Effect of alcohol on postprandial lipemia with and without preprandial exercise

OBJECTIVE: Different factors such as exercise habits and alcohol consumption may modulate postprandial lipid metabolism. What are the effects of alcohol on postprandial metabolism in untrained and trained individuals? METHODS: The postprandial lipid response to an oral fat load (1 g fat per kg body weight (bw)) with and without alcohol (0.5 g/kg bw) was evaluated in physically trained healthy young men (T, n = 12, mean +/- SD age 27 +/- 3 years. BMI 21.6 +/- 1.4 kg/m2) after a premeal running session and in untrained healthy young men (UT, n = 8, age 24 +/- 1 years, BMI 23.2 +/- 1.8 kg/m2) without a premeal exercise session. The T subjects ingested 35.5 +/- 2.7 g alcohol, the UT subjects 38 +/- 0.6 g. Fat was given as butter and the carbohydrates as marmalade and zwieback (rusk). The T subjects received 1.20 +/- 0.05 g fat and 1.02 +/- 0.04 g carbohydrates per kilogram lean body mass. The corresponding numbers for the UT subjects were 1.28 +/- 0.08 g and 1.20 +/- 0.06 g. The postprandial lipemia was observed for an eight-hour period. RESULTS: Alcohol led to an increase to the triacylglycerol area under the curve (AUC) in the T subjects from 7.4 +/- 0.4 mmol/L * h on the control day to 11.3 +/- 0.9 mmol/L * h (p = 0.001). The corresponding numbers in the UT subjects were 13.4 +/- 2.3 mmol/L * h to 19.4 +/- 3.5 mmol/L * h (p = 0.004). Alcohol intake and physical activity training were the major determinants of the triacylglycerol (TG) AUC in these subjects. CONCLUSION: The ingestion of a high fat meal in combination with alcohol leads to an increased in the postprandial lipemia independently from the level of training. It is suggested that this unfavorable effect of alcohol and a high fat diet could be modified by fat restriction or a combination of a premeal exercise session and a higher level of physical activity training.     

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.     

Multiple bouts of resistance exercise and postprandial triacylglycerol and serum C-reactive-protein concentrations

The present study examined how multiple bouts of resistance exercise, performed over 1 d, influence 2 risk factors--postprandial triacylglycerol (TAG) and serum C-reactive-protein (CRP) concentrations--associated with coronary heart disease. Twenty-four men age 23.5 (SD 3.4) y completed two 2-d trials, exercise and control, at least 1 wk apart in a counterbalanced randomized design. On day 1 of the exercise trials participants completed 20 sets of 15 repetitions of 5 different resistance exercises divided into five 45-min bouts of exercise--100 sets and 1500 repetitions in total for all exercises. Exercises were performed at 30-40% of 1-repetition maximum. Blood samples were taken before and after exercise. On day 1 of the control trial participants were inactive, with blood samples taken at time points corresponding to the exercise trial. On day 2 of both trials participants consumed a test meal (0.89 g fat, 1.23 g carbohydrate, 0.4 g protein, 60 kJ per kg body mass). Blood samples were obtained fasted and for 6 h postprandially. Total area under the postprandial TAG concentration versus time curve was 12% lower in the exercise than in the control trial (8.76 [3.54] vs. 9.94 [4.31] mmol.L(-1).6 h-1, respectively; P = 0.037). Serum CRP concentrations did not change over the 2 d in the control trial but increased in the exercise trial: trial x time interaction (P = 0.028). Multiple bouts of resistance exercise reduce postprandial TAG concentrations but increase serum CRP concentrations. The extent to which these findings are clinically relevant requires further study.     

