Effects of medium-chain and long-chain triacylglycerols in pediatric surgical patients

Medium-chain triacylglycerols (MCTs) have been shown to provide better nutritional support than long-chain triacylglycerols (LCTs). This study compares the efficacy of MCT combined with LCT with LCT alone in pediatric patients with surgical stress. Two groups of patients (n = 19 in each) received equivalent amounts of glucose (12 g. kg. d) and amino acids (2 g. kg. d), but one group received 10% Lipofundin MCT/LCT and the other received 10% LCT (1.5 g. kg. d) in a randomized study. Total parenteral nutrition (TPN) was given for 14 d. Blood and urine samples were collected before and after TPN administration for determination of various biochemical parameters. Indirect calorimetry was also performed to determine respiratory quotients and fuel utilization. After 14 d of TPN in the MCT/LCT group, there was a significantly higher blood lymphocyte percentage, a decreasing tendency of serum asparate aminotransferase and of total and direct bilirubin (P < 0.05). These changes were not observed in the LCT group. A significantly better nitrogen balance and a higher ketogenesis from day 3 were observed in the MCT/LCT group. The MCT/LCT group showed a more marked increased utilization of fat than the LCT group, whereas carbohydrate oxidation was less in the MCT/LCT group than in the LCT group (P < 0.05). In children after surgery, MCT/LCT is more protein sparing and induces a better immune response when compared with LCT-containing lipid emulsion. A TPN regimen containing MCT/LCT is likely to result in rapid oxidation of fats for energy without compromising the respiratory system.     

Effects of medium-chain triglyceride in parenteral nutrition on rats undergoing gastrectomy

This study was designed to investigate the effects of pre-infusion with total parenteral nutrition (TPN) using medium-chain triglyceride (MCT) versus long-chain triglyceride (LCT) emulsion as fat sources on hepatic lipids, inflammatory mediators and antioxidant capacity in rats undergoing gastrectomy. Rats with internal jugular catheter, were divided into two groups and received TPN. TPN supplied 300 kcal/kg/d with 39% of the energy provided as fat. All TPN solutions were isonitrogenous and identical in nutrient composition except for the fat emulsion, which was composed of MCT/LCT (1 : 1) or LCT. After receiving TPN for 5 days, the rats underwent partial gastrectomy and were sacrificed 24 h after surgery. The results of the study demonstrated that the MCL/LCT group had lower hepatic lipids than did the LCT group. No differences in interleukin-1beta, interleukin-6 and tumor necrosis factor-alpha in peritoneal lavage fluid were observed between the two groups. Erythrocyte glutathione peroxidase activity was significantly higher in the LCT group than the MCT/LCT group, although erythrocyte superoxide dismutase activity did not differ significantly between the two groups. These results suggest that infusion with MCT/LCT before an abdominal operation did not have an effect on modulating the production of inflammatory mediators in the location of the injurious stimulus. However, pre-infusion with MCT/LCT have beneficial effect in improving liver lipid metabolism and reducing oxidative stress in rats with gastrectomy.     

Studies on the tolerance of medium chain triglycerides in dogs

Two groups of five conscious dogs received total parenteral nutrition (about 100 kcal/kg body weight per 24 hr) continuously for 96 hr (0.28 g triglycerides/kg body weight per hr, constituting more than 55% of the energy supply). The only difference between the two groups was the nature of the 20% lipid emulsion. In one group, this emulsion contained only long-chain triglycerides (LCTs), and in the other it contained a mixture (vol/vol) of medium chain triglycerides (MCTs) and LCTs. MCTs thus were given in an amount of about 30% of the total energy supplied. During infusion with the MCT/LCT mixture, C8, C10, and C12 fatty acids appeared in the total plasma fatty acids. When the infusion was stopped, the medium-chain fatty acids disappeared; those with shorter chains did so more rapidly. The plasma triglyceride clearance was faster for the MCT/LCT mixture than for the LCTs, whereas phospholipid and cholesterol clearance seemed slower for the MCT/LCT mixture. With this mixture, there was a slight increase in the plasma concentrations of ketone bodies, lactate, and pyruvate, and a slight decrease in plasma glucose. The MCT/LCT mixture was well tolerated, causing no discernible problems, and, in particular, no signs of narcosis or encephalopathy.     

