Medium-chain Triacylglycerols Oil Research Articles

Postprandial fatty acid metabolism with coconut oil in young females: a randomized, single-blind, crossover trial

BackgroundApproximately 84% of the fatty acids contained in coconut oil (CO) are saturated fatty acids (SFAs), and approximately 47% of the SFA are lauric acid with 12 carbon atoms. Lauric acid carbon chain length is intermediate between medium and long-chain fatty acids (LCFAs). We examined how CO acts on lipid-related substances in the blood to determine whether its properties were similar to medium-chain fatty acids (MCFAs) or LCFAs. MethodsThis is a randomized controlled, single-blind, crossover study. Fifteen females were enrolled, using 3 test meals containing 30 g each of 3 different oils: CO (CO-meal), medium-chain triacylglycerol oil (MCT-meal), and long-chain triacylglycerol oil (LCT-meal). Blood samples were collected at fasted baseline and every 2 h for 8 h after the intake of each test meal. ResultsRepeated measures ANOVA of the ketone bodies and triglyceride (TG) showed an interaction between time and the test meal (P < 0.01 and P < 0.001, respectively). In subsequent Tukey’s honestly significant difference (HSD) test of the ketone bodies, statistically significant differences were observed between the CO-meal and the LCT-meal (P < 0.05) 83.8 (95% CI, 14.7, 153.0) and between the MCT-meal and the LCT-meal (P < 0.05) 79.2 (95% CI, 10.0, 148.4). The incremental area under the curve (iAUC) and maximum increase in very low–density lipoprotein cholesterol (VLDL-C) and intermediate-density lipoprotein cholesterol (IDL-C) were the lowest for CO-meal intake. ConclusionsThe characteristics of lauric acid contained in CO, including the kinetics of β-oxidation and effects on blood TG, were very similar to those of MCFA. Moreover, regarding the iAUC and peak increment, VLDL-C and IDL-C were the lowest with the CO-meal. These results suggest that the intake of CO after fasting does not increase the TG, VLDL-C, and IDL-C, and may help prevent dyslipidemia.This trial was registered at UMIN (URL of registration: https://www.umin.ac.jp) as UMIN000019959.

Dietary Medium-Chain Fatty Acids Raise and (n-3) Polyunsaturated Fatty Acids Lower Hepatic Triacylglycerol Synthesis in Rats

The hypothesis tested was that dietary medium-chain or (n-3) polyunsaturated fatty acids, when compared with (n-6) polyunsaturated fatty acids, alter plasma triacylglycerol levels by affecting hepatic triacylglycerol synthesis as reflected by the activities of acetyl-CoA carboxylase, fatty acid synthase and diacylglycerol acyltransferase in liver. In two separate experiments rats were fed purified diets containing (n-6) polyunsaturated fatty acids in the form of corn oil and either (n-3) polyunsaturated fatty acids in the form of fish oil or medium-chain triacylglycerols (MCT). Consumption of MCT significantly raised plasma triacylglycerol concentrations, whereas fish oil feeding had a lowering effect compared with the corn oil-fed group. In individual rats, the hepatic triacylglycerol concentration was directly correlated with the plasma triacylglycerol concentration (r = 0.60, P < 0.001). The MCT oil diet vs. the corn oil diet markedly raised the activities of hepatic acetyl-CoA carboxylase, fatty acid synthase and diacylglycerol acyltransferase. In the rats fed fish oil, the activities of fatty acid synthase and diacylglycerol acyltransferase were significantly reduced, whereas the activity of acetyl-CoA carboxylase was not affected relative to activities in rats fed corn oil. The activities of the three enzymes were directly correlated with plasma triacylglycerol concentrations in individual rats (r = 0.60–0.75, P < 0.001). The type of fat in the diet probably affects the rate of hepatic triacylglycerol synthesis which is an important determinant of plasma triacylglycerol concentrations.