Exchanging saturated fatty acids for (n-6) polyunsaturated fatty acids in a mixed meal may decrease postprandial lipemia and markers of inflammation and endothelial activity in overweight men

Postprandial lipemia, low-grade systemic inflammation, and endothelial activity are related to metabolic disorders. It is well known that dietary fatty acid composition modulates postprandial lipemia, but information on the other metabolic risk markers is limited. We therefore studied the acute effects of a meal rich in SFA compared with those of a meal rich in (n-6) PUFA on postprandial responses in overweight men who are at an increased risk to develop the metabolic syndrome and its comorbidities. In a crossover design, the effects of 50 g butter (rich in SFA) on lipemia and markers for inflammation and endothelial activity were compared with those of 50 g sunflower oil [rich in (n-6) PUFA] during an 8-h postprandial mixed meal tolerance test in 13 overweight men. Postprandial changes in serum TG were comparable between the meals (P = 0.38), except for a reduction in the incremental area under the curve (P = 0.046) in the late postprandial phase after (n-6) PUFA (125 ± 96 mmol?min?L(-1)) compared with SFA (148 ± 98 mmol?min?L(-1)). Compared with the SFA meal, the (n-6) PUFA meal decreased plasma IL-6 (P = 0.003), TNFα (P = 0.005), soluble TNF receptors I and II (sTNFr; P = 0.024 and P < 0.001, respectively), and soluble vascular cell adhesion molecule-1 (sVCAM-1; P = 0.030) concentrations. These results indicate that exchanging SFA from butterfat for (n-6) PUFA in a mixed meal may decrease postprandial lipemia and concentrations of IL-6, TNFα, sTNFr-I and -II, and sVCAM-1 in overweight men.     

Serum triglyceride responses to fatty meals: effects of meal fat content

To determine the dose response of serum triglyceride concentrations to fat feeding, serum triglyceride responses to meals containing 40, 80, and 120 g fat (in the form of dairy cream) were measured in 12 normotriglyceridemic men. Mean postprandial lipemia (measured as the integrated area under the curve of serum triglyceride concentration plotted against time) was 251 +/- 129 mg.dL-1.8 h-1 (2.83 +/- 1.46 mmol.L-1.8 h-1) after the 40-g-fat meal, 503 +/- 233 mg.dL-18 h-1 (5.68 +/- 2.63 mmol.L-1.8 h-1) after the 80-g-fat meal, and 712 +/- 281 mg.dL-1.8 h-1 (8.04 +/- 3.17 mmol.L-1.8 h-1) after the 120-g-fat meal. These data indicate that in normotriglyceridemic men the magnitude of lipemia that follows the ingestion of a fat meal is directly proportional to the fat content of the meal. The results also suggest that the mechanism whereby triglyceride is removed from the intravascular compartment is not saturated by meals containing the amounts of fat typically consumed by men following a Western diet.     

Whey protein ingestion enhances postprandial anabolism during short-term bed rest in young men

We tested the relative ability of rapidly digested whey and slowly digested casein to stimulate net whole-body protein synthesis during prolonged physical inactivity. We studied 8 young male volunteers after they consumed isonitrogenous casein or whey mixed meals on d 12 or d 14 of experimental bed rest. Rates of phenylalanine hydroxylation were measured by primed-constant oral administration of L[2-(2)H(2)]tyrosine and L[ring-(2)H(5)]phenylalanine for 3 h in the postabsorptive state and 6 h after an isonitrogenous bolus meal containing sucrose (0.27 g/kg) and casein or whey (0.40 g/kg). Net protein synthesis in the fed state was calculated during the first 6 h postmeal as the difference between phenylalanine hydroxylation and phenylalanine content in the ingested casein or whey. In the fed state, the integrated changes in phenylalanine hydroxylation were lower (P < 0.05) after whey (-2 +/- 8 micromol x kg(-1) x 6 h(-1)) than after casein ingestion (34 +/- 7 micromol x kg(-1) x 6 h(-1)). During bed rest, net postprandial protein synthesis was greater (P < 0.05) after whey (96 +/- 8 micromol phenylalanine x kg(-1) x 6 h(-1)) than after casein ingestion (82 +/- 7 micromol phenylalanine x kg(-1) x 6 h(-1)). The rapidly digested whey protein was more efficient than the slowly digested casein in increasing postprandial net protein synthesis during short-term bed rest.     

