢的AUC虽高于对照组,但差异无统计学意义.相关分析结果表明,餐后TG代谢的AUC与空腹TG水平及体重指数(BMI)相关(r=0.60,P＜0.01;r=0.27,P＜0.05).多元线性回归分析结果显示,仅空腹TG水平对餐后TG代谢的AUC有预测价值(P＜0.01).结论 代谢综合征患者的空腹TG水平及BMI与餐后高TG血症独立相关.空腹TG水平对餐后高TG血症有预测价值.空腹TG水平越高,餐后TG的清除越迟缓.     

Amylose-amylopectin ratio in a meal affects postprandial variables in male volunteers.

To study the postprandial effects of changing the amylose-to-amylopectin ratio (Am:Ap) in the starch fraction of a meal, male volunteers were given hot mixed lunches (13% of energy as protein, 24% as fat, 6% as mono- and disaccharides, and 57% as polysaccharides) in which Am:Ap was either 0:100 or 45:55. The increase in Am:Ap resulted in a change in the shape of the glucose and insulin responses in the blood with significantly lower initial responses but a small increase for glucose and a decrease for insulin if averaged over the 6 h of the study. The rises in the concentration of free glycerol and free fatty acid that occurred after an initial drop were stronger at low Am:Ap. High-Am:Ap meals induced more satiety up to 6 h postprandially. There was no effect of Am:Ap on postprandial triacylglycerol in the blood or on breath hydrogen except for a weak trend toward a higher concentration at 6 h after the high-Am:Ap meals.     

Dietary carbohydrate-to-fat ratio: influence on whole-body nitrogen retention, substrate utilization, and hormone response in healthy male subjects

The effect of a high-carbohydrate and a high-fat diet on nitrogen retention, substrate utilization, and serum hormone concentrations was assessed in six healthy male subjects. Both diets were fed at a level estimated to provide maintenance and 75% maintenance energy requirements. Urine and feces were collected and analyzed for N and energy content. Anthropometric measurements; fasting and postprandial oxygen consumption; and serum levels of glucose, triglycerides, and metabolic hormones were measured. The high-fat diet increased N retention at both energy levels with significance reached at maintenance energy intakes (p less than 0.05). The high-fat diet resulted in less weight loss (p less than 0.05) at low energy and a consistently lower respiratory quotient (p less than 0.05), indicative of increased fat oxidation. The N sparing effect of the high-fat diet did not appear to be explained by hormone levels observed but may be substrate mediated.     

Low fasting low high-density lipoprotein and postprandial lipemia

Background  

Low levels of high density lipoprotein (HDL) cholesterol and disturbed postprandial lipemia are associated with coronary heart disease. In the present study, we evaluated the variation of triglyceride (TG) postprandially in respect to serum HDL cholesterol levels.     

Impact of sugar beet pectin and polydextrose on fasting and postprandial glycemia and fasting concentrations of serum total and lipoprotein lipids in middle-aged subjects with abnormal glucose metabolism

OBJECTIVE: To examine the effects of sugar beet pectin (SBP) and polydextrose (PDX) on fasting plasma glucose concentration, serum lipid profile and postprandial glycemia in middle-aged subjects with abnormal glucose metabolism. DESIGN: A placebo-controlled, randomized, parallel double-blinded study. SUBJECTS AND SETTING: Subjects were recruited via newspaper announcements. Seventy subjects were recruited of which 66 completed the study. INTERVENTION: The intervention period lasted for 12 weeks during which the subjects consumed a drink enriched with either SBP (n=22) or PDX (n=22) or without fiber enrichment (control group, n=22). The daily dose of the drinks was 4 dl. The subjects were also given nutrition counseling. Postprandial glycemia was examined in 24 subjects (n=8 in each group) at 0 and 12 weeks after a standardized breakfast. RESULTS: Fasting plasma glucose concentration did not change in the SBP and PDX groups, whereas it increased in the control group (P=0.007). On the contrary, the glycosylated hemoglobin A1(c) increased marginally but significantly (P< or =0.05) in the intervention groups without a change in the control group. In postprandial glycemia, no differences between the groups were found. In both the SBP and PDX groups, fasting serum High-density lipoprotein (HDL)-cholesterol concentration increased (P< or =0.05) without a change in the control group. Total to HDL-cholesterol ratio decreased in all groups (P< or =0.05). CONCLUSIONS: It was found that SBP and PDX do not have positive effects on fasting or postprandial plasma glucose concentrations or serum lipid profile in subjects with abnormal glucose metabolism.     