PHASE BEHAVIOUR OF HIGH, MEDIUM AND LOW MELTING FRACTIONS IN LAURIC FAT BLENDS FORMULATED BASED ON MELTING TRIACYLGLYCEROL GROUP

Lauric fat blends aimed for bakery shortening were prepared as a ternary mixture characterised by three distinct melting peaks on their differential scanning calorimeter (DSC) melting thermograms. Those melting peaks closely correlated to the high, medium, and low melting fractions (HMF, MMF and LMF) in the blends. In the simpler binary mixture, hard fats, (i.e. palm stearin and fully hydrogenated rapeseed oil) formed an ideal solubility in different liquid oils [i.e. medium chain triacylglycerol oil (MCI-oil) and high oleic sunflower oil (HOSO)]. However, slight deviations from ideality were observed when liquid oils were replaced by lauric oils (i.e. palm kernel oil and coconut oil). In the more complex ternary mixture, the I HMF formed an ideal solubility in both the MMF and LMF within the range of given formulas. In addition, the interaction of solid crystals in lauric fat blends was of monotectic behaviour as shown in the isosolid diagram. Nevertheless, the influence of solubility seemed to override that of solid interaction. Both the solubility curves and isosolid lines can provide valuable information about the interaction of HMF, MMF and LMF in lauric fat blends. Therefore, they are useful for improving the formulation of plastic fats.

Improved bioaccessibility of polymethoxyflavones loaded into high internal phase emulsions stabilized by biopolymeric complexes: A dynamic digestion study via TNO's gastrointestinal model

In this work, the bioaccessibility of polymethoxyflavones (PMFs) loaded in high internal phase emulsions (HIPE, ϕoil = 0.82) stabilized by whey protein isolate (WPI)-low methoxy pectin (LMP) complexes was evaluated using in vitro lipolysis and dynamic in vitro intestinal digestion studies. PMFs loaded HIPE was prepared by using aqueous dispersion of pre-formed biopolymeric complexes (WPI-LMP, 2:1 ratio) as the external phase and medium chain triglycerides oil (containing PMFs extracted from citrus peel) as the dispersed phase. The in vitro lipolysis study revealed that PMFs in HIPE became bioaccessible much higher than PMFs in medium chain triacylglycerols oil (MCT oil). In addition, by simulating the entire human gastrointestinal (GI) tract, the GI model TIM-1 demonstrated a 5- and 2-fold increase in the total bioaccessibility for two major PMFs encapsulated in HIPE, i.e. tangeretin (TAN) and nobiletin (NOB), respectively, as opposed to PMFs in MCT oil. Together these results from the digestion study showed that the incorporation of a high amount of PMFs into the viscoelastic matrix of HIPE could represent an innovative and effective way to design an oral delivery system. Such a system could be used to control and to improve the delivery of lipophilic bioactive compounds within the different compartments of the digestive tract, especially the human upper GI tract.

English

The rheological properties, oxidative stability, and water contents of the fried dough made from corn oil with medium-chain triacylglycerols (MCT), which is a mixture of MCT and corn oil at a volume ratio of 0% (0:100), 10% (10:90), 20% (20:80) and 30% (30:70) were studied. Flour dough was fried at 140°C for 6 min in fried dough and stored in a glass bottle at 50°C in the dark for 20 days. The water contents and the decreasing rate with storage time were lower in fried dough in corn oil containing MCT than in fried dough in 100% corn oil. The concentration of hydroperoxides in fried dough increased slightly for 8 days storage and increased rapidly thereafter. The concentration of hydroperoxides and the increasing rate with storage time were lower in fried dough in corn oil containing MCT than in fried dough in 100% corn oil. The hardness decreased slightly with 20 and 30% MCT oils for 20 days. In contrast, 0 and 10% MCT oils significantly increased the hardness. Adhesion of fried dough was slight with 20 and 30% MCT oil fried dough. From these results, it is a very high functional property to deep-fry dough that has been clarified with MCT. Key words: Medium-chain triacylglycerols (MCT), fried dough, corn oil, rheological properties, oxidative stability, hydroperoxide.