Exercise prevents the augmentation of postprandial lipaemia attributable to a low-fat high-carbohydrate diet

There is concern that replacement of dietary fat with carbohydrate may not reduce the overall risk of CHD because this replacement strategy elevates postprandial plasma triacylglycerol (TAG) concentrations. The present study was designed to test the hypothesis that daily exercise can offset the augmented postprandial lipaemia associated with a short-term high-carbohydrate diet. Nine healthy, normolipidaemic men aged 33 (sd 4) years consumed a test meal (g/kg body mass; 1.2 fat, 1.1 carbohydrate, 0.2 protein) on three occasions: after 3 d on a typical Western diet (46, 38 and 16 % energy from carbohydrate, fat and protein respectively); after 3 d on an isoenergetic high-carbohydrate diet (corresponding values: 70, 15 and 15 % energy); after 3 d on the same high-carbohydrate diet with 30 min moderate exercise daily. Fasting plasma TAG concentration was higher after the high-carbohydrate diet (1.15 (se 0.16) mmol/l) than after the Western diet (0.83 (se 0.10) mmol/l; ). Similarly, postprandial lipaemia (6 h total area under plasma TAG concentration v. time curve) was higher after the high-carbohydrate diet (12.54 (se 2.07) mmol/l.h) than after the Western diet (9.30 (se 1.30) mmol/l.h; ). The addition of exercise to the high-carbohydrate diet significantly reduced postprandial lipaemia (9.95 (se 1.94) mmol/l.h; when compared with the high-carbohydrate diet) but not fasting TAG concentration (1.02 (se 0.24) mmol/l). In conclusion, daily exercise prevented the augmentation of postprandial lipaemia attributable to the short-term high-carbohydrate diet and, thus, exercise may be a powerful adjunct to dietary change.     

Validity of abbreviated oral fat tolerance tests for assessing postprandial lipemia

Background & aims

Postprandial lipemia is assessed using the oral fat tolerance test (OFTT), a six-hour procedure requiring hourly blood sampling. In order to simplify the test, we investigated whether a) a single postprandial triacylglycerol concentration, b) an OFTT lasting less than six hours or c) an OFTT requiring fewer blood samples, may accurately assess postprandial lipemia under various conditions.

Methods

Seventy-two subjects underwent a conventional OFTT. Predictability of single-point concentrations and time-shortened tests was assessed using linear regression and re-sampling analysis. Validity of reduced-sampling tests was assessed using Pearson’s correlation coefficients and Bland-Altman analysis.

Results

a) A single-point triacylglycerol concentration (3 or 4 h postprandially) did not present significant correlation with postprandial lipemia in the hypetriacylglycerolemic, exercise and energy restriction groups (P > 0.05), b) Time-shortened OFTT (4 h) was able to predict postprandial lipemia in every group studied (R² = 0.707–0.970, P < 0.01), except the hypertriacylglycerolemics (P = 0.338), c) Reduced-sampling OFTT (3 or 4 samples) was able to assess postprandial lipemia in every group as well as in the overall sample (r = 0.874-0.997, P < 0.05).

Conclusions

A more convenient, reduced-sampling OFTT may be used alternatively to the conventional OFTT, whereas a time-shortened OFTT may be appropriate only for healthy people.     