Influence of the glycaemic index of an evening meal on substrate oxidation following breakfast and during exercise the next day in healthy women

OBJECTIVE: To investigate whether the 'overnight second-meal effect' results in altered substrate oxidation during the postprandial period following breakfast and subsequent sub-maximal exercise in women. SUBJECTS/METHODS: Seven recreationally active women were recruited for the study. In each trial, participants were provided with their evening meal on day 1, which was composed of either high glycaemic index (HGI) or low glycaemic index (LGI) carbohydrates (CHO). On day 2, participants were provided with a standard HGI breakfast and then performed a 60 min run at 65% \[V.]O(2 max) 3 h later. RESULTS: The incremental area under the curve (IAUC) for plasma glucose concentrations during the postprandial period following breakfast was greater in the HGI trial compared to the LGI trial (P<0.01). Similarly, the IAUC for serum insulin concentrations was greater in the HGI trial than the LGI trial (P<0.05). No differences in plasma free-fatty acids (FFA) or plasma glycerol concentrations were found between trials during the postprandial period. During subsequent exercise, there were no significant differences in substrate metabolism. CONCLUSION: The glycaemic index of an evening meal does not alter substrate oxidation at rest following breakfast or during subsequent submaximal exercise in women. This study provides further evidence for the overnight second-meal effect on glycaemic responses following a LGI mixed evening meal.     

No effect of pre-exercise meal on substrate metabolism and time trial performance during intense endurance exercise

To determine the effect of macronutrient composition of pre-exercise meals on exercise metabolism and performance, 8 trained men exercised for 30 min above lactate threshold (30LT), followed by a 20-km time trial (TT). Approximately 3.5 h before exercise, subjects consumed a carbohydrate meal (C; 3 g carbohydrate/kg), an isoenergetic fat meal (F; 1.3 g fat/kg) or a placebo meal (P; no energy content) on 3 separate occasions in randomized order. Treatments had no effect on carbohydrate oxidation during exercise, but C decreased whole-body fat oxidation during the last 5 min of 30LT and TT, respectively (3.2 +/- 1.6 and 4.8 +/- 2.1 micromol/kg(-1) x min(-1), p < .05) when compared to F (13.3 +/- 1.6 and 16.5 +/- 2.7 micromol x kg(-1) x min(-1)) and P (15.9 +/- 2.7 and 17.0 +/- 3.2 micromol x kg(-1) x min(-1)). Glucose rate of appearance (Ra) and disappearance (Rd), and muscle glycogen utilization were not significantly different among treatments during exercise. TT performances were similar for C, F, and P (32.7 +/- 0.5 vs. 33.1 +/- 1.1 and 33.0 +/- 0.8 min, p > 0.5). We conclude that the consumption of a pre-exercise meal has minor effects on fat oxidation during high-intensity exercise, and no effect on carbohydrate oxidation or TT performance.     

Acute effects on metabolism and appetite profile of one meal difference in the lower range of meal frequency

A gorging pattern of food intake has been shown to enhance lipogenesis and increase body weight, which may be due to large fluctuations in storage and mobilisation of nutrients. In a state of energy balance, increasing meal frequency, and thereby decreasing inter-meal interval, may prevent large metabolic fluctuations. Our aim was to study the effect of the inter-meal interval by dividing energy intake over two or three meals on energy expenditure, substrate oxidation and 24 h satiety, in healthy, normal-weight women in a state of energy balance. The study was a randomised crossover design with two experimental conditions. During the two experimental conditions subjects (fourteen normal-weight women, aged 24.4 (SD 7.1) years, underwent 36 h sessions in energy balance in a respiration chamber for measurements of energy expenditure and substrate oxidation. The subjects were given two (breakfast, dinner) or three (breakfast, lunch, dinner) meals per d. We chose to omit lunch in the two meals condition, because this resulted in a marked difference in inter-meal-interval after breakfast (8.5 h v. 4 h). Eating three meals compared with two meals had no effects on 24 h energy expenditure, diet-induced thermogenesis, activity-induced energy expenditure and sleeping metabolic rate. Eating three meals compared with two meals increased 24 h fat oxidation, but decreased the amount of fat oxidised from the breakfast. The same amount of energy divided over three meals compared with over two meals increased satiety feelings over 24 h. In healthy, normal-weight women, decreasing the inter-meal interval sustains satiety, particularly during the day, and sustains fat oxidation, particularly during the night.     