含中链甘油三脂的脂肪乳剂有利于胃切除术后大鼠的脂类代谢和抗氧化能力

研究胃切除大鼠于术前接受以中链甘油三酯或长链甘油三酯为脂肪来源的肠外营养对肝内脂类，炎性介质和抗氧化能力的影响。大鼠经颈内静脉插管，分成两组接受肠外营养治疗。肠外营养的能量为30kcal/kg/d， 脂肪占能量的39％。除了脂肪乳剂外所有肠外营养制剂都是等氮的并含有相同的营养成分，脂肪乳剂的成分中链／长链（1：1）或长链脂肪乳剂。大鼠于接受肠外营养5天后经部分胃切除术，于术后24小时处死。研究结果显示，中逻／长链组肝内脂肪少于长链组。提示中链／长链脂肪乳剂能改善肝脏脂类代谢。两组大鼠的腹腔灌洗液（PLF）和血液中白介素－1β（Ⅱ-1β），白介素－6（Ⅱ－6）和肿瘤坏死因子α（TNF－α）无显差别，说明术前输入中链／长链脂肪乳剂对调节大鼠循环血液中的炎性介质和手术刺激没有影响。长链脂肪乳剂组的红细胞谷胱甘肽超氧化物酶（GSHPx)的活力明显高于输入中链／长链脂肪乳剂组，但红细胞超氧化物歧化酶（SOD）的活力在两组之间无显性差别。这些结果说明，腹部手术前输入中链／长链脂肪乳剂能改善脂类代谢和减少氧化物的刺激。结论：推荐对准备行胃手术的肠外营养支持的病人使用中链／长链脂肪乳剂。     

Feeding behavior in neonates whose diet contained medium-chain triacylglycerols: short-term effects on thermoregulation and sleep

BACKGROUND: Feeding formulas for premature infants often contain medium-chain triacylglycerols (MCTs). However, previous studies in animals and adults showed that MCTs may decrease food intake. OBJECTIVES: The objectives were to determine in hospitalized premature infants whether food intake is modified by dietary MCT supply and to assess the effects on thermoregulation and sleep, which are involved in the regulation of energy metabolism and in the optimal physiologic development of the neonates. DESIGN: Food intake, body mass, and nutritional efficiency during 3 consecutive days were compared in 2 groups of neonates according to the fat composition of their feeding formula [MCT group: 37% MCT, 63% long-chain triacylglycerols (LCTs); LCT group: 100% LCT]. On the third day, sleep and metabolic rate were recorded in the morning during an interval between meals. RESULTS: Regardless of day, energy intake was greater in the MCT group than in the LCT group (x difference: 67.3 kJ x kg(-1) x d(-1); P = 0.007). Metabolic rate (1.8 mL x min(-1) x kg(-1); P < 0.001), cheek skin temperature (0.31 degrees C; P = 0.04), and total sleep time (52 min; P = 0.01) were also higher in the MCT group. CONCLUSION: The ratio of MCTs to LCTs in neonates' feeding formulas can modify physiologic functions involved in energy-balance regulation.     

Short-term effects of parenteral nutrition of cholestatic infants with lipid emulsions based on medium-chain and long-chain triacylglycerols