Medium chain triglycerides dose-dependently prevent liver pathology in a rat model of non-alcoholic fatty liver disease

Metabolic syndrome is often accompanied by development of hepatic steatosis and less frequently by non-alcoholic fatty liver disease (NAFLD) leading to non-alcoholic steatohepatitis (NASH). Replacement of corn oil with medium chain triacylglycerols (MCT) in the diets of alcohol-fed rats has been shown to protect against steatosis and alcoholic liver injury. The current study was designed to determine if a similar beneficial effect of MCT occurs in a rat model of NAFLD. Groups of male rats were isocalorically overfed diets containing 10%, 35% or 70% total energy as corn oil or a 70% fat diet in which corn oil was replaced with increasing concentrations of saturated fat (18:82, beef tallow:MCT oil) from 20% to 65% for 21 days using total enteral nutrition (TEN). As dietary content of corn oil increased, hepatic steatosis and serum alanine amino transferases were elevated (P < 0.05). This was accompanied by greater expression of cytochrome P450 enzyme CYP2E1 (P < 0.05) and higher concentrations of polyunsaturated 18:2 and 20:4 fatty acids (FA) in the hepatic lipid fractions (P < 0.05). Keeping the total dietary fat at 70%, but increasing the proportion of MCT-enriched saturated fat resulted in a dose-dependent reduction in steatosis and necrosis without affecting CYP2E1 induction. There was no incorporation of C8-C10 FAs into liver lipids, but increasing the ratio of MCT to corn oil: reduced liver lipid 18:2 and 20:4 concentrations; reduced membrane susceptibility to radical attack; stimulated FA β- and ω-oxidation as a result of activation of peroxisomal proliferator activated receptor (PPAR)α, and appeared to increase mitochondrial respiration through complex III. These data suggest that replacing unsaturated fats like corn oil with MCT oil in the diet could be utilized as a potential treatment for NAFLD.

Stability and bioavailability of lutein ester supplements from Tagetes flower prepared under food processing conditions

Tagetes spp. belongs to the Asteraceae family. It is recognized as a major source of lutein ester (lutein esterified with fatty acids such as lauric, myristic and palmitic acids), a natural colorant belonging to the xanthophylls or oxygenated carotenoids. Four species of Tagetes flower (Tagetes tenuifolia, Tagetes erecta, Tagetes patula, and Tagetes lucida) were used to extract lutein and lutein esters with three different methods. The results showed that T. erecta, type “orangeprinz”, is the richest source of lutein esters (14.4±0.234mg/g) in comparison to other Tagetes spp. No significant differences between extractions of lutein esters with medium-chain triacylglycerols (MCT) oil, orange oil or solvent (hexane/isopropanol) could be observed. MCT oil also improved stability of lutein esters at 100°C for 40min. Emulsification of MCT oil improved the stability of lutein ester extract against UV light at 365nm for 72h. Finally, an emulsion was prepared under food processing conditions, spray dried and its bioavailability investigated in a preliminary human intervention study. The results show a lower resorption, but further data suggest improvements in implementation of such supplements.