Moderate exercise reduces serum triacylglycerol concentrations but does not affect pre-heparin lipoprotein lipase concentrations after a moderate-fat meal in young men

Aerobic exercise has been shown to lower postprandial TAG concentrations after a meal(s) of high-fat content. This study examined the effects of moderate-intensity cycling on postprandial TAG concentrations and pre-heparin lipoprotein lipase concentrations after subjects consumed a meal of moderate-fat content (45 % of total energy). Twelve male subjects, aged 24 (sem 1) years, completed two 2 d trials (exercise and control) at least 1 week apart in a randomised, repeated measures design. On day 1, subjects either cycled for 30 min at 65 % of maximum heart rate in the afternoon or rested (no exercise). On day 2 of both trials, after an overnight stay with an 11 h fast, subjects consumed a test meal of moderate-fat content (0.61 g fat, 1.34 g carbohydrate, 0.37 g protein and 51 kJ energy/kg body mass) for breakfast. Blood samples were collected at baseline (before the exercise or at an equivalent time-point during the control trial on day 1), in the fasted state (0 h) and at 2, 4 and 6 h postprandially on day 2. The total and incremental areas under the serum TAG concentration v. time curve were 30 % (P = 0.039) and 33 % (P = 0.012) lower on the exercise trial compared with the control trial, respectively. Serum pre-heparin lipoprotein lipase concentrations did not differ between the exercise and control trials. These findings demonstrate that 30 min of moderate-intensity cycling performed the day before a meal of moderate-fat content is effective at lowering postprandial serum TAG concentrations but does not affect serum pre-heparin lipoprotein lipase concentrations in young men.     

Effect of meal sequence on postprandial lipid, glucose and insulin responses in young men

OBJECTIVE: To investigate whether the postprandial changes in plasma triacylglycerol (TAG), nonesterified fatty acids (NEFA), glucose and insulin concentrations in young men were the same if an identical meal was fed at breakfast and lunch, and if the response to lunch was modified by consumption of breakfast. METHODS: In two trials (1 and 2) healthy subjects (age 22+/-1 y, body mass index 22+/-2 kg/m(2)) were fed the same mixed macronutrient meal at breakfast at 08:00 h and lunch at 14:00 h. In the third trial, no breakfast was fed and the overnight fast extended until lunch at 14:00 h. Addition of [1,1,1-(13)C]tripalmitin to one meal in each trial was used to distinguish between endogenous and meal-derived lipids. RESULTS: The postprandial changes in TAG, NEFA and glucose concentrations were similar in trials 1 and 2. The change in plasma total TAG concentration was about two fold less (P<0.05) after lunch compared to breakfast. Postprandial NEFA suppression was the same after breakfast and lunch. Glucose and insulin responses were significantly greater following lunch suggesting decreasing insulin sensitivity during the day. Consumption of breakfast did not alter the postprandial total TAG or NEFA responses after lunch. Measurement of [(13)C]palmitic acid concentration showed that handling of TAG and NEFA from the meal was the same after breakfast and lunch, and was not altered by consumption of breakfast. CONCLUSIONS: Overall, these data suggest that in young, healthy men regulation of plasma TAG from endogenous sources, principally VLDL, but not chylomicrons during the postprandial period leads to differences in the magnitude of lipaemic response when the same meal was consumed at breakfast or at lunch 6 h later.     

Dietary diacylglycerol in a typical meal suppresses postprandial increases in serum lipid levels compared with dietary triacylglycerol

OBJECTIVE: The objective of the present study was to verify the effect of a dietary oil, consisting mainly of diacylglycerol (DAG) oil, in a typical meal on postprandial changes in serum triacylglycerol (TAG) and remnant-like particle cholesterol (RLP-C) compared with dietary triacylglycerol (TAG) oil. METHODS: In a double-blind, randomized, crossover design, 43 healthy Japanese men and women ingested test meals (2093 kJ of energy, 30 g of protein, 19 g of lipids, and 51 g of carbohydrates) containing 10 g of DAG oil (DAG meal) or TAG oil (TAG meal). Blood samples were collected in a fasting state (0 h) and at 2, 3, 4, and 6 h after ingestion of the meal. RESULTS: Postprandial TAG, RLP-C, and chylomicron TAG concentrations were significantly lower after the DAG meal compared with the TAG meal. In 29 subjects with fasting serum TAG levels of at least 1.13 mmol/L (100 mg/dL), differences in postprandial serum changes between meal types were even more remarkable and the incremental areas under the response curve (0 to 6 h) for serum TAG and RLP-C concentrations after the DAG meal were significantly smaller than those after the TAG meal. CONCLUSIONS: These results suggest that DAG oil in the daily diet is useful for the prevention of postprandial hyperlipidemia and related disorders.     