The acute effects of different sources of dietary calcium on postprandial energy metabolism

Dairy Ca intake has been shown to be superior to elemental Ca in increasing the loss of body fat during energy restriction. We questioned whether the mechanisms involved an increase in postprandial energy expenditure, fat oxidation and/or a greater lipolysis. The acute effects of different sources of Ca were examined in eight subjects, aged 47-66 years and BMI 27.6-36.1 kg/m2, in a three-way cross-over study. Subjects were randomly provided breakfast meals either low in dairy Ca and vitamin D (LD; control), high in non-dairy Ca (calcium citrate) but low in vitamin D (HC) or high in dairy Ca and vitamin D (HD). Diet-induced thermogenesis, fat oxidation rates (FOR), carbohydrate oxidation rates (COR), insulin, glucose, NEFA and glycerol were measured hourly over a 6 h postprandial period. Postprandial data were calculated as a change (Delta) from the fasting value. Results showed that DeltaNEFA was significantly different between meals (LD -1.50 (sem 0.26), HC -1.22 (sem 0.32), HD -0.94 (sem 0.27) mmol/l x 6 h; P = 0.035), with a lesser suppression following both high-Ca meals. DeltaFOR was significantly higher following the two high-Ca meals (LD -6.5 (sem 2.2), HC 2.93 (sem 2.34), HD 3.3 (sem 2.5) g x 6 h; P = 0.005), while reciprocally DeltaCOR was significantly lower. DeltaGlycerol was less suppressed following the high-Ca meals but statistical significance was not achieved. No differences in diet-induced thermogenesis, insulin or glucose were observed. Regardless of source, Ca intake acutely stimulated postprandial fat oxidation; and there was a lesser suppression of NEFA following these meals.     

Influence of dietary carbohydrate-to-fat ratio on whole body nitrogen retention and body composition in adult rats

Experiments have shown that the amount and source of dietary energy may alter protein metabolism. A high fat diet has resulted in greater nitrogen retention than a high carbohydrate (CHO) diet. To examine this question further, adult rats were fed diets providing ratios of CHO:FAT as a percentage of energy of 0.5, 1.0, 1.5, 2.0, 2.5 or 3.0 for 6 wk. Mean energy and protein intakes were 93.0 +/- 0.8 kcal/d and 5.3 +/- 0.1 g/d, respectively. Final body weight was lower in rats fed the high fat diet (CHO:FAT, 0.5) than in rats fed the high carbohydrate diet (CHO:FAT, 3.0) (P less than 0.05), and a linear response was observed over the entire range of treatments (r = 0.92). Rats fed the high fat diet had the highest nitrogen balance; values were significantly (P less than 0.05) different from those of rats fed high carbohydrate diets (CHO:FAT, 2.0 or 2.5) when expressed as mg nitrogen/kcal energy gain. Rats fed the high fat diet had the highest protein gain and the lowest fat gain as a function of energy gain. It is concluded that alterations in nonprotein energy source result in metabolic changes, which may be related to adaptations in energy expenditure and/or protein deposition.     

Change in postprandial substrate oxidation after a high-fructose meal is related to body mass index in healthy men

Oral fructose decreases fat oxidation and increases carbohydrate oxidation in obese subjects, but the metabolic response to fructose in lean individuals is less well understood. The purpose of this study was to assess the effects of a single fructose-rich mixed meal on substrate oxidation in young healthy nonobese men. We hypothesized that a decrease in fat oxidation and an increase in carbohydrate oxidation would be observed after a fructose-rich mixed meal compared with a glucose-rich mixed meal. Twelve healthy, normal weight to overweight, aged 23 to 31 years participated in a double-blind, crossover study. Each participant completed 2 study visits, eating a mixed meal containing 30% of the calories from either fructose or glucose. Blood samples for glucose, insulin, triglycerides, and leptin as well as gas exchange by indirect calorimetry were measured intermittently for 7 hours. Serum insulin was higher after a fructose mixed meal, but plasma glucose, plasma leptin, and serum triglycerides were not different. Mean postprandial respiratory quotient and estimated fat oxidation did not differ between the fructose and glucose meals. The change in fat oxidation between the fructose- and glucose-rich meals negatively correlated with body mass index (BMI; r = −0.59 [P = .04] and r = −0.59 [P = .04] at the 4- and 7-hour time points, respectively). In healthy nonobese men, BMI correlates with altered postprandial fat oxidation after a high-fructose mixed meal. The metabolic response to a high-fructose meal may be modulated by BMI.     