RETARDATION OF LIPID OXIDATION IN FISH OIL-ENRICHED FISH PÂTÉ- COMBINATION EFFECTS

The oxidative stability during storage of fish pâte made from cod and enriched with 5% oil was investigated. Pâtes were produced with neat fish oil, pre-emulsified fish oil, microencapsulated fish oil, inert medium chain triacylglycerol (MCT) oil or a fish/rapeseed oil mixture. Addition of fish oil decreased the oxidative stability. Fish pâte with microencapsulated fish oil or MCT oil did not oxidize, whereas oxidation was slower in fish pâte with pre-emulsified oil compared with fish pâte with neat oil. Packaging in vacuum did not decrease oxidation. Fish pâtes with emulsified oil stored at 2 or 10C were equally stable. Mixing fish oil with rapeseed oil before emulsification slightly increased the stability of the fish pâtes. Addition of antimicrobial agents, sodium benzoate and potassium sorbate increased oxidative stability. It is recommended to produce enriched fish pâte by adding pre-emulsified fish oil or microencapsulated fish oil and store at preferentially 2–10C. PRACTICAL APPLICATIONS The results from this study can directly be transferred to practical applications in the food industry. Thus, the study showed that fish oil-enriched fish pâte with an acceptable shelf life and good sensory properties can be produced if one or more of the following strategies are used: Use microencapsulated or pre-emulsified fish oil or pre-emulsified fish oil/rapeseed oil mixture as the fish oil delivery system and add antimicrobial agents to increase both microbial and oxidative stability. The fish pâte can be stored at temperatures up to 10C.

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

Objective We 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. Methods This 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. Results The 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. Conclusion These results indicate that dietary DG decreased postprandial triglyceridemia compared with LCT, but to a lesser extent than MCT.

Weight-loss diet that includes consumption of medium-chain triacylglycerol oil leads to a greater rate of weight and fat mass loss than does olive oil

Background: Clinical studies have shown that consumption of medium-chain triacylglycerols (MCTs) leads to greater energy expenditure than does consumption of long-chain triacylglycerols. Such studies suggest that MCT consumption may be useful for weight management.Objective: We aimed to determine whether consumption of MCT oil improves body weight and fat loss compared with olive oil when consumed as part of a weight-loss program.Design: Forty-nine overweight men and women, aged 19–50 y, consumed either 18–24 g/d of MCT oil or olive oil as part of a weight-loss program for 16 wk. Subjects received weekly group weight-loss counseling. Body weight and waist circumference were measured weekly. Adipose tissue distribution was assessed at baseline and at the endpoint by use of dual-energy X-ray absorptiometry and computed tomography.Results: Thirty-one subjects completed the study (body mass index: 29.8 ± 0.4, in kg/m2). MCT oil consumption resulted in lower endpoint body weight than did olive oil (−1.67 ± 0.67 kg, unadjusted P = 0.013). There was a trend toward greater loss of fat mass (P = 0.071) and trunk fat mass (P = 0.10) with MCT consumption than with olive oil. Endpoint trunk fat mass, total fat mass, and intraabdominal adipose tissue were all lower with MCT consumption than with olive oil consumption (all unadjusted P values < 0.05).Conclusions: Consumption of MCT oil as part of a weight-loss plan improves weight loss compared with olive oil and can thus be successfully included in a weight-loss diet. Small changes in the quality of fat intake can therefore be useful to enhance weight loss.

Oxidative stability, trans,trans-2,4-decadienals, and tocopherol contents during storage of dough fried in soybean oil with added medium-chain triacylglycerols (MCT)

The lipid oxidative stability, trans,trans-2,4-decadienals, and tocopherols content of dough fried in soybean oil with added medium-chain triacylglycerols (MCT) during storage in the dark were investigated. Flour dough was fried at 100 °C for 5 min in a mixture of MCT and soybean oil at a volume ratio of 0% (0:100), 20% (20:80), 30% (30:70), and 40% (40:60). Fried dough was stored in a glass bottle at 50 °C in the dark for 12 days. The peroxide value was slight with 30% and 40% MCT oils for 12 days. In contrast, 10% and 20% MCT oils significantly increased the peroxide value. The lowest concentration of trans,trans-2,4-decadienal in soybean oil with added MCT. Fried dough in soybean oil with added MCT during storage in the dark was significantly increased in 0% MCT and 10% MCT. In contrast, the lowest concentration of trans,trans-2,4-decadienal in soybean oil with added 30% MCT and 40% MCT. Total tocopherols in 0% MCT oil were degraded 79.5% in 12 days at 100 °C. In contrast, 40% MCT oil significantly decreased the rate of degradation. The ratio of unsaturated fatty acids to saturated fatty acids (U/S ratio) decreased and hydroperoxide content increased with storage time. U/S ratio and hydroperoxide and tocopherol contents were lower in dough fried in soybean oil with added MCT than in dough fried in 100% soybean oil, indicating decreased lipid oxidation.