Alcohol-mediated enhancement of postprandial lipemia: a contributing factor to an increase in plasma HDL and a decrease in risk of cardiovascular disease

BACKGROUND: Moderate alcohol consumption increases plasma HDL and lowers cardiovascular disease risk while transiently enhancing postprandial lipemia. OBJECTIVE: We hypothesized that the alcohol-mediated increase in postprandial triacylglycerol-rich lipoproteins (TRLs) and their clearance elevate HDL cholesterol and reverse cholesterol transport. DESIGN: We determined the effect in normolipidemic humans (n = 14) of postprandial lipemia produced 4 h after a test meal (M) or a test meal + 0.5 g alcohol/kg body wt (M+A) on postprandial changes in plasma lipids and on the balance of cholesterol between TRL and the cholesterol-rich LDL and HDL fractions (CRL) or red blood cells (RBCs) in fresh and incubated plasma or blood. RESULTS: Postprandial lipemia after the M and M+A test meals caused a 56% and 89% increase in plasma triacylglycerol, a 30% and 74% increase in TRL cholesterol, and a 3.8% and 6.6% decrease in CRL cholesterol, respectively. In vitro reaction of endogenous lecithin:cholesterol acyltransferase (EC 2.3.1.43) and cholesteryl ester transfer proteins via incubation of fasting plasma samples and postprandial M and M+A plasma samples for 16 h increased TRL cholesterol by 22.8% (0.08 mmol/L), 32.6% (0.16 mmol/L), and 45.8% (0.28 mmol/L) in plasma and by 71.1% (0.27 mmol/L), 89.4% (0.45 mmol/L), and 112.5% (0.70 mmol/L) in RBC-enriched blood, respectively. After the in vitro lipolysis of TRL, the elevation of HDL cholesterol in postprandial M+A plasma, but not in postprandial M plasma, was significantly greater than in fasting plasma. CONCLUSION: The alcohol-mediated increase in postprandial TRL flux and the hepatic removal of postprandial TRL after the acceptance of cholesterol from CRL and cell membranes contribute to increased HDL cholesterol and enhancement of reverse cholesterol transport in humans.     

Impaired postprandial endothelial function depends on the type of fat consumed by healthy men

Postprandial lipemia impairs endothelial function possibly via an oxidative stress mechanism. A stearic acid-rich triacylglycerol (TAG) (shea butter) results in a blunted postprandial increase in plasma TAG compared with an oleic acid-rich TAG; however, its acute effects on endothelial function and oxidative stress are unknown. A randomized crossover trial (n = 17 men) compared the effects of 50 g fat, rich in stearic acid [shea butter blend (SA)] or oleic acid [high oleic sunflower oil (HO)], on changes in endothelial function [brachial artery flow-mediated dilatation (FMD)], arterial tone [pulse wave analysis (PWA), and carotid-femoral pulse wave velocity (PWV(c-f))], and oxidative stress (plasma 8-isoprostane F2alpha) at fasting and 3 h following the test meals. The postprandial increase in plasma TAG was lower (66% lower incremental area under curve) following the SA meal [28.3 (9.7, 46.9)] than after the HO meal [83.4 (57.0, 109.8); P < 0.001] (geometric means with 95% CI, arbitary units). Following the HO meal, there was a decrease in FMD [-3.0% (-4.4, -1.6); P < 0.001] and an increase in plasma 8-isoprostane F2alpha [10.4ng/L (3.8, 16.9); P = 0.005] compared with fasting values, but no changes followed the SA meal. The changes in 8-isoprostane F2alpha and FMD differed between meals and were 14.0 ng/L (6.4, 21.6; P = 0.001) and 1.75% (0.10, 3.39; P = 0.02), respectively. The reductions in PWA and PWV c-f did not differ between meals. This study demonstrates that a stearic acid-rich fat attenuates the postprandial impairment in endothelial function compared with an oleic acid-rich fat and supports the hypothesis that postprandial lipemia impairs endothelial function via an increase in oxidative stress.     