OBJECTIVE: Infants with chronic cholestasis may require parenteral nutrition with lipid emulsions to provide energy and essential fatty acids but the optimal strategy is controversial. METHODS: We studied the effects of parenteral lipid emulsions with long-chain triacylglycerols (LCTs) or a mixture of LCTs and medium-chain triacylglycerols (MCTs/LCTs) on serum bilirubin and lipid metabolism in cholestatic infants who received these 20% emulsions in alternating order for 3 d each, together with a glucose and amino acid infusion. RESULTS: Of 11 recruited infants, two dropped out because enteral feeding could be established. In nine infants (2-8 mo of age, mean age 4.2 mo) who completed the study, serum bilirubin decreased from baseline to 6 h after the end of LCT infusion (from 8.5 +/- 2.0 to 7.8 +/- 1.8 mg/dL, mean +/- SEM, P < 0.05) and MCT/LCT infusion (7.9 +/- 6.5 to 7.1 +/- 6.5 mg/dL, P < 0.05). Cholesterol, triacylglycerol, and phospholipid concentrations in plasma and in chylomicrons, very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein were not changed by either emulsion. Total polyunsaturated fatty acid contents in high-density lipoprotein phospholipids increased during LCT infusion (from 29.8 +/- 0.9 to 35.9 +/- 1.4% wt/wt, P < 0.05) and MCT/LCT infusion (from 30.4 +/- 1.0 to 33.0 +/- 0.7%, P < 0.05). The long-chain polyunsaturated fatty acid docosahexaenoic acid increased only with the LCT infusion. Because docosahexaenoic acid availability during infancy is important for early visual and cognitive development, the use of soybean oil-based lipid emulsions may be preferable for infants with severe progressive cholestasis. CONCLUSION: The MCT/LCT and LCT emulsions showed a good metabolic tolerance in infants with chronic cholestasis but had a differential effect on high-density lipoprotein phospholipid contents of arachidonic and docosahexaenoic acids.     

Human leukocyte death after a preoperative infusion of medium/long-chain triglyceride and fish oil parenteral emulsions: a randomized study in gastrointestinal cancer patients

Background: Parenteral lipid emulsions (LEs) can influence leukocyte functions. The authors investigated the effect of 2 LEs on leukocyte death in surgical patients with gastrointestinal cancer. Material and Methods: Twenty-five patients from a randomized, double-blind clinical trial (ID: NCT01218841) were randomly included to evaluate leukocyte death after 3 days of preoperative infusion (0.2 g fat/kg/d) of an LE composed equally of medium/long-chain triglycerides and soybean oil (MCTs/LCTs) or pure fish oil (FO). Blood samples were collected before (t0) and after LE infusion (t1) and on the third postoperative day (t2). Results: After LE infusion (t1 vs t0), MCTs/LCTs did not influence cell death; FO slightly increased the proportion of necrotic lymphocytes (5%). At the postoperative period (t2 vs t0), MCTs/LCTs tripled the proportion of apoptotic lymphocytes; FO maintained the slightly increased proportion of necrotic lymphocytes (7%) and reduced the percentage of apoptotic lymphocytes by 74%. In the postoperative period, MCT/LCT emulsion increased the proportion of apoptotic neutrophils, and FO emulsion did not change any parameter of apoptosis in the neutrophil population. There were no differences in lymphocyte or neutrophil death when MCT/LCT and FO treatments were compared during either preoperative or postoperative periods. MCT/LCTs altered the expression of 12 of 108 genes related to cell death, with both pro- and antiapoptotic effects; FO modulated the expression of 7 genes, demonstrating an antiapoptotic effect. Conclusion: In patients with gastrointestinal cancer, preoperative MCT/LCT infusion was associated with postoperative lymphocyte and neutrophil apoptosis. FO has a protective effect on postoperative lymphocyte apoptosis.     

Effect of structured lipids as energy substrate after hepatectomy in rats with streptozocin-induced diabetes.

The suitability of energy substrates for use by the remnant liver after 70% hepatectomy was studied in relation to the hepatic energy status in diabetic rats. Rats with streptozocin-induced diabetes underwent 70% hepatectomy and were divided into five groups receiving total parenteral nutrition (TPN) for 24 h. One group received standard TPN without fat, and four groups respectively received standard TPN with long-chain triglycerides (LCTs), medium-chain triglycerides (MCTs), mixed triglycerides (MIX), or structured lipids (SLs) as a 10% lipid emulsion. The latter groups received 60% of nonprotein calories per day with fat emulsion (LCT, MCT, MIX, or SL), and the remaining 40% with glucose. The group that received 100% of nonprotein calories per day with glucose was defined as the TPN group. All rats in the TPN group died from nonketotic hyperosmolarity within 24 h. The blood ketone body ratio (acetoacetate/beta-hydroxybutyrate), the energy charge level of the remnant liver, and the cumulative excretion of 14CO2 in expired breath during 6 h after [14C]glucose administration were all significantly higher in the SL group than in the other groups 24 h after hepatectomy. These findings suggest that SL may be a superior energy substrate to other triglyceride preparations during the immediate posthepatectomy phase in diabetic patients.     