Artificial rearing with docosahexaenoic acid and n-6 docosapentaenoic acid alters rat tissue fatty acid composition

Docosahexaenoic acid (DHA; 22:6n-3) and n-6 docosapentaenoic acid (DPAn-6; 22:5n-6) are components of enriched animal feed and oil derived from Schizochytrium species microalgae. A one generation, artificial rearing model from day 2 after birth onward (AR) and a dam-reared control group (DAM) were used to examine DPAn-6 feeding on the fatty acid composition of various rat tissues at 15 weeks of age. Four AR diets were based on an n-3 fatty acid-deficient, 18:2n-6-based artificial milk with 22:6n-3 and/or 22:5n-6 added: AR-LA, AR-DHA, AR-DPAn-6, and AR-DHA+DPAn-6. The 22:6n-3 levels for the DAM, AR-DHA, and AR-DHA+DPAn-6 groups tended to be similar and higher than in the AR-LA and AR-DPAn-6 groups. The levels of 22:5n-6 tended to be higher only in the absence of dietary 22:6n-3. Adipose levels of 22:5n-6 was the only exception, as 22:5n-6 was significantly higher in AR-DHA+DPAn-6 than was observed in either the DAM or the AR-DHA group. There were no differences in 20:4n-6 levels within the tissues examined. In conclusion, 22:5n-6 replaces 22:6n-3 in the absence of 22:6n-3 only and does not appear to compete with 22:6n-3 in the presence of dietary 22:6n-3, suggesting that oils containing 22:5n-6 and 22:6n-3 may be a good dietary source of 22:6n-3.

Slow Recrystallization of Tripalmitoylglycerol from MCT Oil Observed by 2H NMR

The crystallization and recrystallization of fats have a significant impact on the properties and quality of many food products. While crystallization has been the subject of a number of studies using pure triacylglycerols (TAG), recrystallization in similarly pure systems is rarely studied. In this work, perdeuterated tripalmitoylglycerol ( (2)H-PPP) was dissolved in medium chain triacylglycerol oil (MCT) to yield a saturated solution. The solution was heated to cause partial melting of the solid and dissolution of the molten fraction of (2)H-PPP in MCT and was then cooled to the original temperature to induce recrystallization from the supersaturated solution. (2)H NMR was used to monitor the disappearance of (2)H-PPP from the solution and showed that recrystallization occurred in two steps. The first step was rapid, taking place over a few minutes, and accounted for more than two-thirds of the total recrystallization. The second step was much slower, taking place over a remarkably long timescale of hours to days. It is proposed that dissolution occurs from all parts of the crystals, leaving an etched and pitted surface. The first step of crystallization is the infilling of these pits, while the second step is the continued growth on the smoothed crystal faces.

Safety evaluation of a medium- and long-chain triacylglycerol oil produced from medium-chain triacylglycerols and edible vegetable oil