Variation in the effects of three different breakfast meals on subjective satiety and subsequent intake of energy at lunch and evening meal

Purpose

To determine the relative impact of three iso-caloric breakfast meals, of variable composition, on satiety, hunger and subsequent intake of energy.

Methods

In a three-way, crossover design, 30 healthy men (age of 21.7 ± 1.2 years; BMI, 23.1 ± 2.7 kg/m²) were randomised to one of three test breakfasts, on three separate occasions, separated by 1 week. The breakfasts consisted of eggs on toast, cereal (cornflakes) with milk and toast, or a croissant and orange juice. Subjective ratings of satiety, hunger, fullness and desire to eat were recorded at 30-min intervals by electronic visual analogue scales (VAS). Energy intake was assessed by weighed food intake at an ad libitum lunch and evening meal.

Results

Participants showed increased satiety, less hunger and a lower desire to eat after the breakfast containing eggs relative to the cereal (p < 0.02), and croissant-based meals (p < 0.0001). The egg breakfast was also accompanied by a significantly lower intake of energy relative to the croissant- and cereal-based breakfasts at the buffet lunch and evening meal, respectively, 1,284 ± 464 (egg) versus 1,442 ± 426 kcal (croissant), p = 0.03, 1,407 ± 379 (cereal) at lunch and 1,899 ± 729 (egg) versus 2,214 ± 620 kcal (cereal), p = 0.02, 2,047 ± 712 (croissant) at evening meal. The breakfast meal with the greatest effect on satiety and subsequent intake of energy was distinct in having the highest protein and lowest carbohydrate content relative to the other two breakfasts.

Conclusion

These findings provide evidence to support the importance of food choice at breakfast as a means of increasing satiety in the morning and reducing energy intake at lunch.     

The acute effects of olive oil v. cream on postprandial thermogenesis and substrate oxidation in postmenopausal women

The influence of the source of dietary fat on postprandial thermogenesis and substrate oxidation rates, was examined in twelve postmenopausal women aged 57-73 years, with BMI 21.9-38.3 kg/m(2). A single blind, randomised, paired comparison of two high-fat, isoenergetic, mixed test meals was conducted. The major source of fat was either cream (CREAM) or extra virgin olive oil (EVOO). RMR, diet-induced thermogenesis (DIT) and substrate oxidation rates over 5 h were measured by indirect calorimetry. There were no differences in body weight, RMR, fasting carbohydrate or fat oxidation rates between the two occasions. DIT (EVOO 97 (SD 46) v. CREAM 76 (SD 69) kJ/5 h and EVOO 5.2 (SD 2.5) v. CREAM 4.1 (SD 3.7)% energy) did not differ between the two test meals. The postprandial increase in carbohydrate oxidation rates, relative to their respective fasting values (DeltaCOX), was significantly lower following the EVOO meal (EVOO 10.6 (SD 8.3) v. CREAM 17.5 (SD 10) g/5 h; paired t test, P=0.023), while postprandial fat oxidation rates (DeltaFOX) were significantly higher (EVOO 0.0 (SD 4.4) v. CREAM -3.6 (sd 4.0) g/5 h; P=0.028). In the eight obese subjects, however, DIT was significantly higher following the EVOO meal (EVOO 5.1 (SD 2.0) v. CREAM 2.5 (sd 2.9) %; P=0.01). This was accompanied by a significantly lower DeltaCOX (EVOO 10.9 (SD 9.9) v. CREAM 17.3 (SD 10.5) g/5 h; P=0.03) and significantly higher DeltaFOX (EVOO 0.11 (SD 4.4) v. CREAM -4.1 (SD 4.5) g/5 h, P=0.034). The present study showed that olive oil significantly promoted postprandial fat oxidation and stimulated DIT in abdominally obese postmenopausal women.     