Leucine metabolism in preterm infants receiving parenteral nutrition with medium-chain compared with long-chain triacylglycerol emulsions

BACKGROUND: Although medium-chain triacylglycerols (MCTs) may be utilized more efficiently than long-chain triacylglycerols (LCTs), their effect on protein metabolism remains controversial. OBJECTIVE: The aim of the study was to compare the effects of mixed MCT-LCT and pure LCT emulsions on leucine metabolism in preterm infants. DESIGN: Fourteen preterm [gestational age: 30+/-1 wk; birth weight: 1409+/-78 g (x +/- SE)] neonates were randomly assigned to receive, from the first day of life, either a 50:50 MCT-LCT (mixed MCT group; n = 7) or an LCT (LCT group; n = 7) lipid emulsion as part of an isonitrogenous, isoenergetic total parenteral nutrition program. On the fourth day, infants received intravenous feeding providing 3 g lipid, 15 g glucose, and 3 g amino acids kg(-1) x d(-1) and underwent 1) indirect calorimetry and 2) a primed, 2-h infusion of H13CO3Na to assess the recovery of 13C in breath, immediately followed by 3) a 3-h infusion of L-[1-13C]leucine. RESULTS: The respiratory quotient tended to be slightly but not significantly higher in the mixed MCT than in the LCT group (0.96+/-0.06 compared with 0.93+/-0.03). We did not detect a significant difference between the mixed MCT and LCT groups with regard to release of leucine from protein breakdown (B; 309+/-40 compared with 257+/-46 micromol x kg(-1) x h(-1)) and nonoxidative leucine disposal (NOLD; 296+/-36 compared with 285+/-49 micromol x kg(-1) x h(-1)). In contrast, leucine oxidation was greater in the mixed MCT than in the LCT group (113+/-10 compared with 67+/-10 micromol x kg(-1) x h(-1); P = 0.007). Net leucine balance (NOLD - B) was less positive in the mixed MCT than in the LCT group (-14+/-9 compared with 28+/-10 micromol x kg(-1) x h(-1); P = 0.011). CONCLUSION: Mixed MCTs may not be as effective as LCT-containing emulsions in promoting protein accretion in parenterally fed preterm neonates.     

结构脂肪乳在造血干细胞移植中应用的安全性观察

目的:观察和比较结构脂肪乳(STG)和中/长链脂肪乳(MCT/LCT)的临床不良反应,以减少肠外营养(PN)并发症的发生。方法:将32例行异基因外周造血干细胞移植的血液系统肿瘤病人分为MCT/LCT组和STG组,每组各16例。分别观察病人不良反应(恶心、呕吐、头痛、发热、胸闷、心悸)和血清总胆红素(TBil)、谷丙转氨酶(ALT)、谷草转氨酶(AST)、碱性磷酸酶(ALP)、γ-谷氨酰转肽酶(γ-GT)、清蛋白(ALB)、肌酐(Cr)和尿素氮(UN)等指标。结果:两组病人的临床不良反应无显著性差异(P0.05)。MCT/LCT组和STG组TBil异常例数分别为2例和1例;ALT、AST异常例数分别为1例和0例。两组ALP、GGT、ALB、Cr和UN均无异常。两组病人均无肝静脉闭塞病和心脏毒性改变。结论:两种脂肪乳制剂在造血干细胞移植病人的PN治疗中安全有效,不良反应小。     

Clinical and metabolic effects of two lipid emulsions on the parenteral nutrition of septic patients

OBJECTIVE: We compared the metabolic and clinical effects of two lipid emulsions, long-chain triacylglycerols (LCT) and a mixture of medium- and long-chain triacylglycerols (MCT/LCT), in septic patients. METHODS: Both groups received total parenteral nutrition (TPN) with a solution enriched with branched-chain amino acids (BCAA). Seventy-two septic patients received TPN with MCT/LCT (group 1) or LCT (group 2). Before starting TPN (basal) and 10 d after (final), various parameters were evaluated. RESULTS: Twenty-six subjects in each group completed the study. Both groups showed an increase in cholestasis enzymes, with no significant changes in lipid parameters. The rise of retinol-binding protein and the recovery of nitrogen balance were significantly greater in group 1. A multivariate analysis of nutritional markers and catabolic parameters showed a better evolution in group 1 (P = 0.002). The MCT/LCT group exhibited a significant increase of insulin levels. Overall mortality and length of stay in the intensive care unit were not affected by the lipid emulsion. CONCLUSIONS: In septic patients who received TPN with a solution enriched with BCAAs, the use of an emulsion containing MCT provided them with a greater recovery of their nutrition status than the traditional LCT formula, without influencing the outcome.     