To reduce the incorporation of dietary lipids into adipose tissue, modified fats and oils have been developed, such as medium-chain triacylglycerols (MCT). Typical dietary lipids from vegetable oils, termed long-chain triacylglycerols (LCT), are degraded by salivary, intestinal and pancreatic lipases into two fatty acids and a monoacyl glycerol; whereas, MCT are degraded by the same enzymes into three fatty acids and the simple glycerol backbone. Medium-chain fatty acids (MCFA) are readily absorbed from the small intestine directly into the bloodstream and transported to the liver for hepatic metabolism, while long-chain fatty acids (LCFA) are incorporated into chylomicrons and enter the lymphatic system. MCFA are readily broken down to carbon dioxide and two-carbon fragments, while LCFA are re-esterified to triacylglycerols and either metabolized for energy or stored in adipose tissue. Therefore, consumption of MCT decreases the incorporation of fatty acids into adipose tissue. However, MCT have technological disadvantages precluding their use in many food applications. A possible resolution is the manufacture and use of a triacylglycerol containing both LCT and MCT, termed medium- and long-chain triacylglycerol (MLCT). This manuscript describes studies performed for the safety evaluation of a MLCT oil enzymatically produced from MCT and edible vegetable oil (containing LCT), by a transesterification process. The approximate fatty acid composition of this MLCT consists of caprylic acid (9.7%), capric acid (3.3%), palmitic acid (3.8%), stearic acid (1.7%), oleic acid (51.2%), linoleic acid (18.4%), linolenic acid (9.0%), and other fatty acids (2.9%). The approximate percentages of long (L) and medium (M) fatty acids in the triacylglyerols are as follows: L, L, L (55.1%), L, L, M (35.2%), L, M, M (9.1%), and M, M, M (0.6%). The studies included: (1) acute study in rats (LD 50 > 5000 mg/kg); (2) 6 week repeat-dose safety study via dietary administration to rats (NOAEL of 3500 mg/kg/day), (3) in vitro genotoxicity studies using Salmonella typhimurium and Escherichia coli (negative at 5000 mg/plate), and (4) a four-week, placebo-controlled, double blind, human clinical trial utilizing 20 test subjects (no effects at 42 g MLCT/day). These data are corroborated by other studies published in the peer-reviewed literature on analogous MLCTs.

Effect of dietary medium chain triacylglycerols on plasma triacylglycerol levels in horses

The hypothesis tested was that the feeding of medium chain triacylglycerols (MCT) to horses would raise the level of plasma triacylglycerols by increasing the availability of glucose as lipogenic substrate, implying that the MCT effect would be greater with glucose in the diet instead of cellulose. A Latin square experiment was carried out with 4 horses and 4 dietary treatments. The experimental periods lasted 21 d. Blood samples were taken 16 h after feeding. The diets consisted of hay and experimental concentrates, differing in fat source (MCT or soybean oil) and carbohydrate source (corn starch plus glucose or cellulose). The dietary variables, MCT or soybean oil, provided on average 27% of total dietary net energy, while glucose plus cornstarch or cellulose provided 33%. The feeding of MCT versus soybean oil raised the level of plasma triacylglycerols significantly from 196.7 ± 30.2 to 427.3 ± 85.7 mmol/1 and that of VLDL cholesterol from 0.028 ± 0.01 to 0.069 ± 0.01 mmol/ml. As based on analysis of variance, for the four experimental diets there was no significant effect of carbohydrate source and no fat‐carbohydrate interaction. Thus, the hypothesis was rejected. When the diets contained soybean oil, cellulose versus starch plus glucose produced significantly greater increase plasma triacylglycerols. This carbohydrate effect was not seen when horses were fed the MCT diets. The experimental concentrates did not differently influence the concentrations of plasma glucose, total serum cholesterol, phospholipids, insulin, free fatty acids and the activity of post‐heparin lipoprotein lipase. We suggest that the MCT‐induced increase in plasma triacylglycerols is related to an increase in hepatic VLDL secretion, with the extra substrate for increased synthesis of triacylglycerols being the acetyl‐CoA derived from the hepatic oxidation of medium chain fatty acids.

The effect of medium-chain triacylglycerols on the blood lipid profile of male endurance runners