Postprandial lipemia and chylomicron clearance in athletes and in sedentary men

To examine the effects of exercise on postprandial serum triglyceride (TG) metabolism, we measured oral and intravenous fat tolerance and chylomicron-TG half-life in highly trained endurance athletes and in a sedentary control group matched for body weight and fasting serum TG concentration. Postprandial lipemia was lower in athletes after meals containing 40 g fat (1.5 +/- 0.7 vs 2.6 +/- 1.5 mmol.L-1.8 h-1, p less than 0.001) or 140 g fat (2.5 +/- 1.2 vs 6.1 +/- 1.9 mmol.L-1.8 h-1, p less than 0.001). The disappearance of an intravenous bolus of Intralipid was faster in athletes (5.4 +/- 1.2%/min) than in sedentary men (4.3 +/- 0.8%/min, p less than 0.01). The half-life of chylomicron-TG was shorter in athletes (3.0 +/- 0.8 min) than in sedentary men (4.0 +/- 1.0 min, p less than 0.05). These findings indicate that chronic exercise decreases postprandial lipemia by reducing chylomicron-TG's half-life. This effect is due partly to reduced fasting serum TG pool size and partly to a direct effect of exercise on the serum TG removal system.     

Towards optimizing the timing of the pre-exercise meal

The purpose of this study was to compare the effect a 6-hr versus 3-hr prefeeding regimen on exercise performance. The subjects were 8 active women (21.4 +/- 0.9 years, 60.4 +/- 2.4 kg, 19.9 +/- 1.3% body fat, and 165.6 +/- 2.1 cm). All women completed 2 exercise trials (separated by 3-6 d) on a treadmill where they ran at moderate intensity for 30 min with 30-s sprints at 5-min intervals, followed directly by increasing incrementally the grade until volitional fatigue was achieved. The exercise trials were performed 3 hr and 6 hr after consuming 40 +/- 3 kJ/kg meal. Time to exhaustion was 0.75 min shorter (p =.0001) for the 6-H trials compared to the 3-H trials. There were no significant differences in submaximal or peak oxygen uptake, heart rate, or rating of perceived exertion (p >.05). The 6-H trials compared to the 3-H trials resulted in.05 lower RERs (p =.0002), and a 2 mmol lower blood lactate at exhaustion (p =.012). Blood glucose levels and cortisol responses to exercise were similar between trials (p >.05). However, both resting and post exercise insulin levels were lower during 6-H trials. It was concluded that performance of moderate- to high-intensity exercise lasting 35-40 min is improved by consuming a moderately-high carbohydrate, low fat, low protein meal 3-hr before exercise compared to a similar meal consumed 6 hr prior to exercise. Thus, athletes should not skip meals before competition or training sessions.     

The influence of low versus high carbohydrate diet on a 45-min strenuous cycling exercise