Medium- and long-chain triacylglycerols in postoperative patients: structured lipids versus a physical mixture.

Forty patients, scheduled for abdominal surgery, were randomized to receive postoperatively either a structured or a physical mixture of long-chain triacylglycerols/medium-chain triacylglycerols (LCT/MCT) emulsions to assess the tolerance and the effectiveness of the structured triacylglycerol emulsion. Total parenteral nutrition started the day after surgery and covered 100% of measured energy expenditure with nitrogen (0.2 g N.kg-1.d-1) and non-protein calories: glucose (50%) and lipids (50%). Blood samples for liver function tests, albumin, transthyretin, and triacylglycerols were checked at 0800 h on the day before surgery and on day 1, day 3, and day 6 after surgery. Urine samples were taken each day from day 1 to day 7 for 3-methylhistidine (3 Me His) and total nitrogen measurements. Aspartate transaminase (ASAT), alanine transaminase (ALAT), and triacylglycerol plasma levels in routine clinical biochemistry increased significantly in the physical mixture group. Nitrogen balance and 3 Me His excretion were not significantly different between groups. Structured triacylglycerol (STG) lipid emulsions are as efficacious as the physical mixture on nitrogen balance in postoperative patients. They could have some advantages: no disturbances were found to occur in liver function tests or plasma triacylglycerol levels.     

Competitive effects of long-chain-triglyceride emulsion on the metabolism of medium-chain-triglyceride emulsions

This study was conducted to assess the potential metabolic competitive interactions of intravenous medium-chain-triglyceride (MCT) and long-chain-triglyceride (LCT) lipid emulsions. To assess this competition increasing concentrations of LCT emulsion were added to an intravenous dose of MCT emulsion of 3.0 g/kg body wt up to a maximum dose of 3.0 g LCTs/kg body wt. Blood samples were assessed for competitive interactions by analyzing the following metabolites: glucose, insulin, lactate, pyruvate, ketones (acetoacetate, beta-hydroxybutyrate), elimination of triglycerides, and free fatty acids. Evaluation of the data showed a strong competitive interaction between the MCT and LCT emulsions. This competition was evident as soon as LCTs were added to the MCT infusions and appeared to favor LCTs for removal and metabolism over MCTs. This appears to indicate that there is a peripheral, strong affinity site for LCT removal and metabolism and a shared peripheral site and specific visceral site for MCT removal and metabolism.     

Dietary fat level as determinant of protein-sparing actions of structured triglycerides.

This study assessed the effects of total parenteral nutrition (TPN) containing long-chain triglycerides (LCTs), an equimolar physical mixture of LCT and medium-chain triglycerides (MCTs), and a structured triglyceride synthesized from equimolar amounts of MCT and LCT on energy and protein metabolism after thermal injury (25% body surface area full-thickness scald burn). Male Sprague-Dawley rats (245-271 g) received isovolemic diets intravenously that supplied 250 kcal.kg-1.day-1, 2 g amino acid nitrogen.kg-1.day-1, and 50% of nonprotein calories as lipid and 50% as dextrose for 3 days. Whole-body and tissue leucine kinetics were estimated by a 4-h continuous infusion of L-[1-14C]leucine on day 3. Nitrogen balance, plasma albumin, plasma glucose, energy expenditure, and whole-body and liver and rectus muscle protein kinetic parameters were determined. No significant differences were noted in any of the parameters measured. This study suggests that the unique protein-sparing actions usually associated with structured triglyceride administration are not seen when they are provided as 50% of nonprotein calories. In addition, the ratio of MCT to LCT in the starting mixture from which the structured triglycerides are synthesized may be an important determinant of the protein-sparing actions attributed to these lipids.     