Medium-chain triacylglycerol (MCT) oil is currently marketed for athletes as an ergogenic aid for optimal performance. Research assessing the blood lipid response of humans to MCT consumption is very limited and inconclusive. In this randomized cross-over study, male endurance runners (aged 30.5 ± 5.5 years) were instructed to consume a low-fat diet (approximately 15% of energy) and consume either supplemental MCT oil (30 g twice each day) or long-chain triacylglycerol (LCT) oil (28 g corn oil twice each day) for 14 days. Each dietary trial was separated by at least 3 weeks. At the end of each trial, fasting blood samples were collected and analyzed for serum concentrations of total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), and triacylglycerol (TG). Concentrations of TC (3.83 ± 0.12 vs. 3.41 ± 0.15 mmol/L, P = 0.004), LDL-C (1.76 ± 0.12 vs. 1.51 ± 0.14 mmol/L, P = 0.033), and TG (1.26 ± 0.14 vs. 0.98 ± 0.12 mmol/L, P = 0.006) were higher following the MCT trial than following the LCT trial, respectively. HDL-C concentration did not differ significantly between trials (MCT 1.48 ± 0.05 mmol/L vs. LCT 1.45 ± 0.04 mmol/L, P = 0.465). Although blood lipids remained within desirable ranges established by the National Cholesterol Education Program, these results suggest that consumption of MCT oil for 2 weeks negatively alters the blood lipid profile of athletes. Future studies should determine the effects of longer periods of MCT supplementation on serum lipids of exercisers and other groups of individuals. With little data suggesting that MCT are ergogenic, the adverse effects of MCT on blood lipid concentrations may outweigh any proposed benefits for athletes.

Dietary medium-chain triacylglycerol prevents the postprandial rise of plasma triacylglycerols but induces hypercholesterolemia in primary hypertriglyceridemic subjects

Previous studies showed divergent results concerning the influence of medium-chain triacylglycerol (MCT) on lipoprotein metabolism. The objective of this study was to compare the effects of MCT and corn oil on plasma lipids in primary hypertriglyceridemic patients. Ten subjects ate different proportions of corn oil and MCT for 12 wk. The subjects first ate a low-fat diet for 2 wk and during the next 4 wk, corn oil was added as the sole source of fat. Thereafter, for 2-wk periods, the subjects were sequentially fed corn oil and MCT mixed in the following proportions: 3:1, 1:1, and 0:1. Fasting plasma total cholesterol, triacylglycerol, and HDL-cholesterol concentrations were measured at the end of each period. At the end of the 100%-corn oil and of the 100%-MCT periods, subjects were fed a test meal containing the respective oil (40 g fat/m(2) body surface area) and total cholesterol and triacylglycerols were measured at 2-h intervals over 8 h; fasting lipoprotein composition was also measured. Compared with corn oil, MCT was associated with a higher mean (+/-SD) fasting total cholesterol concentration (6.39 +/- 1.14 compared with 5.51 +/- 0.98 mmol/L, respectively; P < 0. 05); non-HDL-cholesterol concentrations were also higher with MCT (5. 36 +/- 1.11 mmol/L) than with corn oil (4.51 +/- 0.92 mmol/L; P < 0. 005). In response to the liquid test meal, plasma total cholesterol did not change with either diet but triacylglycerols increased with the 100%-corn oil diet. MCT prevents the risk of pancreatitis due to postprandial hypertriglyceridemia but has the inconvenience of raising total cholesterol concentrations in primary hypertriglyceridemic subjects.

Suppression of fatty acids synthesis in brown adipose tissue of mice fed diets rich dm long chain fatty acids

The influence of dietary lipid on fatty acid synthesis in brown adipose tissue has been investigated by feeding different high-fat diets to cold-acclimated mice for a period of 2 weeks. Fatty acid synthesis was measured in vivo with 3H 2O, and the fats used in the study were maize oil, beef tallow and medium chain triacylglycerol oil. In the mice fed the maize oil and the beef tallow diets fatty acid synthesis was inhibited in all tissues examined — inter-scapular brown adipose tissue, epididymal white adipose tissue, the liver and the carcass. Synthesis was more inhibited, however, in brown adipose tissue than in other tissues, and the inhibition was greater on the maize oil diet than on the beef tallow. The medium chain triacylglycerol oil had no inhibitory effect on fatty acid synthesis in any tissue, and hepatic synthesis was even elevated on this diet. It is concluded that fatty acid synthesis in brown adipose tissue, as in other lipogenic tissues, is subject to strong suppression by dietary long chain fatty acids, and particularly by linoleic acid.