To examine the effects of a 3-day high carbohydrate (H-CHO) and low carbohydrate (L-CHO) diet on 45 min of cycling exercise, 12 endurance-trained cyclists performed a 45-min cycling exercise at 82 +/- 2% VO2peak following an overnight fast, after a 6-day diet and exercise control. The 7-day protocol was repeated under 2 randomly assigned dietary trials H-CHO and L-CHO. On days 1-3, subjects consumed a mixed diet for both trials and for days 4-6 consumed isocaloric diets that contained either 600 g or 100 g of carbohydrates, for the H-CHO and the L-CHO trials, respectively. Muscle biopsy samples, taken from the vastus lateralis prior to the beginning of the 45-min cycling test, indicated that muscle glycogen levels were significantly higher (p < .05) for the H-CHO trial (104.5 +/- 9.4 mmol/kg wet wt) when compared to the L-CHO trial (72.2 +/- 5.6 mmol/kg wet wt). Heart rate, ratings of perceived exertion, oxygen uptake, and respiratory quotient during exercise were not significantly different between the 2 trials. Serum glucose during exercise for the H-CHO trial significantly increased (p < .05) from 4.5 +/- 0.1 mmol x L(-1) (pre) to 6.7 +/- 0.6 mmol x L(-1) (post), while no changes were found for the L-CHO trial. In addition, post-exercise serum glucose was significantly greater (p < .05) for the H-CHO trial when compared to the L-CHO trial (H-CHO, 6.7 +/- 0.6 mmol x L(-1); L-CHO, 5.2 +/- 0.2 mmol x L(-1)). No significant changes were observed in serum free fatty acid, triglycerides, or insulin concentration in either trial. The findings suggest that L-CHO had no major effect on 45-min cycling exercise that was not observed with H-CHO when the total energy intake was adequate.     

Effect of Spirulina maxima on postprandial lipemia in young runners: a preliminary report

Trained people exhibit low plasma concentrations of triacylglcyerols in both fasting and postprandial states. Exercise practice is commonly believed to improve postprandial lipemia. In addition, elevated postprandial lipemia is an indicator of poor lipid clearance, and it has been associated with atherosclerosis, insulin resistance, and obesity. Spirulina maxima is an edible microorganism with a high nutritional value. When it is consumed, beneficial properties to health have been demonstrated, such as hypolipemic and antihypertensive properties in human beings. This work evaluates the effects of orally administrated S. maxima on postprandial lipemia in a young Mexican sporting population after 15 days of consumption, as a possible alternative treatment to improve their lipid clearance. Forty-one runners (10-26 years old; 21 men and 20 women) volunteered to participate in the study. All of them were physically active for at least 1 year before the study and were not undergoing training during the study. The subjects consumed 5 g of Spirulina during 15 days. Before and after the treatment with Spirulina, they consumed (12 h fasting) a standardized meal with high fat content (53.2% total calories). Postprandial lipemia was measured at 1.5, 3, and 4.5 h after the fatty meal. Fasting plasma triacylglycerol (TAG) concentrations were lower after Spirulina treatment than before treatment. In addition, the postprandial area under the curve of TAG concentrations was lower after the treatment with Spirulina. Sixty-two percent of the youngest runners (10-16 years) studied exhibited the best response to the treatment. Orally administered S. maxima decreased postprandial lipemia in sporting teenagers. The youngest people were the most responsive to the beneficial effects of Spirulina on postprandial lipemia.     

Beneficial metabolic effects of regular meal frequency on dietary thermogenesis, insulin sensitivity, and fasting lipid profiles in healthy obese women

BACKGROUND: Although a regular meal pattern is recommended for obese people, its effects on energy metabolism have not been examined. OBJECTIVE: We investigated whether a regular meal frequency affects energy intake (EI), energy expenditure, or circulating insulin, glucose, and lipid concentrations in healthy obese women. DESIGN: Ten women [x +/- SD body mass index (in kg/m(2)): 37.1 +/- 4.8] participated in a randomized crossover trial. In phase 1 (14 d), the subjects consumed their normal diet on 6 occasions/d (regular meal pattern) or followed a variable meal frequency (3-9 meals/d, irregular meal pattern). In phase 2 (14 d), the subjects followed the alternative pattern. At the start and end of each phase, a test meal was fed, and blood glucose, lipid, and insulin concentrations were determined before and for 3 h after (glucose and insulin only) the test meal. Subjects recorded their food intake on 3 d during each phase. The thermogenic response to the test meal was ascertained by indirect calorimetry. RESULTS: Regular eating was associated with lower EI (P < 0.01), greater postprandial thermogenesis (P < 0.01), and lower fasting total (4.16 compared with 4.30 mmol/L; P < 0.01) and LDL (2.46 compared with 2.60 mmol/L; P < 0.02) cholesterol. Fasting glucose and insulin values were not affected by meal pattern, but peak insulin concentrations and area under the curve of insulin responses to the test meal were lower after the regular than after the irregular meal pattern (P < 0.01 and 0.02, respectively). CONCLUSION: Regular eating has beneficial effects on fasting lipid and postprandial insulin profiles and thermogenesis.     