Effect of various lipid emulsions on total parenteral nutrition-induced hepatosteatosis in rats

The effect of various lipid emulsions on the development of fatty liver during total parenteral nutrition (TPN) was investigated in rats given TPN for 7 days. Medium-chain triglycerides (MCT), long-chain triglycerides (LCT), chemically defined triglycerides (CDT; structured lipid with a high purity of 94.3%), and a mixture of MCT and LCT (MIX) were prepared as the lipid emulsions. TPN provided 350 kcal/kg/day, with a nonprotein calorie/nitrogen ratio of 160. The TPN-1 group received 10% nonprotein calories and the TPN-2 group received 30% nonprotein calories. MCT TPN was found to have some disadvantages, especially with regard to nitrogen balance and plasma albumin levels. Total cholesterol and phospholipids tended to be high in the MCT TPN group. The hepatic lipid content was higher in the lipid-free TPN and the MCT TPN groups, and lower in the CDT and LCT TPN groups. Histologically, the livers of the MIX, CDT, and LCT TPN groups showed less fatty change than those of the FREE and MCT groups.     

MCT/LCT emulsion ameliorate liver fat deposition in insulin-treated diabetic rats receiving total parenteral nutrition

This study was designed to investigate the effects of high energy infusion and insulin treatment on plasma and liver lipids in diabetic rats receiving total parenteral nutrition (TPN). Diabetes was induced in rats by streptozotocin. The diabetic rats were assigned to two TPN groups to receive either long chain triglyceride (LCT) or medium chain triglyceride (MCT)/LCT (1:1) as a fat source. The TPN solutions were isonitrogenous, isocaloric and identical in nutrient composition except for the fat emulsion. All rats received the TPN solution at an energy level of 35|kcal/100|g of body weight. The LCT and MCT/LCT groups were further divided into two subgroups, depending on whether they were treated with insulin. The results demonstrated that, between the MCT/LCT and LCT groups, no differences were observed in body weight and nitrogen retention, as well as the concentrations of plasma glucose, nonesterified fatty acids, beta-hydroxybutyrate, and total cholesterol. Diabetic TPN rats without insulin treatment had weight loss and negative nitrogen balance during the experiment. Diabetic TPN rats treated with insulin, however, demonstrated less weight loss and positive nitrogen retention. Insulin treated groups had significantly higher liver fat content than did those without insulin treatment. Furthermore, liver fat content was significantly higher in the LCT group than in the MCT/LCT group among insulin treated TPN rats. These results suggest that compared with the LCT emulsion, infusion of the MCT/LCT emulsion ameliorated liver fat deposition in insulin-treated diabetic rats receiving TPN.     

结构脂肪乳剂与物理混合的中/长链脂肪乳剂脂肪酸代谢比较研究

目的:比较结构脂肪乳剂(STG)与物理混合的中/长链脂肪乳剂(MCT/LCT)在人体内的脂肪酸代谢情况.方法:40例健康志愿者随机分为STG组和MCT/LCT组,每组20例.分别于早晨6h内匀速输注20%力文脂肪乳剂和20%力保肪宁脂肪乳剂1.0 g/(kg·次).并于给药前和给药后2、4、6和24 h留取血标本测定血...     

Postprandial metabolism with 1,3-diacylglycerol oil versus equivalent intakes of long-chain and medium-chain triacylglycerol oils

ObjectiveWe assessed the ability of novel lipid structures including medium-chain triacylglycerols (MCTs) and 1,3-diacylglycerol (DG) oil to lower postprandial triacylglycerol (TG) elevation and increase hepatic fat oxidation when substituted for dietary TG, which may be useful in the prevention and treatment of obesity and other related metabolic conditions, such as dyslipidemias.MethodsThis double-blind, randomized, crossover trial evaluated the effects of an oral fat load containing DG or MCTs compared with equivalent intakes of long-chain triacylglycerols (LCTs) on the postprandial metabolic responses of insulin-resistant men and women (n = 36). Each subject consumed a single oral fat load on each test day. The fat loads were delivered in milkshakes that contained 30 g of one of the three test oils.ResultsThe postprandial TG incremental area under the curve after MCT was 73% lower, and that for DG was 22% lower, compared with the response after LCT oil. The incremental area under the curve values for chylomicron TG were reduced versus LCT by 89% and 28%, respectively, in the MCT and DG conditions. Compared with the LCT treatment, β-hydroxybutyrate concentration was increased after MCT oil, but not after DG.ConclusionThese results indicate that dietary DG decreased postprandial triglyceridemia compared with LCT, but to a lesser extent than MCT.     