Perceptions of meal convenience: the case of at-home evening meals

Perceptions of a range of evening meal situations eaten in the home were explored in a female consumer population. The investigation was carried out using the repertory grid technique and using written scenarios as the research stimuli. The nine scenarios successfully manipulated perceived convenience, time and effort. A consumer-generated vocabulary pertaining to food-related convenience was derived and revealed that while elements of both time and effort contributed to perceived convenience, these two 'dimensions' were highly interdependent. The presence of terms related to planning, shopping, preparation, cooking and clean-up illustrated that all stages in the food provisioning process influenced perceived convenience. Some evidence was established of perceptual differences between individuals varying with respect to convenience orientation in meal preparation.     

Effects of alcohol and the evening meal on shear-induced platelet aggregation and urinary excretion of prostanoids

Moderate regular alcohol intake has been found to be associated with a decreased risk for coronary heart disease and stroke. We investigated the effects of acute intake of red wine (60 g ethanol) and a standard dinner under controlled conditions on haemostatic factors. Shear-induced platelet aggregation (SIPA) decreased after the intake of alcohol irrespective of whether the subjects were fasting or not, and also after the intake of food. The intake of alcohol inhibited the postprandial increase of von Willebrand factor multimers. Plasma levels of plasminogen activator inhibitor 1 activity (PAI-1) and serum triglycerides were increased by alcohol. Excretion of the platelet thromboxane A(2) metabolites 11-dehydrothromboxane B(2) and 2,3-dinorthromboxane B(2), as well as the endothelial prostacyclin metabolite 2, 3-dinor-6-ketoprostaglandin F(1)alpha, into urine was not influenced by either alcohol or food. We conclude that eating a dinner together with red wine has no untoward effect on SIPA and that the decrease of SIPA is not specific for alcohol.     

Effects of kappa opiate agonists, cholecystokinin and bombesin on intake of diets varying in carbohydrate-to-fat ratio in rats

Effects of the dietary carbohydrate-to-fat ratio on opiate-stimulated eating and on naloxone-, cholecystokinin- and bombesin-suppressed eating were examined. Rats were fed either a high carbohydrate (cornstarch) diet (68% of energy from carbohydrate and 12% from fat), an intermediate diet (40% carbohydrate and 40% fat) or a high fat (corn oil and lard) diet (3% carbohydrate and 77% fat). Other rats self-selected from the high carbohydrate and high fat diets. Subcutaneous administration of naloxone, an opiate antagonist, generally suppressed intake of the high fat diet to a greater extent than intake of the high carbohydrate diet. Neither cholecystokinin octapeptide nor bombesin (administered intraperitoneally) exerted preferential suppression of fat intake. The opiate agonists ketocyclazocine and butorphanol tartrate administered subcutaneously at 1000 h preferentially, although not exclusively, stimulated intake of the high fat diet in a dose-dependent manner during the 6-h feeding trial. Repeated daily subcutaneous injections of butorphanol tartrate caused rats to consume more than 50% of their daily intake during the 6-h period postinjection; intake during the normal night feeding period was suppressed to maintain total daily intake equal to that of vehicle-injected rats. We conclude that stimulation of the opioid feeding system contributes to the overeating often associated with consumption of a high fat diet.     

Pea fiber lowers fasting and postprandial blood triglyceride concentrations in humans

The effect of a pea cell wall fiber preparation with a high content of soluble fiber on fasting and postprandial blood lipids was investigated in young healthy subjects. Inclusion of 33 g pea fiber product/10 MJ (20 g dietary fiber) in a low fiber diet was tested in five men and six women (mean age 23 y) in a strictly controlled randomized cross-over intervention study over 2 wk separated by a 2-wk period of habitual diet consumption. No significant differences in fasting concentrations of total cholesterol, LDL cholesterol or HDL cholesterol were observed, whereas total and VLDL triglyceride concentrations were lower when subjects consumed the pea fiber diet compared with the low fiber diet (P < 0.05). Postprandial response to pea fiber was studied in eight men. Addition of 12 g pea fiber product/ 10 MJ to a breakfast meal and 15 g/10 MJ to the following lunch meal resulted in significantly lower total triglyceride (P = 0.01), chylomicron triglyceride (P = 0.03) and insulin (P = 0.003) concentrations after the lunch meal compared with results following the same meal without pea fiber. No differences were observed in glycemic response. In conclusion, this source of dietary fiber lowered fasting and postprandial triglyceride concentrations but did not change fasting cholesterol concentrations.