Postprandial effects of dietary trans fatty acids on apolipoprotein(a) and cholesteryl ester transfer

BACKGROUND: The consumption of trans fatty acids adversely affects fasting plasma lipoprotein concentrations. OBJECTIVE: This study aimed to investigate whether postprandial lipoprotein metabolism is affected by the consumption of trans fatty acids. DESIGN: In a randomized crossover study, 19 healthy men consumed fatty meals that were identical except that 10% of energy was provided as trans 18:1 acids in the trans meal and as oleic acid in the cis meal. RESULTS: The meals induced similar responses in plasma lipids. Cholesteryl ester transfer (CET) was activated after consumption of both meals (P < 0.0001); however, it was 28% higher after the trans meal than after the cis meal (280 +/- 129 compared with 219 +/- 116 nmol cholesteryl ester/mL plasma * 6 h; time x diet interaction: P < 0.0001). Plasma apolipoprotein(a) [apo(a)] concentrations remained constant; however, triacylglycerol-rich lipoproteins formed 4 h after ingestion of the trans meal contained a higher concentration of apo(a) than did those formed after ingestion of the cis meal (48.9 +/- 6.6 compared with 39.6 +/- 5.4 U/L; P < 0.02). The change in CET and in the proportion of plasma apo(a) in the triacylglycerol-rich lipoprotein fractions correlated with indexes of alimentary lipemia. CONCLUSIONS: Consumption of meals high in trans fatty acids results in higher CET and postprandial lipoprotein concentrations enriched in apo(a) than does consumption of meals free of trans fatty acids. This study highlights the importance of double-bond configuration in determining postprandial lipoprotein composition.     

Effects of low- and high-volume resistance exercise on postprandial lipaemia

Postprandial lipaemia (PL) is associated with the metabolic syndrome, CVD and endothelial dysfunction. Aerobic exercise has been shown to reduce PL. Although resistance exercise is recommended for the improvement of the quality of life, management of body weight and prevention of several disorders, its effect on PL has received little attention. The present study examined the effects of low-volume resistance exercise (LVRE) and high-volume resistance exercise (HVRE) on PL. Ten healthy young men performed three trials, each conducted over 2 d. On the afternoon of day 1, they either refrained from exercise (control), performed LVRE (two sets of eight exercises, twelve repetitions at twelve repetitions maximum (RM) in each set; energy expenditure 0 x 76 MJ), or performed HVRE (four sets of eight exercises, twelve repetitions at 12 RM in each set; energy expenditure 1 x 40 MJ). On the morning of day 2 they consumed a meal containing 67 kJ/kg body weight, of which 65 % energy was from fat. Blood samples were obtained in the fasted state and for 6 h postprandially. The total area under the TAG curve (AUC; mmol/l x h) was lower (P<0 x 05) in HVRE (8 x 76 (sd 3 x 20)) and LVRE (9 x 29 (sd 3 x 64)) compared with control (11 x 60 (sd 4 x 35)). The incremental AUC was lower in HVRE compared with control (3 x 07 (sd 2 x 53) v. 5 x 58 (sd 3 x 72)), but not different between LVRE (3 x 86 (sd 2 x 29)) and control. In conclusion, resistance exercise of 1 x 40 MJ (four sets - eight exercises - twelve RM) or 0 x 76 MJ (two sets - eight exercises - twelve RM) before a high-fat meal reduces the total postprandial lipaemic response.