Substrate oxidation and control of food intake in men after a fat-substitute meal compared with meals supplemented with an isoenergetic load of carbohydrate, long-chain triacylglycerols, or medium-chain triacylglycerols.

BACKGROUND: It has been suggested that hunger may be delayed and food intake reduced under metabolic conditions that spare carbohydrate oxidation. OBJECTIVE: Our objective was to examine the role of glucose metabolism in the control of food intake in men by using medium-chain triacylglycerols (MCTs) to spare carbohydrate oxidation. DESIGN: In 10 male volunteers, isolated and deprived of any time cues, we studied the effects of 4 lunches on hunger ratings, the duration of satiety, the amount of food ingested at dinner, energy expenditure, substrate oxidation, and plasma variables until the time of the dinner request. One lunch was a basic 2310-kJ meal containing 40 kJ fat substitute (Sub lunch). The 3 other lunches consisted of the same basic meal supplemented with either 1200 kJ long-chain triacylglycerols (LCT lunch), 1200 kJ MCTs (MCT lunch), or 900 kJ carbohydrate plus 300 kJ LCTs (Cho lunch). RESULTS: Energy expenditure was not significantly different after the different lunches, but carbohydrate oxidation was lower after the MCT and LCT lunches than after the Cho lunch. Fat oxidation was greater after the MCT and LCT lunches. The time of the dinner request was significantly delayed after the Cho lunch. Food intake at dinner was significantly lower after the MCT lunch than after the Sub and Cho lunches, but the dinner meal request was not delayed. CONCLUSION: Carbohydrate may have a greater role in the duration of satiety than does fat, but MCTs may play an active role in other aspects of the control of food intake, especially in satiation at the next meal.     

Inclusion of 10% fish oil in mixed medium-chain triacylglycerol-long-chain triacylglycerol emulsions increases plasma triacylglycerol clearance and induces rapid eicosapentaenoic acid (20:5n-3) incorporation into blood cell phospholipids

BACKGROUND: Lipolysis of a fish oil (FO) emulsion is much slower than that of a soybean [long-chain triacylglycerol (LCT)] emulsion; in contrast, emulsions containing medium-chain triacylglycerol (MCT) are efficiently hydrolyzed by lipoprotein lipase. OBJECTIVES: We questioned whether incorporating 10% FO in a mixed MCT-LCT emulsion would affect plasma triacylglycerol clearance and provide efficient delivery of n-3 polyunsaturated fatty acids to cells and tissues. DESIGN: This prospective crossover study was conducted in 8 normolipidemic subjects with the use of the hypertriglyceridemic clamp model and compared plasma triacylglycerol clearance of a lipid emulsion (5:4:1) made of 50% MCT, 40% LCT, and 10% FO (wt:wt:wt) to a control (5:5) preparation with 50% MCT and 50% LCT. Subjects were daily infused for 5 h, over 4 consecutive days. Fatty acyl pattern was daily measured in plasma phospholipids as well as in leukocyte and platelet phospholipids. RESULTS: Inclusion of 10% FO in mixed emulsion particles enhanced plasma clearance of infused triacylglycerols (18%; P < 0.0001). The faster elimination of the 5:4:1 emulsion appears related to an enhanced uptake of remnant particles rather than to faster intravascular lipolysis. Each infusion of 5:4:1 raised the eicosapentaenoic acid (C20:5n-3) concentration in blood cell phospholipids to reach a 7-fold enrichment in platelets and a >2-fold enrichment in leukocytes after 4 infusions. In contrast, the docosahexaenoic acid (C22:6n-3) concentration remained unchanged in blood cell phospholipids. CONCLUSIONS: Infusion of a mixed emulsion with MCTs, soy LCTs, and FO is associated with efficient plasma triacylglycerol clearance and results in rapid incorporation of C20:5n-3 but not C22:6n-3 in leukocyte and platelet phospholipids.